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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
quant-ph/0702088 | Alastair Kay | Alastair Kay | The Impossibility of Quantum State Mirroring on Square Lattices | 4 pages, 3 figures | null | null | null | quant-ph | null | We discuss the possibility of engineering a Hamiltonian that can perfectly
mirror a state of many excitations stored on a square lattice. In comparison to
the well-studied case of a chain, there is potential for a speed-up of
information transfer. However, we prove that in a large class of cases, perfect
state mirroring on a square lattice is impossible.
| [
{
"version": "v1",
"created": "Fri, 9 Feb 2007 14:42:08 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Kay",
"Alastair",
""
]
] |
quant-ph/0702089 | Paulo Maia Neto | Robson B. Rodrigues, Paulo A. Maia Neto, Astrid Lambrecht, Serge
Reynaud | Reply to ``Comment on ``Lateral Casimir Force beyond the Proximity Force
Approximation'' '' | 1 page | Phys. Rev. Letters 98, 068902 (2007) | 10.1103/PhysRevLett.98.068902 | null | quant-ph | null | We reply to the comment arXiv:quant-ph/0702060 on our letter
arXiv:quant-ph/0603120 [Phys. Rev. Lett. 96, 100402 (2006)]
| [
{
"version": "v1",
"created": "Fri, 9 Feb 2007 13:29:40 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Rodrigues",
"Robson B.",
""
],
[
"Neto",
"Paulo A. Maia",
""
],
[
"Lambrecht",
"Astrid",
""
],
[
"Reynaud",
"Serge",
""
]
] |
quant-ph/0702090 | Leonid A. Krivitsky | G. Brida, M.V. Chekhova, M. Genovese, L.A. Krivitsky | Entanglement generation via phase-matched processes: different Bell
states within the linewidth | submitted for publication | Optics Express Vol.15, No.16, 10182-10188 (2007) | null | null | quant-ph | null | It is shown, theoretically and experimentally, that at any type-II
spontaneous parametric down-conversion (SPDC) phase matching, the
decoherence-free singlet Bell state is always present within the natural
bandwidth and can be filtered out by a proper spectral selection. Instead of
the frequency selection, one can perform time selection of the two-photon time
amplitude at the output of a dispersive fibre. Applications to quantum
communication are outlined.
| [
{
"version": "v1",
"created": "Fri, 9 Feb 2007 13:40:57 GMT"
}
] | 2007-10-01T00:00:00 | [
[
"Brida",
"G.",
""
],
[
"Chekhova",
"M. V.",
""
],
[
"Genovese",
"M.",
""
],
[
"Krivitsky",
"L. A.",
""
]
] |
quant-ph/0702091 | Wojciech Wasilewski | Konrad Banaszek and Wojciech Wasilewski | Linear-optics manipulations of photon-loss codes | Proceedings of NATO Advanced Research Workshop "Quantum Communication
and Security" | null | null | null | quant-ph | null | We discuss codes for protecting logical qubits carried by optical fields from
the effects of amplitude damping, i.e. linear photon loss. We demonstrate that
the correctability condition for one-photon loss imposes limitations on the
range of manipulations than can be implemented with passive linear-optics
networks.
| [
{
"version": "v1",
"created": "Fri, 9 Feb 2007 14:18:49 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Banaszek",
"Konrad",
""
],
[
"Wasilewski",
"Wojciech",
""
]
] |
quant-ph/0702092 | Alastair Kay | Alastair Kay | The Topological Properties of Fault-Tolerant Circuits | This paper has been withdrawn because there are errors in it. I have
always believed them to be fixable, but have never had the time to go back
and do so | null | null | null | quant-ph | null | The design of time-independent local Hamiltonians that realise quantum
algorithms is derived from the study of perfect state transfer. The novel
features of this evolution are the perfect realisation of the computation, and
the ability to implement operations in parallel rather than sequentially. This
is applied to a quantum circuit for concatenated error correcting codes, and
the properties of the eigenstates are compared to those of topological
memories. An erroneous implementation of the algorithm (one where a single
error could lead to a fault in the output) is found not to be topological,
whereas a true fault-tolerant algorithm possesses self-correcting properties,
suggesting the existence of a unifying structure for fault-tolerant memories.
| [
{
"version": "v1",
"created": "Fri, 9 Feb 2007 14:31:34 GMT"
},
{
"version": "v2",
"created": "Tue, 24 Apr 2007 09:08:51 GMT"
},
{
"version": "v3",
"created": "Mon, 12 Nov 2007 14:15:40 GMT"
},
{
"version": "v4",
"created": "Fri, 25 Nov 2016 10:17:07 GMT"
}
] | 2016-11-28T00:00:00 | [
[
"Kay",
"Alastair",
""
]
] |
quant-ph/0702093 | Horace P. Yuen | Ranjith Nair & Horace P. Yuen | On the Security of the Y-00 (AlphaEta) Direct Encryption Protocol | Conference Proceedings article of a contribution to QCMC 2006; claims
made more precise and some other minor changes | null | null | null | quant-ph | null | We review the current status of the AlphaEta direct encryption protocol.
After describing AlphaEta, we summarize the main security claims made on it. We
then describe recent attacks developed against it in the literature, and
suggest security enhancements and future research directions based on our
results.
| [
{
"version": "v1",
"created": "Fri, 9 Feb 2007 22:22:55 GMT"
},
{
"version": "v2",
"created": "Thu, 1 Mar 2007 20:44:51 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Nair",
"Ranjith",
""
],
[
"Yuen",
"Horace P.",
""
]
] |
quant-ph/0702094 | Owen Maroney | O. J. E. Maroney | Generalising Landauer's Principle | 29 pages, 4 figures. v4 Major changes to thermodynamic reversibility
discussion | PHYSICAL REVIEW E 79, 031105 (2009) | 10.1103/PhysRevE.79.031105 | pi-foundqt-41 | quant-ph cond-mat.stat-mech | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In a recent paper [Mar05] it is argued that to properly understand the
thermodynamics of Landauer's Principle it is necessary extend the concept of
logical operations to include indeterministic operations. Here we examine the
thermodynamics of such operations in more detail, extending the work of
Landuaer[Lan61] to include indeterministic operations and to include logical
states with variable entropies, temperatures and mean energies. We derive the
most general statement of Landauer's Principle and prove it's universality,
extending considerably the validity of previous proofs. This confirms
conjectures made in [Mar05b], in particular that all logical operations may, in
principle, be performed in a thermodynamically reversible fashion. We
demonstrate a physical process that can perform any computation without work
requirements or heat exchange with the environment. Many widespread statements
of Landauer's Principle are shown to be only special cases of our generalised
principle.
| [
{
"version": "v1",
"created": "Fri, 9 Feb 2007 22:51:00 GMT"
},
{
"version": "v2",
"created": "Wed, 15 Aug 2007 21:31:05 GMT"
},
{
"version": "v3",
"created": "Mon, 30 Nov 2009 07:14:00 GMT"
}
] | 2009-11-30T00:00:00 | [
[
"Maroney",
"O. J. E.",
""
]
] |
quant-ph/0702095 | Almut Beige | Jeremy Metz and Almut Beige | Macroscopic quantum jumps and entangled state preparation | 14 pages, 12 figures, proof of the robustness of the state
preparation against parameter fluctuations added, figure replaced | Phys. Rev. A 76, 022331 (2007). | 10.1103/PhysRevA.76.022331 | null | quant-ph | null | Recently we predicted a random blinking, i.e. macroscopic quantum jumps, in
the fluorescence of a laser-driven atom-cavity system [Metz et al., Phys. Rev.
Lett. 97, 040503 (2006)]. Here we analyse the dynamics underlying this effect
in detail and show its robustness against parameter fluctuations. Whenever the
fluorescence of the system stops, a macroscopic dark period occurs and the
atoms are shelved in a maximally entangled ground state. The described setup
can therefore be used for the controlled generation of entanglement. Finite
photon detector efficiencies do not affect the success rate of the state
preparation, which is triggered upon the observation of a macroscopic
fluorescence signal. High fidelities can be achieved even in the vicinity of
the bad cavity limit due to the inherent role of dissipation in the jump
process.
| [
{
"version": "v1",
"created": "Sat, 10 Feb 2007 00:02:07 GMT"
},
{
"version": "v2",
"created": "Mon, 4 Jun 2007 18:32:22 GMT"
},
{
"version": "v3",
"created": "Tue, 5 Jun 2007 08:23:26 GMT"
},
{
"version": "v4",
"created": "Thu, 28 Jun 2007 15:56:40 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Metz",
"Jeremy",
""
],
[
"Beige",
"Almut",
""
]
] |
quant-ph/0702096 | Alexandre Shkorbatov | A.G. Shkorbatov | The method of partial wave functions and the structure of time interval
between the subsequent quantum transitions | 45 pages, 3 figures | null | null | null | quant-ph | null | We present the formulation of non relativistic quantum mechanics in the
extended space (u,x,t) where x and t are coordinates of particles and time, and
u - an additional real parameter that corresponds to generalized virial - an
integral over path on potential energy of the particle. If the u value is
defined, the state of a particle is described by the partial wave function
F(u,x,t) (PWF). The wave function is obtained from F(u,x,t) by special integral
transform. The "drift" wave equation (DWE) for F(u,x,t) is introduced. The
integral invariants of F(u,x,t) evolution are obtained. The sets of orthonormal
solutions for stationary DWE are obtained; the moments of distribution of are
calculated. The process of "aging" of PWF is described. Effective time interval
necessary for the creation of the state is calculated within the limits of PWF
formalism. The structure of the time interval between the processes of
consequent quantum transition is investigated. The theoretical basis for the
describing counterfactual situations in quantum mechanics is examined.
| [
{
"version": "v1",
"created": "Sat, 10 Feb 2007 06:25:16 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Shkorbatov",
"A. G.",
""
]
] |
quant-ph/0702097 | Keiji Matsumoto | David Fattal, Keiji Matsumoto | Strong Super-additivity of the entanglement of formation for pure
stabilizer states | null | null | null | null | quant-ph | null | We prove the strong super-additivity of the entanglement of formation for
stabilizer pure states, and the set of mixed states which minimize their
average entropy of entanglement as a mixture of stabilizer pure states sharing
the same stabilizer group up to phases. The implications of the result on the
additivity of the Holevo capacity of a quantum channel transmitting stabilizer
states with Pauli noise is discussed.
| [
{
"version": "v1",
"created": "Sat, 10 Feb 2007 09:08:36 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Fattal",
"David",
""
],
[
"Matsumoto",
"Keiji",
""
]
] |
quant-ph/0702098 | Viacheslav Belavkin | V.P.Belavkin and X.Dai | Additivity of Entangled Channel Capacity for Quantum Input States | 17 pages. See the related papers at
http://www.maths.nott.ac.uk/personal/vpb/research/ent_com.html | null | 10.1142/9789812832962_0017 | null | quant-ph | null | An elementary introduction into algebraic approach to unified quantum
information theory and operational approach to quantum entanglement as
generalized encoding is given. After introducing compound quantum state and two
types of informational divergences, namely, Araki-Umegaki (a-type) and of
Belavkin-Staszewski (b-type) quantum relative entropic information, this paper
treats two types of quantum mutual information via entanglement and defines two
types of corresponding quantum channel capacities as the supremum via the
generalized encodings. It proves the additivity property of quantum channel
capacities via entanglement, which extends the earlier results of V. P.
Belavkin to products of arbitrary quantum channels for quantum relative entropy
of any type.
| [
{
"version": "v1",
"created": "Sat, 10 Feb 2007 10:50:53 GMT"
}
] | 2017-08-23T00:00:00 | [
[
"Belavkin",
"V. P.",
""
],
[
"Dai",
"X.",
""
]
] |
quant-ph/0702099 | Afshin Shafiee Dr. | Mohammad Bahrami and Afshin Shafiee | On The Significance of Which-Way Expositions: Propounding a New
Possibility | 21 pages, 4 figures, this is the second version which includes many
amendments in exploring the issue | null | null | null | quant-ph | null | In this article, we survey some controversial problems concerning the idea of
erasing Which Way information proposed in recent years. A statistical
examination of these proposals suggests that whenever the Bayesian rule is
taken into account for two relevant events in two successive times, the
probabilistic description of them is unavoidably time-symmetric. Consequently,
it seems that they cannot fulfill the implications of a so-called
delayed-choice experiment. As a possible alternative, however, we suggest a new
experimental arrangement in which one can change the whole state of a given
system at a proper time (without measurement) to accomplish an actual
delayed-choice experiment with a time-asymmetric attribute. The peculiar
features of this experiment are then discussed.
| [
{
"version": "v1",
"created": "Sat, 10 Feb 2007 11:39:50 GMT"
},
{
"version": "v2",
"created": "Mon, 20 Aug 2007 12:11:56 GMT"
}
] | 2007-08-20T00:00:00 | [
[
"Bahrami",
"Mohammad",
""
],
[
"Shafiee",
"Afshin",
""
]
] |
quant-ph/0702100 | Aurelian Isar | A. Isar and W. Scheid | Uncertainty functions of the open quantum harmonic oscillator in the
Lindblad theory | 23 pages, 8 figures | Phys. Rev. A 66, 042117 (2002) | 10.1103/PhysRevA.66.042117 | null | quant-ph | null | In the framework of the Lindblad theory for open quantum systems, we derive
closed analytical expressions of the Heisenberg and Schr\"odinger generalized
uncertainty functions for a particle moving in a harmonic oscillator potential.
The particle is initially in an arbitrary correlated coherent state, and
interacts with an environment at finite temperature. We describe how the
quantum and thermal fluctuations contribute to the uncertainties in the
canonical variables of the system and analyze the relative importance of these
fluctuations in the evolution of the system. We show that upon contact with the
bath the system evolves from a quantum-dominated to a thermal-dominated state
in a time that is of the same order as the decoherence time calculated in other
models in the context of transitions from quantum to classical physics.
| [
{
"version": "v1",
"created": "Sat, 10 Feb 2007 20:13:34 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Isar",
"A.",
""
],
[
"Scheid",
"W.",
""
]
] |
quant-ph/0702101 | S. Javad Akhtarshenas | S. J. Akhtarshenas and M. Farsi | Negativity as Entanglement Degree of the Jaynes-Cummings Model | 10 pages, 5 figures | Physica Scripta, 75 (2007) 608-614 | null | null | quant-ph | null | In this paper, by using the notion of negativity, we study the degree of
entanglement of a two-level atom interacting with a quantized radiation field,
described by the Jaynes-Cummings model (JCM). We suppose that initially the
field is in a pure state and the atom is in a general mixed state. In this case
the negativity fully captures the entanglement of the JCM. We investigate the
case for that the initial state of the field is a coherent state. The
influences of the detuning on the degree of entanglement is also examined.
| [
{
"version": "v1",
"created": "Sun, 11 Feb 2007 05:48:13 GMT"
},
{
"version": "v2",
"created": "Fri, 9 Mar 2007 16:59:50 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Akhtarshenas",
"S. J.",
""
],
[
"Farsi",
"M.",
""
]
] |
quant-ph/0702102 | Michal Horodecki | R. Alicki, M. Fannes and M. Horodecki | A statistical mechanics view on Kitaev's proposal for quantum memories | null | J. Phys. A: Math. Theor. 40 (2007) 6451-6467. | 10.1088/1751-8113/40/24/012 | null | quant-ph | null | We compute rigorously the ground and equilibrium states for Kitaev's model in
2D, both the finite and infinite version, using an analogy with the 1D Ising
ferromagnet. Next, we investigate the structure of the reduced dynamics in the
presence of thermal baths in the Markovian regime. Special attention is paid to
the dynamics of the topological freedoms which have been proposed for storing
quantum information.
| [
{
"version": "v1",
"created": "Sun, 11 Feb 2007 11:20:51 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Alicki",
"R.",
""
],
[
"Fannes",
"M.",
""
],
[
"Horodecki",
"M.",
""
]
] |
quant-ph/0702103 | Xiaoguang Wang | Zhihao Ma and Xiaoguang Wang | Matrix realignment and partial transpose approach to entangling power of
quantum evolutions | Four pages and no figures | Phys. Rev. A 75, 014304 (2007) | 10.1103/PhysRevA.75.014304 | null | quant-ph | null | Based on the matrix realignment and partial transpose, we develop an approach
to entangling power and operator entanglement of quantum unitary operators. We
demonstrate efficiency of the approach by studying several unitary operators on
qudits, and indicate that these two matrix rearrangements are not only powerful
for studying separability problem of quantum states, but also useful in
studying entangling capabilities of quantum operators.
| [
{
"version": "v1",
"created": "Mon, 12 Feb 2007 01:22:51 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Ma",
"Zhihao",
""
],
[
"Wang",
"Xiaoguang",
""
]
] |
quant-ph/0702104 | Gui Lu Long | W. Y. Huo and G. L. Long | Scalable quantum computer using superconducting charge qubits | 4 pages and 2 figures. References added, and W-state generation added | null | null | null | quant-ph | null | We present a scalable scheme for superconducting charge qubits with the
assistance of one-dimensional superconducting transmission line resonator
(STLR) playing the role of data bus. The coupling between qubit and data bus
may be turned on and off by just controlling the gate voltage and externally
applied flux of superconducting charge qubit. In our proposal, the entanglement
between arbitrary two qubits and $W$ states of three qubits can be generated
quickly and easily.
| [
{
"version": "v1",
"created": "Mon, 12 Feb 2007 02:49:14 GMT"
},
{
"version": "v2",
"created": "Fri, 15 Jun 2007 14:19:57 GMT"
}
] | 2011-11-09T00:00:00 | [
[
"Huo",
"W. Y.",
""
],
[
"Long",
"G. L.",
""
]
] |
quant-ph/0702105 | Ju Gao Dr | Ju Gao, Fang Shen | Ponderomotive tunneling in electron-laser interactions | 4 figures | null | null | null | quant-ph | null | It is known that the ponderomotive potential from the laser electron
interaction behaves like a static potential that scatters off electrons. We
have investigated the process of the electron tunneling the ponderomotive
potential by using the nonperturbative quantum electrodynamic approach with a
modified Gaussian quantized laser field. The results show that the
ponderomotive tunneling is significantly larger than the tunneling of a static
potential of the same profile. The tunneled electron is discrete in energy
spectrum and spatial diffraction as the result of multiphoton processes. A
resonant tunneling occurs when the ponderomotive energy equals the multiple
integer of the laser photon energy.
| [
{
"version": "v1",
"created": "Mon, 12 Feb 2007 03:32:05 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gao",
"Ju",
""
],
[
"Shen",
"Fang",
""
]
] |
quant-ph/0702106 | M.K. Balasubramanya | M.K.Balasubramanya | Frequencies and energy levels of the weakly relativistic harmonic
oscillator from the action variable | null | null | null | null | quant-ph | null | The frequency of a classical periodic system and the energy levels of the
corresponding quantum system can both be obtained using action variables. We
demonstrate the construction of two forms of the action variable for a one
dimensional harmonic oscillator in classical, relativistic and quantum regimes.
The relativistic effects are considered as perturbative, within the context of
a non-relativistic quantum formalism. The transition of the relativistic
quantum system to both classical relativistic and classical non-relativistic
regimes is illustrated in a unified framework. Formulas for the frequency of a
classical relativistic oscillator and the energy eigenvalues of the
corresponding quantum oscillator for the weak relativistic case are derived.
Also studied are the non-relativistic and classical limits of these formulas
which provide valuable insights on the parallels between relativistic and
non-relativistic systems on the one hand and between classical and quantum
systems on the other.
| [
{
"version": "v1",
"created": "Mon, 12 Feb 2007 06:41:43 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Balasubramanya",
"M. K.",
""
]
] |
quant-ph/0702107 | Jason Twamley | J. Twamley and G. J. Milburn | The Quantum Mellin transform | 23 pages, 6 Figures | New J Phys 8 328 (2006) | 10.1088/1367-2630/8/12/328 | null | quant-ph | null | We uncover a new type of unitary operation for quantum mechanics on the
half-line which yields a transformation to ``Hyperbolic phase space''. We show
that this new unitary change of basis from the position x on the half line to
the Hyperbolic momentum $p_\eta$, transforms the wavefunction via a Mellin
transform on to the critial line $s=1/2-ip_\eta$. We utilise this new transform
to find quantum wavefunctions whose Hyperbolic momentum representation
approximate a class of higher transcendental functions, and in particular,
approximate the Riemann Zeta function. We finally give possible physical
realisations to perform an indirect measurement of the Hyperbolic momentum of a
quantum system on the half-line.
| [
{
"version": "v1",
"created": "Mon, 12 Feb 2007 11:42:37 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Twamley",
"J.",
""
],
[
"Milburn",
"G. J.",
""
]
] |
quant-ph/0702108 | Sintayehu Tesfa Woldemariam Mr | Sintayehu Tesfa | Output radiation from a degenerate parametric oscillator | 7 pages, 5 figures | null | null | null | quant-ph | null | We study the squeezing as well as the statistical properties of the output
radiation from a degenerate parametric oscillator coupled to a squeezed vacuum
reservoir employing the stochastic differential equations associated with the
normal ordering. It is found that the degree of squeezing of the output
radiation is less than the corresponding cavity radiation. However, for output
radiation the correlation of the quadrature operators evaluated at different
times also exhibits squeezing, which is the reason for quenching of the overall
noise in one of the quadrature components of the squeezing spectrum even when
the oscillator is coupled to a vacuum reservoir. Moreover, coupling the
oscillator to the squeezed vacuum reservoir enhances the squeezing
exponentially and it also increases the mean photon number.
| [
{
"version": "v1",
"created": "Mon, 12 Feb 2007 12:16:58 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Tesfa",
"Sintayehu",
""
]
] |
quant-ph/0702109 | Alexei Taichenachev | A.V. Taichenachev and V.I. Yudin | Vector Cooper Pairs and Coherent-Population-Trapping-like States in
Ensemble of Interacting Fermions | revtex, 12 pages, 2 figures | null | 10.1140/epjd/e2008-00115-2 | null | quant-ph cond-mat.str-el cond-mat.supr-con physics.atom-ph | null | Using the standard Hamiltonian of the BCS theory, we show that in an ensemble
of interacting fermions with the spin 1/2 there exist coherent states $|NC>$,
which nullify the Hamiltonian of the interparticle interaction (scattering).
These states have an analogy with the well-known in quantum optics the coherent
population trapping (CPT) effect. The structure of these CPT-like states
corresponds to Cooper pairs with the total spin $S$=1. The found states have a
huge degree of degeneracy and carry a macroscopic magnetic moment, that allows
us to construct a new model of the magnetism connected with the delocalized
electrons in metals (conductors). A principal possibility to apply the obtained
results to the superfluid $^3$He is also demonstrated.
| [
{
"version": "v1",
"created": "Mon, 12 Feb 2007 14:36:31 GMT"
},
{
"version": "v2",
"created": "Wed, 14 Feb 2007 14:21:19 GMT"
},
{
"version": "v3",
"created": "Mon, 18 Feb 2008 11:14:03 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Taichenachev",
"A. V.",
""
],
[
"Yudin",
"V. I.",
""
]
] |
quant-ph/0702110 | Charbel Tannous | C. Tannous, K. Fakhreddine and J. Langlois | The Canonical Function Method and its applications in Quantum Physics | 30 pages, 12 figures- To submit to Reviews of Modern Physics | null | 10.1016/j.physrep.2008.07.001 | null | quant-ph | null | The Canonical Function Method (CFM) is a powerful method that solves the
radial Schr\"{o}dinger equation for the eigenvalues directly without having to
evaluate the eigenfunctions. It is applied to various quantum mechanical
problems in Atomic and Molecular physics with presence of regular or singular
potentials. It has also been developed to handle single and multiple channel
scattering problems where the phaseshift is required for the evaluation of the
scattering cross-section. Its controllable accuracy makes it a valuable tool
for the evaluation of vibrational levels of cold molecules, a sensitive test of
Bohr correspondance principle and a powerful method to tackle local and
non-local spin dependent problems.
| [
{
"version": "v1",
"created": "Mon, 12 Feb 2007 14:38:01 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Tannous",
"C.",
""
],
[
"Fakhreddine",
"K.",
""
],
[
"Langlois",
"J.",
""
]
] |
quant-ph/0702111 | R. de la Madrid | R. de la Madrid, J.M. Isidro | A selfadjoint variant of the time operator | 7 pages | Adv.Stud.Theor.Phys.2:281-289,2008 | null | null | quant-ph gr-qc hep-th | null | We study the selfadjoint time operator recently constructed by one of the
authors. We will show that this time operator must be interpreted as a
``selfadjoint variant'' of the time operator.
| [
{
"version": "v1",
"created": "Mon, 12 Feb 2007 16:45:12 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"de la Madrid",
"R.",
""
],
[
"Isidro",
"J. M.",
""
]
] |
quant-ph/0702112 | Marcello Salis | P. Brovetto, V. Maxia, M. Salis | Are elementary particles point-like objects? | null | null | null | null | quant-ph | null | Simple arguments based on uncertainty principle and Dirac's equation are
examined which show that electron behaves either as a point-like charge or as
an extended distribution according as high- or low-energy experiments are
considered.
| [
{
"version": "v1",
"created": "Mon, 12 Feb 2007 17:50:16 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Brovetto",
"P.",
""
],
[
"Maxia",
"V.",
""
],
[
"Salis",
"M.",
""
]
] |
quant-ph/0702113 | Eugenio Roldan | F.V. Garcia-Ferrer, I. Perez-Arjona, G.J. de Valcarcel, and E. Roldan | Quadrature and polarization squeezing in a dispersive optical
bistability model | 10 text pages + 12 figures | Physical Review A 75, 063823 (2007) | 10.1103/PhysRevA.75.063823 | null | quant-ph | null | We theoretically study quadrature and polarization squeezing in dispersive
optical bistability through a vectorial Kerr cavity model describing a
nonlinear cavity filled with an isotropic chi(3) medium in which self-phase and
cross-phase modulation, as well as four--wave mixing, occur. We derive
expressions for the quantum fluctuations of the output field quadratures as a
function of which we express the spectrum of fluctuations of the output field
Stokes parameters. We pay particular attention to study how the bifurcations
affecting the non-null linearly polarized output mode squeezes the orthogonally
polarized vacuum mode, and show how this produces polarization squeezing.
| [
{
"version": "v1",
"created": "Mon, 12 Feb 2007 18:36:19 GMT"
}
] | 2007-07-31T00:00:00 | [
[
"Garcia-Ferrer",
"F. V.",
""
],
[
"Perez-Arjona",
"I.",
""
],
[
"de Valcarcel",
"G. J.",
""
],
[
"Roldan",
"E.",
""
]
] |
quant-ph/0702114 | Fred Thaheld H | Fred H. Thaheld | Nature as the observer: A simplified approach to the measurement problem
and related issues | 9 pages, no figures. Born and von Neumann comments added, minor typos
corrected | null | null | null | quant-ph | null | Several theories have been advanced recently which appear to offer a
resolution to that portion of the measurement problem which previously dealt
with a possible reduction of the state vector in a subjective fashion by the
brain, mind or consciousness. It now appears, based on both biological and
mathematical analysis, that collapse of the wave function always takes place in
an objective fashion in the retinal rod-rhodopsin molecule, and that only
measured information is ever presented to the brain, mind or consciousness for
possible subjective analysis. The remaining portion of the measurement problem
has to do with the use and legitimacy of such terms as boundary (Heisenberg or
von Neumann cut), information, irreversible, measurement, microscopic,
macroscopic, observer (apparatus or measuring system), observed (measured
system) and wave function collapse. This portion of the measurement problem may
be resolved in two ways. First, by adopting Dirac's theory that it is nature
that makes the choice of measuremental result. Second, by the insertion of a
mesoscopic bridge between the microscopic and macroscopic worlds, in the
existing form of the rhodopsin molecule with its retinal and opsin components.
| [
{
"version": "v1",
"created": "Mon, 12 Feb 2007 18:57:17 GMT"
},
{
"version": "v2",
"created": "Wed, 14 Mar 2007 18:21:20 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Thaheld",
"Fred H.",
""
]
] |
quant-ph/0702115 | Gerard Milburn | G. J. Milburn | Coherent control of single photon states | Lecture given at the workshop on "Theoretical and Experimental
Foundations of Recent Quantum Technologies" Durban, July 2006. Submited to
Journal de Physique IV - Proceedings | null | 10.1140/epjst/e2008-00699-5 | null | quant-ph | null | We define a class of multi-mode single photon states suitable for quantum
information applications. We show how standard amplitude modulation techniques
may be used to control the pulse shape of single photon states.
| [
{
"version": "v1",
"created": "Mon, 12 Feb 2007 21:47:03 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Milburn",
"G. J.",
""
]
] |
quant-ph/0702116 | Maarten Van den Nest | M. Van den Nest, W. D\"ur, A. Miyake, H. J. Briegel | Fundamentals of universality in one-way quantum computation | 50 pages | New J. Phys. 9 204 (2007) | 10.1088/1367-2630/9/6/204 | null | quant-ph | null | We build a framework allowing for a systematic investigation of the issue:
"Which quantum states are universal resources for one-way quantum computation?"
We start by re-examining what is exactly meant by "universality" in quantum
computation, and what the implications are for universal one-way quantum
computation. Given the framework of a measurement-based quantum computer, where
quantum information is processed by local operations only, the most general
universal one-way quantum computer is one which is capable of accepting
arbitrary classical inputs and producing arbitrary quantum outputs--we refer to
this property as CQ-universality. We then show that a systematic study of
CQ-universality in one-way quantum computation is possible by identifying
entanglement features that must be present in every universal resource. These
insights are used to identify several states as being not universal, such as 1D
cluster states, W states, and ground states of non-critical 1D spin systems.
Our criteria are strengthened by considering the efficiency of a quantum
computation, and we find that entanglement measures must obey a certain scaling
law with the system size for all efficient universal resources. This again
leads to examples of non-universal resources, such as, e.g., ground states of
critical 1D spin systems. We also provide several examples of efficient
universal resources, namely graph states corresponding to hexagonal, triangular
and Kagome lattices. Finally, we consider the more general notion of encoded
CQ-universality, where quantum outputs are allowed to be produced in an encoded
form. Again we provide entanglement-based criteria for encoded universality.
Moreover, we present a general procedure to construct encoded universal
resources.
| [
{
"version": "v1",
"created": "Mon, 12 Feb 2007 22:01:03 GMT"
},
{
"version": "v2",
"created": "Tue, 31 Jul 2007 09:33:27 GMT"
}
] | 2007-07-31T00:00:00 | [
[
"Nest",
"M. Van den",
""
],
[
"Dür",
"W.",
""
],
[
"Miyake",
"A.",
""
],
[
"Briegel",
"H. J.",
""
]
] |
quant-ph/0702117 | Diego Dalvit | S. Spagnolo, D.A.R. Dalvit, and P.W. Milonni | Van der Waals Interactions in a Magneto-Dielectric Medium | 9 pages, 1 figure | Phys. Rev. A 75, 052117 (2007) | 10.1103/PhysRevA.75.052117 | null | quant-ph | null | The van der Waals interaction between two ground-state atoms is calculated
for two electrically or magnetically polarizable particles embedded in a
dispersive magneto-dielectric medium. Unlike previous calculations which infer
the atom-atom interaction from the dilute-medium limit of the macroscopic,
many-body van der Waals interaction, the interaction is calculated directly for
the system of two atoms in a magneto-dielectric medium. Two approaches are
presented, the first based on the quantized electromagnetic field in a
dispersive medium without absorption and the second on Green functions that
allow for absorption. We show that the correct van der Waals interactions are
obtained regardless of whether absorption in the host medium is taken into
account.
| [
{
"version": "v1",
"created": "Mon, 12 Feb 2007 22:09:17 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Spagnolo",
"S.",
""
],
[
"Dalvit",
"D. A. R.",
""
],
[
"Milonni",
"P. W.",
""
]
] |
quant-ph/0702118 | Adan Cabello | Adan Cabello | Six-qubit permutation-based decoherence-free orthogonal basis | REVTeX4, 5 pages | Phys. Rev. A 75 (2007) 020301(R) | 10.1103/PhysRevA.75.020301 | null | quant-ph | null | There is a natural orthogonal basis of the 6-qubit decoherence-free (DF)
space robust against collective noise. Interestingly, most of the basis states
can be obtained from one another just permuting qubits. This property: (a) is
useful for encoding qubits in DF subspaces, (b) allows the implementation of
the Bennett-Brassard 1984 (BB84) protocol in DF subspaces just permuting
qubits, which completes a the method for quantum key distribution using DF
states proposed by Boileau et al. [Phys. Rev. Lett. 92, 017901 (2004)], and (c)
points out that there is only one 6-qubit DF state which is essentially new
(not obtained by permutations) and therefore constitutes an interesting
experimental challenge.
| [
{
"version": "v1",
"created": "Mon, 12 Feb 2007 22:39:25 GMT"
}
] | 2009-07-28T00:00:00 | [
[
"Cabello",
"Adan",
""
]
] |
quant-ph/0702119 | Yury Bliokh P | K. Yu. Bliokh | On spin evolution in a time-dependent magnetic field: post-adiabatic
corrections and geometric phases | 10 pages, 1 figure, to appear in Phys. Lett. A | Phys.Lett.A372:204-209,2008 | 10.1016/j.physleta.2007.07.036 | null | quant-ph cond-mat.other | null | We examine both quantum and classical versions of the problem of spin
evolution in a slowly varying magnetic field. Main attention is given to the
first- and second-order adiabatic corrections in the case of in-plane
variations of the magnetic field. While the first-order correction relates to
the adiabatic Berry phase and Coriolis-type lateral deflection of the spin, the
second-order correction is shown to be responsible for the next-order geometric
phase and in-plain deflection. A comparison between different approaches,
including the exact (non-adiabatic) geometric phase, is presented.
| [
{
"version": "v1",
"created": "Mon, 12 Feb 2007 23:42:39 GMT"
},
{
"version": "v2",
"created": "Tue, 3 Jul 2007 16:55:41 GMT"
},
{
"version": "v3",
"created": "Sun, 22 Jul 2007 14:42:56 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Bliokh",
"K. Yu.",
""
]
] |
quant-ph/0702120 | Iris Reichenbach | Iris Reichenbach and Ivan H. Deutsch | Sideband cooling while preserving coherences in the nuclear spin state
in group-II-like atoms | 4 pages, 3 figures v4: minor changes in text, changes in the
references, published version | Phys. Rev. Lett. 99, 123001 (2007) | 10.1103/PhysRevLett.99.123001 | null | quant-ph | null | We propose a method for laser cooling group-II-like atoms without changing
the quantum state of their nuclear spins, thus preserving coherences that are
usually destroyed by optical pumping. As group-II-like atoms have a $^1S_0$
closed-shell ground state, nuclear spin and electronic degrees of freedom are
decoupled, allowing for independent manipulation. The hyperfine interaction
that couples these degrees of freedom in excited states can be suppressed
through the application of external magnetic fields. Our protocol employs
resolved-sideband cooling on the forbidden clock transition, $^1S_0 \to
{}^3P_0$, with quenching via coupling to the rapidly decaying $^1P_1$ state,
deep in the Paschen-Back regime. This makes it possible to laser cool neutral
atomic qubits without destroying the quantum information stored in their
nuclear spins, as shown in two examples, $^{171}$Yb and $^{87}$Sr.
| [
{
"version": "v1",
"created": "Tue, 13 Feb 2007 02:25:45 GMT"
},
{
"version": "v2",
"created": "Fri, 23 Feb 2007 05:28:04 GMT"
},
{
"version": "v3",
"created": "Mon, 4 Jun 2007 03:53:00 GMT"
},
{
"version": "v4",
"created": "Tue, 29 Jan 2008 00:33:44 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Reichenbach",
"Iris",
""
],
[
"Deutsch",
"Ivan H.",
""
]
] |
quant-ph/0702121 | Eleanor G. Rieffel | Eleanor G. Rieffel | Certainty and Uncertainty in Quantum Information Processing | Invited paper accompanying invited talk to AAAI Spring Symposium
2007. Comments, corrections, and suggestions would be most welcome | null | null | FXPAL-TR-06-017 | quant-ph | null | This survey, aimed at information processing researchers, highlights
intriguing but lesser known results, corrects misconceptions, and suggests
research areas. Themes include: certainty in quantum algorithms; the "fewer
worlds" theory of quantum mechanics; quantum learning; probability theory
versus quantum mechanics.
| [
{
"version": "v1",
"created": "Tue, 13 Feb 2007 02:25:36 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Rieffel",
"Eleanor G.",
""
]
] |
quant-ph/0702122 | Bertrand Girard | Wolfgang Merkel, Holger Mack, Wolfgang P. Schleich, Eric Lutz, Gerhard
G. Paulus, Bertrand Girard (LCAR) | Chirping a two-photon transition in a multi-state ladder | null | Physical Review A: Atomic, Molecular and Optical Physics 76, 02
(2007) 023417 | 10.1103/PhysRevA.76.023417 | null | quant-ph physics.atom-ph | null | We consider a two-photon transition in a specific ladder system driven by a
chirped laser pulse. In the weak field limit, we find that the excited state
probability amplitude arises due to interference of multiple quantum paths
which are weighted by quadratic phase factors. The excited state population has
the form of a Gauss sum which plays a prominent role in number theory.
| [
{
"version": "v1",
"created": "Tue, 13 Feb 2007 05:57:07 GMT"
}
] | 2007-09-12T00:00:00 | [
[
"Merkel",
"Wolfgang",
"",
"LCAR"
],
[
"Mack",
"Holger",
"",
"LCAR"
],
[
"Schleich",
"Wolfgang P.",
"",
"LCAR"
],
[
"Lutz",
"Eric",
"",
"LCAR"
],
[
"Paulus",
"Gerhard G.",
"",
"LCAR"
],
[
"Girard",
"Bertrand",
"",
"LCAR"
]
] |
quant-ph/0702123 | Simon Devitt Mr | Simon J. Devitt, Sonia G. Schirmer, Daniel K.L. Oi, Jared H. Cole,
Lloyd C.L. Hollenberg | Subspace Confinement: How good is your qubit? | 13 pages, 11 figures, accepted for publication in New Journal of
Physics | New J. Phys. 9, 384 (2007) | 10.1088/1367-2630/9/10/384 | null | quant-ph | null | The basic operating element of standard quantum computation is the qubit, an
isolated two-level system that can be accurately controlled, initialized and
measured. However, the majority of proposed physical architectures for quantum
computation are built from systems that contain much more complicated Hilbert
space structures. Hence, defining a qubit requires the identification of an
appropriate controllable two-dimensional sub-system. This prompts the obvious
question of how well a qubit, thus defined, is confined to this subspace, and
whether we can experimentally quantify the potential leakage into to states
outside the qubit subspace. In this paper we demonstrate that subspace leakage
can be quantitatively characterized using minimal theoretical assumptions by
examining the Fourier spectrum of the Rabi oscillation experiment.
| [
{
"version": "v1",
"created": "Tue, 13 Feb 2007 06:24:18 GMT"
},
{
"version": "v2",
"created": "Wed, 14 Feb 2007 23:16:02 GMT"
},
{
"version": "v3",
"created": "Wed, 3 Oct 2007 06:30:14 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Devitt",
"Simon J.",
""
],
[
"Schirmer",
"Sonia G.",
""
],
[
"Oi",
"Daniel K. L.",
""
],
[
"Cole",
"Jared H.",
""
],
[
"Hollenberg",
"Lloyd C. L.",
""
]
] |
quant-ph/0702124 | Philip Goyal Dr | Philip Goyal | An Information-Theoretic Approach to Quantum Theory, I: The Abstract
Quantum Formalism | 31 pages, 2 eps figures, revtex4. Comments welcome | null | null | null | quant-ph | null | In this paper and a companion paper, we attempt to systematically investigate
the possibility that the concept of information may enable a derivation of the
quantum formalism from a set of physically comprehensible postulates. To do so,
we formulate an abstract experimental set-up and a set of assumptions based on
generalizations of experimental facts that can be reasonably taken to be
representative of quantum phenomena, and on theoretical ideas and principles,
and show that it is possible to deduce the quantum formalism. In particular, we
show that it is possible to derive the abstract quantum formalism for
finite-dimensional quantum systems and the formal relations, such as the
canonical commutation relationships and Dirac's Poisson Bracket rule, that are
needed to apply the abstract formalism to particular systems of interest. The
concept of information, via an information-theoretic invariance principle,
plays a key role in the derivation, and gives rise to some of the central
structural features of the quantum formalism.
| [
{
"version": "v1",
"created": "Tue, 13 Feb 2007 09:56:19 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Goyal",
"Philip",
""
]
] |
quant-ph/0702125 | Igor B. Mekhov | Igor. B. Mekhov, Christoph Maschler, Helmut Ritsch | Probing quantum phases of ultracold atoms in optical lattices by
transmission spectra in cavity QED | 6 pages, 3 figures | Nature Phys. 3, 319 (2007) | 10.1038/nphys571 | null | quant-ph physics.atom-ph physics.optics | null | Studies of ultracold atoms in optical lattices link various disciplines,
providing a playground where fundamental quantum many-body concepts, formulated
in condensed-matter physics, can be tested in much better controllable atomic
systems, e.g., strongly correlated phases, quantum information processing.
Standard methods to measure quantum properties of Bose-Einstein condensates
(BECs) are based on matter-wave interference between atoms released from traps
which destroys the system. Here we propose a nondestructive method based on
optical measurements, and prove that atomic statistics can be mapped on
transmission spectra of a high-Q cavity. This can be extremely useful for
studying phase transitions between Mott insulator and superfluid states, since
various phases show qualitatively distinct light scattering. Joining the
paradigms of cavity quantum electrodynamics (QED) and ultracold gases will
enable conceptually new investigations of both light and matter at ultimate
quantum levels, which only recently became experimentally possible. Here we
predict effects accessible in such novel setups.
| [
{
"version": "v1",
"created": "Tue, 13 Feb 2007 12:28:13 GMT"
},
{
"version": "v2",
"created": "Thu, 22 Nov 2007 00:05:40 GMT"
}
] | 2007-11-22T00:00:00 | [
[
"Mekhov",
"Igor. B.",
""
],
[
"Maschler",
"Christoph",
""
],
[
"Ritsch",
"Helmut",
""
]
] |
quant-ph/0702126 | Masahiro Takeoka | Masahiro Takeoka and Masahide Sasaki | Conditional generation of an arbitrary superposition of coherent states | 7 pages, 5 figures | Phys. Rev. A 75, 064302 (2007) | 10.1103/PhysRevA.75.064302 | null | quant-ph | null | We present a scheme to conditionally generate an arbitrary superposition of a
pair of coherent states from a squeezed vacuum by means of the modified photon
subtraction where a coherent state ancilla and two on/off type detectors are
used. We show that, even including realistic imperfections of the detectors,
our scheme can generate a target state with a high fidelity. The amplitude of
the generated states can be amplified by conditional homodyne detections.
| [
{
"version": "v1",
"created": "Tue, 13 Feb 2007 13:42:16 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Takeoka",
"Masahiro",
""
],
[
"Sasaki",
"Masahide",
""
]
] |
quant-ph/0702127 | Ou Yong-Cheng | Yong-Cheng Ou and Heng Fan | Monogamy Inequality in terms of Negativity for Three-Qubit States | 5 pages, 3 figures, minor modifications are made | Physical Review A 75, 062308 (2007) | 10.1103/PhysRevA.75.062308 | null | quant-ph | null | We propose a new entanglement measure to quantify three qubits entanglement
in terms of negativity. A monogamy inequality analogous to
Coffman-Kundu-Wootters (CKW) inequality is established. This consequently leads
to a definition of residual entanglement, which is referred to as three-$\pi$
in order to distinguish from three-tangle. The three-$\pi$ is proved to be a
natural entanglement measure. By contrast to the three-tangle, it is shown that
the three-$\pi$ always gives greater than zero values for $W$ and GHZ classes,
implying there always exists three-way entanglement for them, and three-tangle
generally underestimates three-way entanglement of a given system. This
investigation will offer an alternative tool to understand genuine multipartite
entanglement.
| [
{
"version": "v1",
"created": "Tue, 13 Feb 2007 14:13:47 GMT"
},
{
"version": "v2",
"created": "Mon, 2 Apr 2007 12:19:18 GMT"
},
{
"version": "v3",
"created": "Tue, 3 Apr 2007 03:53:22 GMT"
},
{
"version": "v4",
"created": "Wed, 4 Apr 2007 04:14:15 GMT"
}
] | 2007-06-11T00:00:00 | [
[
"Ou",
"Yong-Cheng",
""
],
[
"Fan",
"Heng",
""
]
] |
quant-ph/0702128 | Carlo Rizzo | Juan Alberto Beswick (LCAR), Carlo Rizzo (LCAR) | Structure of the photon and magnetic field induced birefringence and
dichroism | null | Annales Fond.Broglie 33:31-43,2008 | null | null | quant-ph hep-ph | null | In this letter we show that the dichroism and ellipticity induced on a linear
polarized light beam by the presence of a magnetic field in vacuum can be
explained in the framework of the de Broglie's fusion model of a photon. In
this model it is assumed that the usual photon is the spin 1 state of a
particle-antiparticle bound state of two spin 1/2 fermions. The other S=0 state
is referred to as the \emph{second} photon. On the other hand, since no charged
particle neither particles having an electric dipole are considered, no effect
is predicted in the presence of electric fields and this model is not in
contradiction with star cooling data or solar axion search.
| [
{
"version": "v1",
"created": "Tue, 13 Feb 2007 15:52:34 GMT"
}
] | 2009-08-11T00:00:00 | [
[
"Beswick",
"Juan Alberto",
"",
"LCAR"
],
[
"Rizzo",
"Carlo",
"",
"LCAR"
]
] |
quant-ph/0702129 | Avraham Ben-Aroya | Avraham Ben-Aroya and Amnon Ta-Shma | Quantum expanders and the quantum entropy difference problem | 30 pages, 1 figure | null | null | null | quant-ph | null | We define quantum expanders in a natural way. We show that under certain
conditions classical expander constructions generalize to the quantum setting,
and in particular so does the Lubotzky, Philips and Sarnak construction of
Ramanujan expanders from Cayley graphs of the group PGL. We show that this
definition is exactly what is needed for characterizing the complexity of
estimating quantum entropies.
| [
{
"version": "v1",
"created": "Tue, 13 Feb 2007 15:53:15 GMT"
},
{
"version": "v2",
"created": "Thu, 19 Apr 2007 12:38:29 GMT"
},
{
"version": "v3",
"created": "Fri, 20 Apr 2007 03:43:02 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ben-Aroya",
"Avraham",
""
],
[
"Ta-Shma",
"Amnon",
""
]
] |
quant-ph/0702130 | Nicolas Brunner | Nicolas Brunner, Nicolas Gisin, Valerio Scarani and Christoph Simon | Detection loophole in asymmetric Bell experiments | 4 pages, 2 figures. Main result unchanged, wrong corollary removed | Phys. Rev. Lett., 98, 220403 (2007) | 10.1103/PhysRevLett.98.220403 | null | quant-ph | null | The problem of closing the detection loophole with asymmetric systems, such
as entangled atom-photon pairs, is addressed. We show that, for the Bell
inequality I_3322, a minimal detection efficiency of 43% can be tolerated for
one of the particles, if the other one is always detected. We also study the
influence of noise and discuss the prospects of experimental implementation.
| [
{
"version": "v1",
"created": "Tue, 13 Feb 2007 17:09:16 GMT"
},
{
"version": "v2",
"created": "Wed, 21 Feb 2007 16:03:47 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Brunner",
"Nicolas",
""
],
[
"Gisin",
"Nicolas",
""
],
[
"Scarani",
"Valerio",
""
],
[
"Simon",
"Christoph",
""
]
] |
quant-ph/0702131 | Masoud Mohseni | M. Mohseni, A. T. Rezakhani, D. A. Lidar | Quantum Process Tomography: Resource Analysis of Different Strategies | 15 pages, 5 figures, published version | Phys. Rev. A 77, 032322 (2008) | 10.1103/PhysRevA.77.032322 | null | quant-ph | null | Characterization of quantum dynamics is a fundamental problem in quantum
physics and quantum information science. Several methods are known which
achieve this goal, namely Standard Quantum Process Tomography (SQPT),
Ancilla-Assisted Process Tomography (AAPT), and the recently proposed scheme of
Direct Characterization of Quantum Dynamics (DCQD). Here, we review these
schemes and analyze them with respect to some of the physical resources they
require. Although a reliable figure-of-merit for process characterization is
not yet available, our analysis can provide a benchmark which is necessary for
choosing the scheme that is the most appropriate in a given situation, with
given resources. As a result, we conclude that for quantum systems where
two-body interactions are not naturally available, SQPT is the most efficient
scheme. However, for quantum systems with controllable two-body interactions,
the DCQD scheme is more efficient than other known QPT schemes in terms of the
total number of required elementary quantum operations.
| [
{
"version": "v1",
"created": "Tue, 13 Feb 2007 20:06:33 GMT"
},
{
"version": "v2",
"created": "Wed, 19 Mar 2008 19:04:04 GMT"
}
] | 2008-03-19T00:00:00 | [
[
"Mohseni",
"M.",
""
],
[
"Rezakhani",
"A. T.",
""
],
[
"Lidar",
"D. A.",
""
]
] |
quant-ph/0702132 | Alexander Stibor | A. Stibor, S. Kraft, T. Campey, D. Komma, A. G\"unther, J. Fort\'agh,
C. J. Vale, H. Rubinsztein-Dunlop, and C. Zimmermann | Calibration of a single atom detector for atomic micro chips | null | Phys. Rev. A 76, 033614 (2007) | 10.1103/PhysRevA.76.033614 | null | quant-ph | null | We experimentally investigate a scheme for detecting single atoms
magnetically trapped on an atom chip. The detector is based on the
photoionization of atoms and the subsequent detection of the generated ions. We
describe the characterization of the ion detector with emphasis on its
calibration via the correlation of ions with simultaneously generated
electrons. A detection efficiency of 47.8% (+-2.6%) is measured, which is
useful for single atom detection, and close to the limit allowing atom counting
with sub-Poissonian uncertainty.
| [
{
"version": "v1",
"created": "Tue, 13 Feb 2007 19:53:03 GMT"
}
] | 2014-05-16T00:00:00 | [
[
"Stibor",
"A.",
""
],
[
"Kraft",
"S.",
""
],
[
"Campey",
"T.",
""
],
[
"Komma",
"D.",
""
],
[
"Günther",
"A.",
""
],
[
"Fortágh",
"J.",
""
],
[
"Vale",
"C. J.",
""
],
[
"Rubinsztein-Dunlop",
"H.",
""
],
[
"Zimmermann",
"C.",
""
]
] |
quant-ph/0702133 | Dimitris G. Angelakis | Dimitris G. Angelakis and Alastair Kay | Cluster state quantum computation in coupled cavity arrays | Updated version that includes cluster state fidelity calculation and
protocol on minimizing the number of qubits neccesary for the implementation
of any algorithm | New J. Phys. 10 (2008) 023012. | null | null | quant-ph | null | Measurement-based quantum computation has revolutionized quantum information
processing, and the physical systems with which it can be implemented. One
simply needs the ability to prepare a particular state, known as the cluster
state, and subsequently to perform single-qubit measurements on it.
Nevertheless, a scalable implementation is yet to be realized. Here we propose
a hybrid light-matter system comprised of coupled cavities interacting with two
level systems. Utilising the stable, individually addressable, qubits resulting
from the localised long-lived atom-photon excitations, we demonstrate how to
use the natural system dynamics to `weave' these qubits into a cluster state
and propose the implementation of quantum algorithms employing just two rows of
qubits. Finally, we briefly discuss the prospects for experimental
implementation using atoms, quantum dots or Cooper pair boxes.
| [
{
"version": "v1",
"created": "Tue, 13 Feb 2007 20:58:42 GMT"
},
{
"version": "v2",
"created": "Tue, 17 Jul 2007 15:23:55 GMT"
}
] | 2008-02-15T00:00:00 | [
[
"Angelakis",
"Dimitris G.",
""
],
[
"Kay",
"Alastair",
""
]
] |
quant-ph/0702134 | Paul Slater | Paul B. Slater | Qubit-Qubit and Qubit-Qutrit Separability Functions and Probabilities | 36 pages, 3 figures; some new material included -- a quaternionic
two-qubit example, a new set of simplified integration limits for two-qubit
density matrices, and an analytically-derived (approximate) separability
function containing incomplete beta functions | null | null | null | quant-ph | null | We list in increasing order -- 1/3, 3/8, 2/5, 135 pi/1024, 16/(3 pi^2), 3
pi/16, 5/8, 105 pi/512, 2 - 435 pi/1024, 11/16, 1 -- a number of exact
two-qubit Hilbert-Schmidt (HS) separability probabilities, we are able to
compute. Each probability corresponds to a specific scenario -- a class of 4 x
4 density matrices (rho) with an m-subset (m<6) of its six off-diagonal pairs
of symmetrically located entries set to zero. Initially, we consider only
scenarios in which the (6-m) non-nullified pairs are real, but then permit them
to be complex (as well as quaternionic) in nature also. The general analytical
strategy we implement is based on the Bloore density matrix parameterization
(J. Phys. A, 9, 2059 [1976]), allowing us to conveniently reduce the
dimensionalities of required integrations. For each scenario, we identify a
certain univariate ``separability function'' S_{scenario}(nu), where nu =
rho_{11} rho_{44}/(rho_{22} rho_{33}). The integral over nu in [0,infty] of the
product of this function with a scenario-specific (marginal) jacobian function
J_{scenario}(nu) yields the HS {separable} volume (V^{HS}_{sep}). The ratio of
V^{HS}_{sep} to the HS total (entangled and non-entangled) volume, gives us the
HS scenario-specific separability probability. Among the possible forms that we
have so far determined for S_{scenario}(nu) are piecewise combinations of c, c
sqrt{nu} and c nu for nu in [0,1] and (in a dual manner) c, c/sqrt{nu} and c/nu
for nu in [1,infty]. We also obtain bivariate separability functions
S_{scenario)^{6 x 6}(nu_{1},nu_{2}} in the qubit-qutrit case, involving 6 x 6
density matrices, with ratio variables, nu_{1}= rho_{11} rho_{55}/(rho_{22}
rho_{44}), and nu_{2}= rho_{22} rho_{66}/(rho_{33} rho_{55}). Additionally, we
investigate parallel two-qutrit and three-qubit problems.
| [
{
"version": "v1",
"created": "Wed, 14 Feb 2007 17:00:26 GMT"
},
{
"version": "v2",
"created": "Thu, 8 Mar 2007 17:39:47 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Slater",
"Paul B.",
""
]
] |
quant-ph/0702135 | Th. M. Nieuwenhuizen | Armen E. Allahverdyan, Roger Balian, and Theo M. Nieuwenhuizen | The Quantum Measurement Process: Lessons from an Exactly Solvable Model | 13 pages, discussion of pre-measurement added. World Scientific
style. To appear in proceedings "Beyond The Quantum", Th.M. Nieuwenhuizen et
al, eds, (World Scientific, 2007) | null | 10.1142/9789812771186_0004 | null | quant-ph | null | The measurement of a spin-$\half$ is modeled by coupling it to an apparatus,
that consists of an Ising magnetic dot coupled to a phonon bath. Features of
quantum measurements are derived from the dynamical solution of the
measurement, regarded as a process of quantum statistical mechanics.
Schr\"odinger cat terms involving both the system and the apparatus, die out
very quickly, while the registration is a process taking the apparatus from its
initially metastable state to one of its stable final states. The occurrence of
Born probabilities can be inferred at the macroscopic level, by looking at the
pointer alone. Apparent non-unitary behavior of the measurement process is
explained by the arisal of small many particle correlations, that characterize
relaxation.
| [
{
"version": "v1",
"created": "Wed, 14 Feb 2007 16:34:45 GMT"
},
{
"version": "v2",
"created": "Wed, 28 Mar 2007 13:48:59 GMT"
}
] | 2017-08-23T00:00:00 | [
[
"Allahverdyan",
"Armen E.",
""
],
[
"Balian",
"Roger",
""
],
[
"Nieuwenhuizen",
"Theo M.",
""
]
] |
quant-ph/0702136 | Fernando Brandao | Fernando G.S.L. Brandao, Michal Horodecki, Martin B. Plenio, Shashank
Virmani | Remarks on the equivalence of full additivity and monotonicity for the
entanglement cost | 3 and a bit sides | Open Sys. Inf. Dyn., 14, page 333 (2007) | 10.1007/s11080-007-9056-0 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyse the relationship between the full additivity of the entanglement
cost and its full monotonicity under local operations and classical
communication. We show that the two properties are equivalent for the
entanglement cost. The proof works for the regularization of any convex,
subadditive, and asymptotically continuous entanglement monotone, and hence
also applies to the asymptotic relative entropy of entanglement.
| [
{
"version": "v1",
"created": "Wed, 14 Feb 2007 13:29:38 GMT"
},
{
"version": "v2",
"created": "Tue, 27 Aug 2013 07:33:18 GMT"
}
] | 2013-08-28T00:00:00 | [
[
"Brandao",
"Fernando G. S. L.",
""
],
[
"Horodecki",
"Michal",
""
],
[
"Plenio",
"Martin B.",
""
],
[
"Virmani",
"Shashank",
""
]
] |
quant-ph/0702137 | Shang-Bin Li | Shang-Bin Li, Justin Liu, Xu-Bo Zou, Guang-Can Guo | Nonclassicality of quantum excitation of classical coherent fields in
thermal environments | 10 pages, 5 figures, three references are added, and a brief
discussion of the possible applications of SPACSs in quantum information
processes has been added; Accepted by JOSA B | J. Opt. Soc. Am. B 25, 54 (2008) | 10.1364/JOSAB.25.000054 | null | quant-ph | null | The nonclassicality of photon-added coherent fields in the thermal channel is
investigated by exploring the volume of the negative part of the Wigner
function which reduces with the dissipative time. The Wigner functions become
positive when the decay time exceeds a threshold value. For the case of the
single photon-added coherent state, we derive the exact threshold values of
decay time in the thermal channel. For arbitrary partial negative Wigner
distribution function, a generic analytical relation between the mean photon
number of heat bath and the threshold value of decay time is presented.
Finally, the possible application of SPACSs in quantum computation has been
briefly discussed.
OCIS codes: 270.0270, 270.2500, 000.5490
| [
{
"version": "v1",
"created": "Wed, 14 Feb 2007 05:48:33 GMT"
},
{
"version": "v2",
"created": "Tue, 7 Aug 2007 03:13:45 GMT"
},
{
"version": "v3",
"created": "Fri, 19 Oct 2007 10:00:01 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Li",
"Shang-Bin",
""
],
[
"Liu",
"Justin",
""
],
[
"Zou",
"Xu-Bo",
""
],
[
"Guo",
"Guang-Can",
""
]
] |
quant-ph/0702138 | Kunihiro Kojima | Kunihiro Kojima and Akihisa Tomita | Quantum non-demolition measurement of photon-arrival using an
atom-cavity system | 12pages, 4figures, Submitted to Phys. Rev. A | Phys. Rev. A 75, 032320 (2007) | null | null | quant-ph | null | A simple and efficient quantum non-demolition measurement (QND) scheme is
proposed in which the arrival of a signal photon is detected without affecting
the qubit state. The proposed QND scheme functions even if the ancillary photon
is replaced with weak light composed of vacuum and one-photon states. Although
the detection scheme is designed for entanglement sharing applications, it is
also suitable for general purification of a single photon state.
| [
{
"version": "v1",
"created": "Wed, 14 Feb 2007 07:25:23 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Kojima",
"Kunihiro",
""
],
[
"Tomita",
"Akihisa",
""
]
] |
quant-ph/0702139 | Yuishi Takeno | Yuishi Takeno, Mitsuyoshi Yukawa, Hidehiro Yonezawa, Akira Furusawa | Observation of -9 dB quadrature squeezing with improvement of phase
stability in homodyne measurement | 4 pages, 4 figures | Optics Express 15, 4321 (2007) | 10.1364/OE.15.004321 | null | quant-ph | null | We observe -9.01$\pm$0.14 dB of squeezing and +15.12$\pm$0.14 dB of
antisqueezing with a local oscillator phase locked in homodyne measurement. In
reference [1], two main factors are pointed out which degrade the observed
squeezing level: phase fluctuation in homodyne measurement and intracavity
losses of an optical parametric oscillator for squeezing. We have improved the
phase stability of homodyne measurement and have reduced the intracavity
losses. We measure pump power dependences of the squeezing and antisqueezing
levels, which show good agreement with theoretical calculations taking account
of the phase fluctuation.
| [
{
"version": "v1",
"created": "Wed, 14 Feb 2007 07:26:58 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Takeno",
"Yuishi",
""
],
[
"Yukawa",
"Mitsuyoshi",
""
],
[
"Yonezawa",
"Hidehiro",
""
],
[
"Furusawa",
"Akira",
""
]
] |
quant-ph/0702140 | Amiram Ron | D. R. Fredkin, Amiram Ron | Slowing the Decay of an Excited Atom by the Presence of a Detector | null | null | null | null | quant-ph | null | The decay of an excited is shown to slow down in the presence of a photo
detector. This is similar to the behavior of an atom in a mistuned cavity, and
under the conditions of the quantum Zeno effect. No external perturbing field
is applied to measure the survival probability of the unstable state.
| [
{
"version": "v1",
"created": "Wed, 14 Feb 2007 09:18:49 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Fredkin",
"D. R.",
""
],
[
"Ron",
"Amiram",
""
]
] |
quant-ph/0702141 | Ramazan Sever | Sameer M. Ikhdair, Ramazan Sever | Exact solutions of the radial Schrodinger equation for some physical
potentials | 13 pages | CentralEur.J.Phys.5:516,2007 | 10.2478/s11534-007-0022-9 | null | quant-ph | null | By using an ansatz for the eigenfunction, we have obtained the exact
analytical solutions of the radial Schrodinger equation for the pseudoharmonic
and Kratzer potentials in two dimensions. The energy levels of all the bound
states are easily calculated from this eigenfunction ansatz. The normalized
wavefunctions are also obtained.
| [
{
"version": "v1",
"created": "Wed, 14 Feb 2007 09:29:16 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Ikhdair",
"Sameer M.",
""
],
[
"Sever",
"Ramazan",
""
]
] |
quant-ph/0702142 | Joerg Evers | M. Macovei, J. Evers, and C. H. Keitel | Strong-field spatial intensity-intensity correlations of light scattered
from regular structures of atoms | null | null | null | null | quant-ph | null | Photon correlations and cross-correlations of light scattered by a regular
structure of strongly driven atoms are investigated. At strong driving, the
scattered light separates into distinct spectral bands, such that each band can
be treated as independent, thus extending the set of observables. We focus on
second-order intensity-intensity correlation functions in two- and multi-atom
systems. We demonstrate that for a single two-photon detector as, e.g., in
lithography, increasing the driving field intensity leads to an increased
spatial resolution of the second-order two-atom interference pattern. We show
that the cross-correlations between photons emitted in the spectral sidebands
violate Cauchy-Schwartz inequalities, and that their emission ordering cannot
be predicted. Finally, the results are generalized for multi-particle
structures, where we find results different from those in a Dicke-type sample.
| [
{
"version": "v1",
"created": "Wed, 14 Feb 2007 09:47:49 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Macovei",
"M.",
""
],
[
"Evers",
"J.",
""
],
[
"Keitel",
"C. H.",
""
]
] |
quant-ph/0702143 | Antonio Soares de Castro | Tatiana R. Cardoso, Antonio S. de Castro | On the Threshold for the Pair Production and Localization of Spinless
Particles | 12 pages, in Portuguese | Rev.Bras.Ens.Fis.29:203-208,2007 | null | null | quant-ph | null | The one-dimensional Klein-Gordon equation is investigated with the most
general Lorentz structure for the external potentials. The analysis of the
scattering of particles in a step potential with an arbitrary mixing of vector
and scalar couplings reveals that the scalar coupling contributes for
increasing the threshold energy for the particle-antiparticle pair production.
Furthermore, it is shown that the pair production is only feasible whether the
vector coupling exceeds the scalar one. An apparent paradox concerning the
localization of a particle in an arbitrarily small region of space, due to the
presence of the scalar coupling, is solved by introducing the concept of
effective Compton wavelength.
| [
{
"version": "v1",
"created": "Wed, 14 Feb 2007 10:01:47 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Cardoso",
"Tatiana R.",
""
],
[
"de Castro",
"Antonio S.",
""
]
] |
quant-ph/0702144 | Charles Suggs | E. Farhi, J. Goldstone, S. Gutmann | A Quantum Algorithm for the Hamiltonian NAND Tree | 16 pages, 15 figures, v2 with run time improved to sqrt N by slight
sharpening of estimates in section 3 | null | null | MIT-CTP-3813 | quant-ph | null | We give a quantum algorithm for the binary NAND tree problem in the
Hamiltonian oracle model. The algorithm uses a continuous time quantum walk
with a run time proportional to sqrt N. We also show a lower bound of sqrt N
for the NAND tree problem in the Hamiltonian oracle model.
| [
{
"version": "v1",
"created": "Wed, 14 Feb 2007 18:10:15 GMT"
},
{
"version": "v2",
"created": "Thu, 22 Feb 2007 20:14:10 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Farhi",
"E.",
""
],
[
"Goldstone",
"J.",
""
],
[
"Gutmann",
"S.",
""
]
] |
quant-ph/0702145 | Guang Ping He | Hua-Zhong Li | On the consistency in the adiabatic theorem and quantum geometric phase | 7 pages | null | null | null | quant-ph | null | The recent discovery of inconsistency (MS inconsistency) in the adiabatic
approximation is discussed. In particular, the so-called, inconsistency in
Berry phase is analyzed. On the contrary to some authors, we found that the MS
inconsistency persisted and the so-called inconsistency in Berry phase does not
exist.
| [
{
"version": "v1",
"created": "Wed, 14 Feb 2007 18:39:06 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Li",
"Hua-Zhong",
""
]
] |
quant-ph/0702146 | Kurt Gibble | Russell A. Hart, Xinye Xu, Ronald Legere, & Kurt Gibble | A Quantum Scattering Interferometer | Corrected formatting and typos | Nature 446, 892-895 (19 April 2007) | 10.1038/nature05680 | null | quant-ph | null | The collision of two ultra-cold atoms results in a quantum-mechanical
superposition of two outcomes: each atom continues without scattering and each
atom scatters as a spherically outgoing wave with an s-wave phase shift. The
magnitude of the s-wave phase shift depends very sensitively on the interaction
between the atoms. Quantum scattering and the underlying phase shifts are
vitally important in many areas of contemporary atomic physics, including
Bose-Einstein condensates, degenerate Fermi gases, frequency shifts in atomic
clocks, and magnetically-tuned Feshbach resonances. Precise measurements of
quantum scattering phase shifts have not been possible until now because, in
scattering experiments, the number of scattered atoms depends on the s-wave
phase shifts as well as the atomic density, which cannot be measured precisely.
Here we demonstrate a fundamentally new type of scattering experiment that
interferometrically detects the quantum scattering phase shifts of individual
atoms. By performing an atomic clock measurement using only the scattered part
of each atom, we directly and precisely measure the difference of the s-wave
phase shifts for the two clock states in a density independent manner. Our
method will give the most direct and precise measurements of ultracold
atom-atom interactions and will place stringent limits on the time variations
of fundamental constants.
| [
{
"version": "v1",
"created": "Wed, 14 Feb 2007 19:42:23 GMT"
},
{
"version": "v2",
"created": "Fri, 2 Mar 2007 22:59:52 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Hart",
"Russell A.",
""
],
[
"Xu",
"Xinye",
""
],
[
"Legere",
"Ronald",
""
],
[
"Gibble",
"Kurt",
""
]
] |
quant-ph/0702147 | Matthew Grace | Matthew Grace, Constantin Brif, Herschel Rabitz, Ian A. Walmsley,
Robert L. Kosut, and Daniel A. Lidar | Optimal control of quantum gates and suppression of decoherence in a
system of interacting two-level particles | IOP LaTeX, 10 figures, 29 pages; Accepted for publication in the
Special Issue of the Journal of Physics B on Dynamical Control of
Entanglement and Decoherence by Field-Matter Interactions | J. Phys. B: At. Mol. Opt. Phys. 40, S103-S125 (2007) | 10.1088/0953-4075/40/9/S06 | null | quant-ph | null | Methods of optimal control are applied to a model system of interacting
two-level particles (e.g., spin-half atomic nuclei or electrons or two-level
atoms) to produce high-fidelity quantum gates while simultaneously negating the
detrimental effect of decoherence. One set of particles functions as the
quantum information processor, whose evolution is controlled by a
time-dependent external field. The other particles are not directly controlled
and serve as an effective environment, coupling to which is the source of
decoherence. The control objective is to generate target one- and two-qubit
unitary gates in the presence of strong environmentally-induced decoherence and
under physically motivated restrictions on the control field. The quantum-gate
fidelity, expressed in terms of a novel state-independent distance measure, is
maximized with respect to the control field using combined genetic and gradient
algorithms. The resulting high-fidelity gates demonstrate the feasibility of
precisely guiding the quantum evolution via optimal control, even when the
system complexity is exacerbated by environmental coupling. It is found that
the gate duration has an important effect on the control mechanism and
resulting fidelity. An analysis of the sensitivity of the gate performance to
random variations in the system parameters reveals a significant degree of
robustness attained by the optimal control solutions.
| [
{
"version": "v1",
"created": "Wed, 14 Feb 2007 20:02:35 GMT"
},
{
"version": "v2",
"created": "Mon, 16 Apr 2007 03:40:55 GMT"
}
] | 2009-12-23T00:00:00 | [
[
"Grace",
"Matthew",
""
],
[
"Brif",
"Constantin",
""
],
[
"Rabitz",
"Herschel",
""
],
[
"Walmsley",
"Ian A.",
""
],
[
"Kosut",
"Robert L.",
""
],
[
"Lidar",
"Daniel A.",
""
]
] |
quant-ph/0702148 | Kazuyuki Fujii | Kazuyuki Fujii (Yokohama City University) | Quantum Mechanics with Complex Time : A Comment to the Paper by Rajeev | Latex ; 7 pages ; 1 figure. A draft prepared for the coming Numazu
Meeting (6-8/March/2007) | The Bulletin of Yokohama City University, 58(2007) 49-54 | null | null | quant-ph math-ph math.MP | null | In (quant-ph/0701141) Rajeev studied quantization of the damped simple
harmonic oscillator and introduced a complex-valued Hamiltonian (which is
normal). In this note we point out that the quantization is interpreted as a
quantum mechanics with {\bf complex time}. We also present a problem on
quantization of classical control systems.
| [
{
"version": "v1",
"created": "Thu, 15 Feb 2007 01:40:25 GMT"
}
] | 2009-01-15T00:00:00 | [
[
"Fujii",
"Kazuyuki",
"",
"Yokohama City University"
]
] |
quant-ph/0702149 | Philip Goyal | Philip Goyal | An Information-Theoretic Approach to Quantum Theory, II: The Formal
Rules of Quantum Theory | 20 pages, 3 figures, revtex4. Comments welcome | null | null | null | quant-ph | null | In a companion paper (hereafter referred to as Paper I), we have presented an
attempt to derive the finite-dimensional abstract quantum formalism from a set
of physically comprehensible assumptions. In this paper, we formulate a
correspondence principle, the Average-Value Correspondence Principle, that
allows relations between measurement outcomes which are known to hold in a
classical model of a system to be systematically taken over into the quantum
model of the system. Using this principle, we derive the explicit form of the
temporal evolution operator (thereby completing the derivation of the abstract
quantum formalism begun in Paper I), and derive many of the formal rules (such
as operator rules, commutation relations, and Dirac's Poisson bracket rule)
that are needed to apply the abstract quantum formalism to model particular
physical systems.
| [
{
"version": "v1",
"created": "Thu, 15 Feb 2007 04:36:52 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Goyal",
"Philip",
""
]
] |
quant-ph/0702150 | Xiao-qiang Xi | Xiu-Lao Tian, Xiao-Qiang Xi | The Bell bases decomposition of a general N-qubit state Teleportation
through a non-maximally entangled quantum channel | Comments are welcome; [email protected] | null | null | null | quant-ph | null | We propose a method of the Bell bases decomposition to teleport an arbitrary
unknown N-qubit state through a nonmaximally entangled quantum channel, and
give the universal decomposition matrix of N-qubit. Using the decomposition
matrix, we can easily obtain the collapsed state at the receiver site. The
inverse matrix that the decomposition matrix is just the transformation matrix
that the receiver can manipulate. The decomposition matrix is a function of the
parameters of the quantum channel. After defining the sub-matrix of the quantum
channel, we find that the decomposition matrix is a tensor product of the
sub-matrixes.
| [
{
"version": "v1",
"created": "Thu, 15 Feb 2007 06:18:47 GMT"
},
{
"version": "v2",
"created": "Wed, 28 Feb 2007 12:54:16 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Tian",
"Xiu-Lao",
""
],
[
"Xi",
"Xiao-Qiang",
""
]
] |
quant-ph/0702151 | Mehmet Ko\c{c}ak | M Kocak and B Gonul | A search on Dirac equation | 9 pages | Chin. Phys. Lett. 24 (2007) 3024 | 10.1088/0256-307X/24/11/003 | null | quant-ph math-ph math.MP | null | The solutions, in terms of orthogonal polynomials, of Dirac equation with
analytically solvable potentials are investigated within a novel formalism by
transforming the relativistic equation into a Schrodinger like one. Earlier
results are discussed in a unified framework and certain solutions of a large
class of potentials are given.
| [
{
"version": "v1",
"created": "Thu, 15 Feb 2007 12:33:28 GMT"
},
{
"version": "v2",
"created": "Fri, 16 Feb 2007 09:44:17 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Kocak",
"M",
""
],
[
"Gonul",
"B",
""
]
] |
quant-ph/0702152 | Stefano Pironio | Antonio Acin, Nicolas Brunner, Nicolas Gisin, Serge Massar, Stefano
Pironio, Valerio Scarani | Device-independent security of quantum cryptography against collective
attacks | 5 pages, 1 figure. v2: minor modifications | Phys. Rev. Lett. 98, 230501 (2007) | 10.1103/PhysRevLett.98.230501 | null | quant-ph | null | We present the optimal collective attack on a Quantum Key Distribution (QKD)
protocol in the "device-independent" security scenario, where no assumptions
are made about the way the QKD devices work or on what quantum system they
operate. Our main result is a tight bound on the Holevo information between one
of the authorized parties and the eavesdropper, as a function of the amount of
violation of a Bell-type inequality.
| [
{
"version": "v1",
"created": "Thu, 15 Feb 2007 15:29:10 GMT"
},
{
"version": "v2",
"created": "Mon, 25 Jun 2007 09:52:31 GMT"
}
] | 2007-10-22T00:00:00 | [
[
"Acin",
"Antonio",
""
],
[
"Brunner",
"Nicolas",
""
],
[
"Gisin",
"Nicolas",
""
],
[
"Massar",
"Serge",
""
],
[
"Pironio",
"Stefano",
""
],
[
"Scarani",
"Valerio",
""
]
] |
quant-ph/0702153 | Guillaume Aubrun | Guillaume Aubrun (ICJ), Ion Nechita (ICJ) | Catalytic majorization and $\ell_p$ norms | null | Communications in Mathematical Physics 278 (2008) 133-144 | 10.1007/s00220-007-0382-4 | null | quant-ph | null | An important problem in quantum information theory is the mathematical
characterization of the phenomenon of quantum catalysis: when can the
surrounding entanglement be used to perform transformations of a jointly held
quantum state under LOCC (local operations and classical communication) ?
Mathematically, the question amounts to describe, for a fixed vector $y$, the
set $T(y)$ of vectors $x$ such that we have $x \otimes z \prec y \otimes z$ for
some $z$, where $\prec$ denotes the standard majorization relation. Our main
result is that the closure of $T(y)$ in the $\ell_1$ norm can be fully
described by inequalities on the $\ell_p$ norms: $\|x\|_p \leq \|y\|_p$ for all
$p \geq 1$. This is a first step towards a complete description of $T(y)$
itself. It can also be seen as a $\ell_p$-norm analogue of Ky Fan dominance
theorem about unitarily invariant norms. The proofs exploits links with another
quantum phenomenon: the possibiliy of multiple-copy transformations
($x^{\otimes n} \prec y^{\otimes n}$ for given $n$). The main new tool is a
variant of Cram\'er$ theorem on large deviations for sums of i.i.d. random
variables.
| [
{
"version": "v1",
"created": "Thu, 15 Feb 2007 12:48:57 GMT"
},
{
"version": "v2",
"created": "Mon, 18 Jun 2007 09:19:46 GMT"
}
] | 2013-09-19T00:00:00 | [
[
"Aubrun",
"Guillaume",
"",
"ICJ"
],
[
"Nechita",
"Ion",
"",
"ICJ"
]
] |
quant-ph/0702154 | Ion Nechita | Ion Nechita (ICJ) | Asymptotics of random density matrices | null | Pacific Journal of Mathematics 8, 8 (2007) 1521-1538 | 10.1007/s00023-007-0345-5 | null | quant-ph | null | We investigate random density matrices obtained by partial tracing larger
random pure states. We show that there is a strong connection between these
random density matrices and the Wishart ensemble of random matrix theory. We
provide asymptotic results on the behavior of the eigenvalues of random density
matrices, including convergence of the empirical spectral measure. We also
study the largest eigenvalue (almost sure convergence and fluctuations).
| [
{
"version": "v1",
"created": "Thu, 15 Feb 2007 12:50:00 GMT"
},
{
"version": "v2",
"created": "Mon, 18 Jun 2007 11:55:13 GMT"
},
{
"version": "v3",
"created": "Tue, 19 Jun 2007 09:32:32 GMT"
}
] | 2009-05-14T00:00:00 | [
[
"Nechita",
"Ion",
"",
"ICJ"
]
] |
quant-ph/0702155 | Alan Leung | Alan W. Leung and Peter W. Shor | Entanglement purification with two-way classical communication | 10 pages with 4 figures, references added | null | null | null | quant-ph | null | We present an improved protocol for entanglement purification of bipartite
mixed states. The protocol requires two-way classical communication and hence
implies an improved lower bound on the quantum capacity with two-way classical
communication of the quantum depolarizing channel.
| [
{
"version": "v1",
"created": "Thu, 15 Feb 2007 14:32:39 GMT"
},
{
"version": "v2",
"created": "Fri, 16 Feb 2007 18:36:25 GMT"
},
{
"version": "v3",
"created": "Wed, 21 Feb 2007 21:41:34 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Leung",
"Alan W.",
""
],
[
"Shor",
"Peter W.",
""
]
] |
quant-ph/0702156 | Alan Leung | Alan W. Leung and Peter W. Shor | Adaptive Entanglement Purification Protocols with Two-way Classical
Communication | 4 pages with 7 figures, references added | null | null | null | quant-ph | null | We present a family of entanglement purification protocols that generalize
four previous methods, namely the recurrence method, the modified recurrence
method, and the two methods proposed by Maneva-Smolin and Leung-Shor. We will
show that this family of protocols have improved yields over a wide range of
initial fidelities F, and hence imply new lower bounds on the quantum capacity
assisted by two-way classical communication of the quantum depolarizing
channel. In particular, the yields of these protocols are higher than the yield
of universal hashing for F less than 0.993 and as F goes to 1.
| [
{
"version": "v1",
"created": "Thu, 15 Feb 2007 14:36:50 GMT"
},
{
"version": "v2",
"created": "Fri, 16 Feb 2007 18:38:18 GMT"
},
{
"version": "v3",
"created": "Wed, 28 Feb 2007 19:55:15 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Leung",
"Alan W.",
""
],
[
"Shor",
"Peter W.",
""
]
] |
quant-ph/0702157 | Christopher Gaul | Christopher Gaul and Helmut B\"uttner | Quantum Mechanical Heat Transport in Disordered Harmonic Chains | 12 pages, 15 figures | Phys. Rev. E 76, 011111 (2007) | 10.1103/PhysRevE.76.011111 | null | quant-ph cond-mat.stat-mech | null | We investigate the mechanism of heat conduction in ordered and disordered
harmonic onedimensional chains within the quantum mechanical Langevin method.
In the case of the disordered chains we find indications for normal heat
conduction which means that there is a finite temperature gradient but we
cannot clearly decide whether the heat resistance increases linearly with the
chain length. Furthermore we observe characteristic quantum mechanical features
like Bose-Einstein statistics of the occupation numbers of the normal modes,
freezing of the heat conductivity and the influence of the entanglement within
the chain on the current. For the ordered chain we recover some classical
results like a vanishing temperature gradient and a heat flux independent of
the length of the chain.
| [
{
"version": "v1",
"created": "Thu, 15 Feb 2007 16:56:08 GMT"
},
{
"version": "v2",
"created": "Tue, 19 Jun 2007 13:16:10 GMT"
},
{
"version": "v3",
"created": "Fri, 6 Jul 2007 15:28:09 GMT"
}
] | 2007-07-18T00:00:00 | [
[
"Gaul",
"Christopher",
""
],
[
"Büttner",
"Helmut",
""
]
] |
quant-ph/0702158 | Arjendu Pattanayak | Arnaldo Gammal and Arjendu K. Pattanayak | Quantum entropy dynamics for chaotic systems beyond the classical limit | 4 pages, 2 figs. Phys Rev E (to appear) | null | null | null | quant-ph | null | The entropy production rate for an open quantum system with a classically
chaotic limit has been previously argued to be independent of $\hbar$ and $D$,
the parameter denoting coupling to the environment, and to be equal to the sum
of generalized Lyapunov exponents, with these results applying in the
near-classical regime. We present results for a specific system going well
beyond earlier work, considering how these dynamics are altered for the Duffing
problem by changing $\hbar,D$ and show that the entropy dynamics have a
transition from classical to quantum behavior that scales, at least for a
finite time, as a function of $\hbar^2/D$.
| [
{
"version": "v1",
"created": "Thu, 15 Feb 2007 17:48:42 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gammal",
"Arnaldo",
""
],
[
"Pattanayak",
"Arjendu K.",
""
]
] |
quant-ph/0702159 | Adam Steele | A.V. Steele, L. R. Churchill, P. F. Griffin and M. S. Chapman | Photoionization and Photoelectric Loading of Barium Ion Traps | 5 pages, Accepted to PRA 3/20/2007 -fixed typo -clarified figure 3
caption -added reference [15] | null | 10.1103/PhysRevA.75.053404 | null | quant-ph physics.atom-ph | null | Simple and effective techniques for loading barium ions into linear Paul
traps are demonstrated. Two-step photoionization of neutral barium is achieved
using a weak intercombination line (6s2 1S0 <-> 6s6p 3P1, 791 nm) followed by
excitation above the ionization threshold using a nitrogen gas laser (337 nm).
Isotopic selectivity is achieved by using a near Doppler-free geometry for
excitation of the triplet 6s6p 3P1 state. Additionally, we report a
particularly simple and efficient trap loading technique that employs an
in-expensive UV epoxy curing lamp to generate photoelectrons.
| [
{
"version": "v1",
"created": "Thu, 15 Feb 2007 20:29:11 GMT"
},
{
"version": "v2",
"created": "Thu, 22 Mar 2007 17:29:29 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Steele",
"A. V.",
""
],
[
"Churchill",
"L. R.",
""
],
[
"Griffin",
"P. F.",
""
],
[
"Chapman",
"M. S.",
""
]
] |
quant-ph/0702160 | Andrew M. Childs | Andrew M. Childs, Richard Cleve, Stephen P. Jordan, David Yonge-Mallo | Discrete-query quantum algorithm for NAND trees | 2 pages. v2: updated name of one author | Theory of Computing, Vol. 5 (2009) 119-123 | 10.4086/toc.2009.v005a005 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently, Farhi, Goldstone, and Gutmann gave a quantum algorithm for
evaluating NAND trees that runs in time O(sqrt(N log N)) in the Hamiltonian
query model. In this note, we point out that their algorithm can be converted
into an algorithm using O(N^{1/2 + epsilon}) queries in the conventional
quantum query model, for any fixed epsilon > 0.
| [
{
"version": "v1",
"created": "Fri, 16 Feb 2007 20:56:11 GMT"
},
{
"version": "v2",
"created": "Fri, 6 Sep 2019 20:26:38 GMT"
}
] | 2019-09-10T00:00:00 | [
[
"Childs",
"Andrew M.",
""
],
[
"Cleve",
"Richard",
""
],
[
"Jordan",
"Stephen P.",
""
],
[
"Yonge-Mallo",
"David",
""
]
] |
quant-ph/0702161 | Carlos Pineda | C. Pineda, T. Gorin, and T. H. Seligman | Decoherence of two qubit systems: A random matrix description | 32 pages, 11 figures | New J. Phys. 9, 106,(2007) | 10.1088/1367-2630/9/4/106 | null | quant-ph cond-mat.stat-mech | null | We study decoherence of two non-interacting qubits. The environment and its
interaction with the qubits are modelled by random matrices. Decoherence,
measured in terms of purity, is calculated in linear response approximation.
Monte Carlo simulations illustrate the validity of this approximation and of
its extension by exponentiation. The results up to this point are also used to
study one qubit decoherence. Purity decay of entangled and product states are
qualitatively similar though for the latter case it is slower. Numerical
studies for a Bell pair as initial state reveal a one to one correspondence
between its decoherence and its internal entanglement decay. For strong and
intermediate coupling to the environment this correspondence agrees with the
one for Werner states. In the limit of a large environment the evolution
induces a unital channel in the two qubits, providing a partial explanation for
the relation above.
| [
{
"version": "v1",
"created": "Thu, 15 Feb 2007 21:19:15 GMT"
}
] | 2007-11-22T00:00:00 | [
[
"Pineda",
"C.",
""
],
[
"Gorin",
"T.",
""
],
[
"Seligman",
"T. H.",
""
]
] |
quant-ph/0702162 | P. W. H. Pinkse | T. Puppe, I. Schuster, A. Grothe, A. Kubanek, K. Murr, P.W.H. Pinkse,
and G. Rempe | Trapping and observing single atoms in the dark | null | Phys. Rev. Lett. 99, 013002 (2007) | 10.1103/PhysRevLett.99.013002 | null | quant-ph | null | A single atom strongly coupled to a cavity mode is stored by
three-dimensional confinement in blue-detuned cavity modes of different
longitudinal and transverse order. The vanishing light intensity at the trap
center reduces the light shift of all atomic energy levels. This is exploited
to detect a single atom by means of a dispersive measurement with 95%
confidence in 0.010 ms, limited by the photon-detection efficiency. As the atom
switches resonant cavity transmission into cavity reflection, the atom can be
detected while scattering about one photon.
| [
{
"version": "v1",
"created": "Thu, 15 Feb 2007 22:07:11 GMT"
},
{
"version": "v2",
"created": "Tue, 17 Apr 2007 19:54:11 GMT"
}
] | 2007-08-06T00:00:00 | [
[
"Puppe",
"T.",
""
],
[
"Schuster",
"I.",
""
],
[
"Grothe",
"A.",
""
],
[
"Kubanek",
"A.",
""
],
[
"Murr",
"K.",
""
],
[
"Pinkse",
"P. W. H.",
""
],
[
"Rempe",
"G.",
""
]
] |
quant-ph/0702163 | Sharly Fleischer | Sharly Fleischer, Ilya. Sh. Averbukh, Yehiam Prior | Selective Rotational Excitation of Molecular Isotopes and Nuclear Spin
Isomers | 23 pages, 13 figures | null | null | null | quant-ph | null | Following excitation by a strong ultra-short laser pulse, molecules develop
coordinated rotational motion, exhibiting transient alignment along the
direction of the laser electric field, followed by periodic full and fractional
revivals that depend on the molecular rotational constants. In mixtures, the
different species undergo similar rotational dynamics, all starting together
but evolving differently with each demonstrating its own periodic revival
cycles. For a bimolecular mixture of linear molecules, at predetermined times,
one species may attain a maximally aligned state while the other is
anti-aligned (i.e. molecular axes are confined in a plane perpendicular to the
laser electric field direction). By a properly timed second laser pulse, the
rotational excitation of the undesired species may be almost completely removed
leaving only the desired species to rotate and periodically realign, thus
facilitating further selective manipulations by polarized light. In this paper,
such double excitation schemes are demonstrated for mixtures of molecular
isotopes (isotopologues) and for nuclear spin isomers.
| [
{
"version": "v1",
"created": "Thu, 15 Feb 2007 22:10:09 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Fleischer",
"Sharly",
""
],
[
"Averbukh",
"Ilya. Sh.",
""
],
[
"Prior",
"Yehiam",
""
]
] |
quant-ph/0702164 | Carlos Pineda | Carlos Pineda, Toma\v{z} Prosen | Non-universal level statistics in a chaotic quantum spin chain | 6 pages, 7 figures | Phys. Rev. E 76, 061127 (2007) | 10.1103/PhysRevE.76.061127 | null | quant-ph | null | We study the level statistics of an interacting multi-qubit system, namely
the kicked Ising spin chain, in the regime of quantum chaos. Long range
quasi-energy level statistics show effects analogous to the ones observed in
semi-classical systems due to the presence of classical periodic orbits, while
short range level statistics display perfect statistical agreement with random
matrix theory. Even though our system possesses no classical limit, our result
suggest existence of an important non-universal system specific behavior at
short time scale, which clearly goes beyond finite size effects in random
matrix theory.
| [
{
"version": "v1",
"created": "Thu, 15 Feb 2007 23:23:30 GMT"
}
] | 2008-01-20T00:00:00 | [
[
"Pineda",
"Carlos",
""
],
[
"Prosen",
"Tomaž",
""
]
] |
quant-ph/0702165 | Hyunseok Jeong | Magdalena Stobi\'nska, Hyunseok Jeong and Timothy C. Ralph | Violation of Bell's inequality using classical measurements and
non-linear local operations | 6 pages, 5 figures, to be published in Phys. Rev. A | Phys. Rev. A 75, 052105 (2007) | 10.1103/PhysRevA.75.052105 | null | quant-ph | null | We find that Bell's inequality can be significantly violated (up to
Tsirelson's bound) with two-mode entangled coherent states using only homodyne
measurements. This requires Kerr nonlinear interactions for local operations on
the entangled coherent states. Our example is a demonstration of
Bell-inequality violations using classical measurements. We conclude that
entangled coherent states with coherent amplitudes as small as 0.842 are
sufficient to produce such violations.
| [
{
"version": "v1",
"created": "Fri, 16 Feb 2007 09:59:55 GMT"
},
{
"version": "v2",
"created": "Sun, 25 Mar 2007 14:22:22 GMT"
}
] | 2007-06-13T00:00:00 | [
[
"Stobińska",
"Magdalena",
""
],
[
"Jeong",
"Hyunseok",
""
],
[
"Ralph",
"Timothy C.",
""
]
] |
quant-ph/0702166 | Francesco Buscemi Dr | Francesco Buscemi, Masahito Hayashi, and Michal Horodecki | Global information balance in quantum measurements | Final version to appear on Physical Review Letters | Phys. Rev. Lett. 100, 210504 (2008) | 10.1103/PhysRevLett.100.210504 | null | quant-ph | null | We perform an information-theoretical analysis of quantum measurement
processes and obtain the global information balance in quantum measurements, in
the form of a closed chain equation for quantum mutual entropies. Our balance
provides a tight and general entropic information-disturbance trade-off, and
explains the physical mechanism underlying it. Finally, the single-outcome
case, that is, the case of measurements with post-selection, is briefly
discussed.
| [
{
"version": "v1",
"created": "Fri, 16 Feb 2007 09:05:46 GMT"
},
{
"version": "v2",
"created": "Mon, 26 Feb 2007 12:50:23 GMT"
},
{
"version": "v3",
"created": "Mon, 23 Apr 2007 03:25:08 GMT"
},
{
"version": "v4",
"created": "Wed, 14 Nov 2007 02:42:42 GMT"
},
{
"version": "v5",
"created": "Fri, 9 May 2008 00:28:45 GMT"
}
] | 2008-06-10T00:00:00 | [
[
"Buscemi",
"Francesco",
""
],
[
"Hayashi",
"Masahito",
""
],
[
"Horodecki",
"Michal",
""
]
] |
quant-ph/0702167 | Taksu Cheon | Tsubasa Ichikawa, Izumi Tsutsui, Taksu Cheon | Quantum Game Theory Based on the Schmidt Decomposition | 40 pages, 9 figures, PlainTeX | Journal of Physics A: Mathematical and Theoretical 41 (2008)
135303 (29p) | 10.1088/1751-8113/41/13/135303 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a novel formulation of quantum game theory based on the Schmidt
decomposition, which has the merit that the entanglement of quantum strategies
is manifestly quantified. We apply this formulation to 2-player, 2-strategy
symmetric games and obtain a complete set of quantum Nash equilibria. Apart
from those available with the maximal entanglement, these quantum Nash
equilibria are extensions of the Nash equilibria in classical game theory. The
phase structure of the equilibria is determined for all values of entanglement,
and thereby the possibility of resolving the dilemmas by entanglement in the
game of Chicken, the Battle of the Sexes, the Prisoners' Dilemma, and the Stag
Hunt, is examined. We find that entanglement transforms these dilemmas with
each other but cannot resolve them, except in the Stag Hunt game where the
dilemma can be alleviated to a certain degree.
| [
{
"version": "v1",
"created": "Fri, 16 Feb 2007 12:48:15 GMT"
},
{
"version": "v2",
"created": "Wed, 30 Jan 2013 04:59:23 GMT"
}
] | 2013-01-31T00:00:00 | [
[
"Ichikawa",
"Tsubasa",
""
],
[
"Tsutsui",
"Izumi",
""
],
[
"Cheon",
"Taksu",
""
]
] |
quant-ph/0702168 | Perry Rice | M. L. Terraciano, R. Olson Knell, D. L. Freimund, L. A. Orozco, J. P.
Clemens, and P. R. Rice | Enhanced Spontaneous Emission Into The Mode Of A Cavity QED System | 9 pages, 2 figures, to appear in May 2007 Optics Letters | null | 10.1364/OL.32.000982 | null | quant-ph | null | We study the light generated by spontaneous emission into a mode of a cavity
QED system under weak excitation of the orthogonally polarized mode. Operating
in the intermediate regime of cavity QED with comparable coherent and
decoherent coupling constants, we find an enhancement of the emission into the
undriven cavity mode by more than a factor of 18.5 over that expected by the
solid angle subtended by the mode. A model that incorporates three atomic
levels and two polarization modes quantitatively explains the observations.
| [
{
"version": "v1",
"created": "Fri, 16 Feb 2007 13:39:10 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Terraciano",
"M. L.",
""
],
[
"Knell",
"R. Olson",
""
],
[
"Freimund",
"D. L.",
""
],
[
"Orozco",
"L. A.",
""
],
[
"Clemens",
"J. P.",
""
],
[
"Rice",
"P. R.",
""
]
] |
quant-ph/0702169 | Javier Rodriguez-Laguna | Javier Rodriguez-Laguna | Quantum wavefunction annealing of spin glasses | Accepted for publication in JSTAT | J. Stat. Mech. (2007) P05008 | 10.1088/1742-5468/2007/05/P05008 | null | quant-ph cond-mat.dis-nn | null | A technique inspired on quantum annealing is proposed in order to obtain the
classical ground state of a spin-glass by tracking the full wavefunction of a
given system within the subspace of matrix product states (MPS), using the
density matrix renormalization group (DMRG). The technique is exemplified
within the problem of obtention of the classical ground state of an Ising spin
glass on ladder geometries. Its performance is evaluated and related to the
entanglement entropy.
| [
{
"version": "v1",
"created": "Fri, 16 Feb 2007 17:14:45 GMT"
},
{
"version": "v2",
"created": "Tue, 17 Apr 2007 10:37:13 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Rodriguez-Laguna",
"Javier",
""
]
] |
quant-ph/0702170 | Hermann Uys | H. Uys and P. Meystre | Quantum states for Heisenberg-limited interferometry | Published version, Updated discussion on N00N states, 11 pages, 6
figures | Physical Review A 76, 013804, (2007) | 10.1103/PhysRevA.76.013804 | null | quant-ph | null | The phase resolution of interferometers is limited by the so-called
Heisenberg limit, which states that the optimum phase sensitivity is inversely
proportional to the number of interfering particles N, a 1/sqrt{N} improvement
over the standard quantum limit. We have used simulated annealing, a global
optimization strategy, to systematically search for quantum interferometer
input states that approach the Heisenberg limited uncertainty in estimates of
the interferometer phase shift. We compare the performance of these states to
that of other non-classical states already known to yield Heisenberg limited
uncertainty.
| [
{
"version": "v1",
"created": "Fri, 16 Feb 2007 17:47:47 GMT"
},
{
"version": "v2",
"created": "Tue, 20 Feb 2007 17:39:50 GMT"
},
{
"version": "v3",
"created": "Thu, 19 Jul 2007 21:59:34 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Uys",
"H.",
""
],
[
"Meystre",
"P.",
""
]
] |
quant-ph/0702171 | Thomas Jordan | Thomas F. Jordan | Why quantum dynamics is linear | From talks, 15 pages | J.Phys.Conf.Ser.196:012010,2009 | 10.1088/1742-6596/196/1/012010 | null | quant-ph | null | Quantum dynamics is linear. How do we know? From theory or experiment? The
history of this question is reviewed. Nonlinear generalizations of quantum
mechanics have been proposed. They predict small but clear nonlinear effects,
which very accurate experiments have not seen. Is there a reason in principle
why nonlinearity is not found? Is it impossible? Does quantum dynamics have to
be linear? Attempts to prove this have not been decisive, because either their
assumptions are not compelling or their arguments are not conclusive. The
question has been left unsettled. There is a simple answer, based on a simple
assumption. It was found in two steps separated by 44 years. They are steps
back to simpler and more compelling assumptions. A proof of the assumptions of
the Wigner-Bargmann proof has been known since 1962. It assumes that the maps
of density matrices in time are linear. For this step, it is also assumed that
density matrices are mapped one-to-one onto density matrices. An alternative is
to assume that pure states are mapped one-to-one onto pure states and that
entropy does not decrease. In a step taken in 2006, it is proved that the maps
of density matrices in time are linear. It is assumed, as in the earlier step,
that at each time the physical quantities and states are described by the usual
linear structures of quantum mechanics, so the question is only about how
things change in time. Beyond that, the proof assumes only that the dynamics
does not depend on anything outside the system, but must allow the system to be
described as part of a larger system.
| [
{
"version": "v1",
"created": "Fri, 16 Feb 2007 17:59:23 GMT"
}
] | 2010-01-06T00:00:00 | [
[
"Jordan",
"Thomas F.",
""
]
] |
quant-ph/0702172 | Demetris Ghikas Dr. | George Stamatiou, Demetris P.K. Ghikas | Quantum Entanglement dependence on bifurcations and scars in non
autonomous systems. The case of Quantum Kicked Top | 14 pages, 6 figures in separate ps files, submitted for publication | null | 10.1016/j.physleta.2007.04.003 | null | quant-ph | null | Properties related to entanglement in quantum systems, are known to be
associated with distinct properties of the corresponding classical systems, as
for example stability, integrability and chaos. This means that the detailed
topology, both local and global, of the classical phase space may reveal, or
influence, the entangling power of the quantum system. As it has been shown in
the literature, the bifurcation points, in autonomous dynamical systems, play a
crucial role for the onset of entanglement. Similarly, the existence of scars
among the quantum states seems to be a factor in the dynamics of entanglement.
Here we study these issues for a non-autonomous system, the Quantum Kicked Top,
as a collective model of a multi-qubit system. Using the bifurcation diagram of
the corresponding classical limit (the Classical Kicked Top), we analyzed the
pair-wise and the bi-partite entanglement of the qubits and their relation to
scars, as a function of the critical parameter of the system. We found that the
pair-wise entanglement and pair-wise negativity show a strong maximum precisely
at the bifurcation points, while the bi-partite entanglement changes slope at
these points. We have also investigated the connection between entanglement and
the fixed points on the branch of the bifurcation diagram between the two first
bifurcation points and we found that the entanglement measures take their
extreme values precisely on these points. We conjecture that our results on
this behaviour of entanglement is generic for many quantum systems with a
non-linear classical analogue.
| [
{
"version": "v1",
"created": "Fri, 16 Feb 2007 18:19:02 GMT"
},
{
"version": "v2",
"created": "Tue, 20 Feb 2007 16:14:31 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Stamatiou",
"George",
""
],
[
"Ghikas",
"Demetris P. K.",
""
]
] |
quant-ph/0702173 | Philip Feinsilver | Philip Feinsilver, Jerzy Kocik | Krawtchouk matrices from classical and quantum random walks | There is a notational change (from Phi to K) from the published
version | Contemporary Mathematics, Volume 287 (2001) 83-96 | null | null | quant-ph | null | Krawtchouk's polynomials occur classically as orthogonal polynomials with
respect to the binomial distribution. They may be also expressed in the form of
matrices, that emerge as arrays of the values that the polynomials take. The
algebraic properties of these matrices provide a very interesting and
accessible example in the approach to probability theory known as quantum
probability. First it is noted how the Krawtchouk matrices are connected to the
classical symmetric Bernoulli random walk. And we show how to derive Krawtchouk
matrices in the quantum probability context via tensor powers of the elementary
Hadamard matrix. Then connections with the classical situation are shown by
calculating expectation values in the quantum case.
| [
{
"version": "v1",
"created": "Fri, 16 Feb 2007 20:52:00 GMT"
}
] | 2011-02-11T00:00:00 | [
[
"Feinsilver",
"Philip",
""
],
[
"Kocik",
"Jerzy",
""
]
] |
quant-ph/0702174 | Arjendu Pattanayak | Arie Kapulkin and Arjendu K. Pattanayak | Non-monotonicity in the quantum-classical transition: Chaos induced by
quantum effects | 4 pages; presentation modified significantly to demonstrate that
quantum effects are indeed responsible for the `anomalous' chaos. 2 figures
added | null | 10.1103/PhysRevLett.101.074101 | null | quant-ph | null | The transition from classical to quantum behavior for chaotic systems is
understood to be accompanied by the suppression of chaotic effects as the
relative size of $\hbar$ is increased. We show evidence to the contrary in the
behavior of the quantum trajectory dynamics of a dissipative quantum chaotic
system, the double-well Duffing oscillator. The classical limit in the case
considered has regular behavior, but as the effective $\hbar$ is increased we
see chaotic behavior. This chaos then disappears deeper into the quantum
regime, which means that the quantum-classical transition in this case is
non-monotonic in $\hbar$.
| [
{
"version": "v1",
"created": "Fri, 16 Feb 2007 21:12:32 GMT"
},
{
"version": "v2",
"created": "Wed, 8 Aug 2007 16:15:19 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Kapulkin",
"Arie",
""
],
[
"Pattanayak",
"Arjendu K.",
""
]
] |
quant-ph/0702175 | David Hucul | D. Hucul, M. Yeo, W.K. Hensinger, J. Rabchuk, S. Olmschenk, C. Monroe | On the Transport of Atomic Ions in Linear and Multidimensional Ion Trap
Arrays | 72 pages, 35 figures. to appear in the Journal of Quantum Information
and Computation, vol 8, no. 6&7, pg. 501 (2008) | null | null | null | quant-ph | null | Trapped atomic ions have become one of the most promising architectures for a
quantum computer, and current effort is now devoted to the transport of trapped
ions through complex segmented ion trap structures in order to scale up to much
larger numbers of trapped ion qubits. This paper covers several important
issues relevant to ion transport in any type of complex multidimensional rf
(Paul) ion trap array. We develop a general theoretical framework for the
application of time-dependent electric fields to shuttle laser-cooled ions
along any desired trajectory, and describe a method for determining the effect
of arbitrary shuttling schedules on the quantum state of trapped ion motion. In
addition to the general case of linear shuttling over short distances, we
introduce issues particular to the shuttling through multidimensional
junctions, which are required for the arbitrary control of the positions of
large arrays of trapped ions. This includes the transport of ions around a
corner, through a cross or T junction, and the swapping of positions of
multiple ions in a laser-cooled crystal. Where possible, we make connections to
recent experimental results in a multidimensional T junction trap, where
arbitrary 2-dimensional transport was realized.
| [
{
"version": "v1",
"created": "Fri, 16 Feb 2007 22:58:12 GMT"
},
{
"version": "v2",
"created": "Mon, 19 Feb 2007 21:27:47 GMT"
},
{
"version": "v3",
"created": "Wed, 20 Feb 2008 14:39:47 GMT"
}
] | 2008-02-20T00:00:00 | [
[
"Hucul",
"D.",
""
],
[
"Yeo",
"M.",
""
],
[
"Hensinger",
"W. K.",
""
],
[
"Rabchuk",
"J.",
""
],
[
"Olmschenk",
"S.",
""
],
[
"Monroe",
"C.",
""
]
] |
quant-ph/0702176 | Jun Chen | Jun Chen, Kim Fook Lee, and Prem Kumar | Quantum theory of degenerate $\chi^{(3)}$ two-photon state | 8 pages, 3 figures | null | null | null | quant-ph | null | We developed a quantum theory for degenerate $\chi^{(3)}$ two-photon state
generated from optical fiber, and compared the theory predictions with an
experimental result which exhibits a Hong-Ou-Mandel dip visibility of around
94%. Excellent agreement between theory and experiment has been achieved, and
we attribute the missing 6% visibility mainly to spatial mode mismatch between
signal and idler photons at the beamsplitter.
| [
{
"version": "v1",
"created": "Sat, 17 Feb 2007 00:44:32 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Chen",
"Jun",
""
],
[
"Lee",
"Kim Fook",
""
],
[
"Kumar",
"Prem",
""
]
] |
quant-ph/0702177 | Gerardo Paz Silva | Gerardo A. Paz-Silva and John H. Reina | Total correlations as fully additive entanglement monotones | 8 pages, 3 figures. Title changed, new results | J. Phys. A: Math. Theor. 42 (2009) 055306 | 10.1088/1751-8113/42/5/055306 | null | quant-ph | null | We generalize the strategy presented in Refs. [1, 2], and propose general
conditions for a measure of total correlations to be an entanglement monotone
using its pure (and mixed) convex-roof extension. In so doing, we derive
crucial theorems and propose a concrete candidate for a total correlations
measure which is a fully additive entanglement monotone.
| [
{
"version": "v1",
"created": "Sat, 17 Feb 2007 00:47:09 GMT"
},
{
"version": "v2",
"created": "Thu, 5 Apr 2007 19:01:39 GMT"
}
] | 2010-09-07T00:00:00 | [
[
"Paz-Silva",
"Gerardo A.",
""
],
[
"Reina",
"John H.",
""
]
] |
quant-ph/0702178 | Alexander K. Motovilov | Alexander K. Motovilov | Resonances of Multichannel Systems | Based on a talk presented at the UNISA-JINR Symposium "Models and
Methods in Few- and Many-Body Systems" (6-9 February 2007, Skukuza, Kruger
National Park, South Africa | Models and Methods in Few- and Many-Body Systems. Proc. of the
DST-UNISA-JINR Symposium/Ed.: S.A.Sofianos (UNISA Press, Pretoria 2007), pp.
136--150 | null | null | quant-ph math-ph math.MP nucl-th | null | We describe structure of the T-matrices, scattering matrices, and Green
functions on unphysical energy sheets in multichannel scattering problems with
binary channels and in the three-body problem. Based on the explicit
representations obtained for the values of T- and S-matrices on the unphysical
sheets, we prove that the resonances belonging to an unphysical sheet are just
those energies where the correspondingly truncated scattering matrix, taken in
the physical sheet, has eigenvalue zero. We show, in addition, that
eigenvectors of the truncated scattering matrix associated with its zero
eigenvalue are formed of the breakup amplitudes for the respective resonant
states.
| [
{
"version": "v1",
"created": "Sat, 17 Feb 2007 22:03:26 GMT"
}
] | 2007-12-06T00:00:00 | [
[
"Motovilov",
"Alexander K.",
""
]
] |
quant-ph/0702179 | Yishai Shimoni | Yishai Shimoni and Ofer Biham | Groverian Entanglement Measure of Pure Quantum States with Arbitrary
Partitions | 5 pages, 2 figures, 1 table | Phys. Rev. A. 75, 022308(2007) | null | null | quant-ph | null | The Groverian entanglement measure of pure quantum states of $n$ qubits is
generalized to the case in which the qubits are divided into any $m \le n$
parties and the entanglement between these parties is evaluated. To demonstrate
this measure we apply it to general states of three qubits and to symmetric
states with any number of qubits such as the Greenberg-Horne-Zeiliner state and
the W state.
| [
{
"version": "v1",
"created": "Sun, 18 Feb 2007 15:43:42 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Shimoni",
"Yishai",
""
],
[
"Biham",
"Ofer",
""
]
] |
quant-ph/0702180 | Jiri Tolar | P. Luft, G. Chadzitaskos, J. Tolar | Dihedral symmetry of periodic chain: quantization and coherent states | 13 pages; minor changes of the text | J. Phys. A: Math. Theor. 40 (2007), 4833-4845 | 10.1088/1751-8113/40/18/010 | null | quant-ph | null | Our previous work on quantum kinematics and coherent states over finite
configuration spaces is extended: the configuration space is, as before, the
cyclic group Z_n of arbitrary order n=2,3,..., but a larger group - the
non-Abelian dihedral group D_n - is taken as its symmetry group. The
corresponding group related coherent states are constructed and their
overcompleteness proved. Our approach based on geometric symmetry can be used
as a kinematic framework for matrix methods in quantum chemistry of ring
molecules.
| [
{
"version": "v1",
"created": "Mon, 19 Feb 2007 15:43:43 GMT"
},
{
"version": "v2",
"created": "Wed, 2 May 2007 13:38:48 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Luft",
"P.",
""
],
[
"Chadzitaskos",
"G.",
""
],
[
"Tolar",
"J.",
""
]
] |
quant-ph/0702181 | Haret Rosu | H.C. Rosu, J.L. Moran-Lopez | Stationary states in a potential well | 40 pages, 9 figures, prepared as a book chapter, last section on BICs
could be not only of historic interest | Encyclopedia of Life Support Systems, UNESCO, EOLSS Publishers,
England, 2007 | null | null | quant-ph | null | We review here in a historical context the topic of stationary states in the
quantum world, including the generalization to the primary ideas. We also
discuss the stationary states in one dimensional parabolic wells and the three
dimensional Coulomb and parabolic cases, as well as the stationary bound states
in the continuum
| [
{
"version": "v1",
"created": "Sun, 18 Feb 2007 20:36:00 GMT"
}
] | 2008-04-07T00:00:00 | [
[
"Rosu",
"H. C.",
""
],
[
"Moran-Lopez",
"J. L.",
""
]
] |
quant-ph/0702182 | Hubert de Guise | Benjamin R. Lavoie and Hubert de Guise | Su(2) intelligent states as coupled su(2) coherent states | to appear in J.Phys.A | J. Phys. A: Math. Theor. vol. 40 (2007) 2825-2837 | null | null | quant-ph | null | We show how su(2) intelligent states can be obtained by coupling su(2)
coherent states. The construction is simple and efficient, and easily leads to
a discussion of some general properties of su(2) intelligent states.
| [
{
"version": "v1",
"created": "Mon, 19 Feb 2007 03:33:56 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Lavoie",
"Benjamin R.",
""
],
[
"de Guise",
"Hubert",
""
]
] |
quant-ph/0702183 | Takeshi Koshiba | Takeshi Koshiba | Security Notions for Quantum Public-Key Cryptography | null | null | null | null | quant-ph | null | It is well known that Shor's quantum algorithm for integer factorization can
break down the RSA public-key cryptosystem, which is widely used in many
cryptographic applications. Thus, public-key cryptosystems in the quantum
computational setting are longed for cryptology. In order to define the
security notions of public-key cryptosystems, we have to model the power of the
sender, receiver, adversary and channel. While we may consider a setting where
quantum computers are available only to adversaries, we generally discuss what
are the right security notions for (quantum) public-key cryptosystems in the
quantum computational setting. Moreover, we consider the security of quantum
public-key cryptosystems known so far.
| [
{
"version": "v1",
"created": "Mon, 19 Feb 2007 06:27:37 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Koshiba",
"Takeshi",
""
]
] |
quant-ph/0702184 | Ohata Maki | Maki Ohata, Kanta Matsuura | Constructing CSS Codes with LDPC Codes for the BB84 Quantum Key
Distribution Protocol | 8 pages, 5 figures. Submitted to IEEE Trans. Info. Theory. v2,v3:
Changed Title and updated simulation results | null | null | null | quant-ph | null | In this paper, we propose how to simply construct a pair of linear codes for
the BB84 quantum key distribution protocol. This protocol allows unconditional
security in the presence of an eavesdropper, and the pair of linear codes is
used for error correction and privacy amplification. Since their high decoding
performance implies low eavesdropper's mutual information, good design of the
two codes is required. The proposed method admits using arbitrary low-density
parity-check (LDPC) codes. Therefore, it has low complexity and high
performance for hardware implementation. Simulation results show that the pair
of codes performs well against practical and various noise levels.
| [
{
"version": "v1",
"created": "Mon, 19 Feb 2007 07:14:17 GMT"
},
{
"version": "v2",
"created": "Tue, 6 Mar 2007 04:17:15 GMT"
},
{
"version": "v3",
"created": "Thu, 22 Mar 2007 17:39:40 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ohata",
"Maki",
""
],
[
"Matsuura",
"Kanta",
""
]
] |
quant-ph/0702185 | Sergei Kukhlevsky V | S. V. Kukhlevsky | Violation of Energy Conservation in Boson and Fermion Fields on
Subwavelength Nano-Scale | corrected typos | null | null | null | quant-ph hep-th math-ph math.MP physics.optics | null | The Hamiltonians describing the energy nonconservation in boson and fermion
multimode fields under quantum interference have been derived. We show that
violation of the energy conservation is accompanied by the nonconservation of
momentum, number of particles and field charge. The phenomena could be observed
in Young's double-slit subwavelength (nanometer-scale) setup.
| [
{
"version": "v1",
"created": "Mon, 19 Feb 2007 14:13:36 GMT"
},
{
"version": "v2",
"created": "Thu, 22 Feb 2007 13:23:19 GMT"
},
{
"version": "v3",
"created": "Fri, 2 Mar 2007 14:18:56 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Kukhlevsky",
"S. V.",
""
]
] |
quant-ph/0702186 | Ramazan Sever | Sameer M. Ikhdair and Ramazan Sever | Polynomial Solution of Non-Central Potentials | 18 pages | Int. J. Theor. Phys. 46, 2384(2007) | 10.1007/s10773-007-9356-8 | null | quant-ph | null | We show that the exact energy eigenvalues and eigenfunctions of the
Schrodinger equation for charged particles moving in certain class of
non-central potentials can be easily calculated analytically in a simple and
elegant manner by using Nikiforov and Uvarov (NU) method. We discuss the
generalized Coulomb and harmonic oscillator systems. We study the Hartmann
Coulomb and the ring-shaped and compound Coulomb plus Aharanov-Bohm potentials
as special cases. The results are in exact agreement with other methods.
| [
{
"version": "v1",
"created": "Mon, 19 Feb 2007 12:30:56 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Ikhdair",
"Sameer M.",
""
],
[
"Sever",
"Ramazan",
""
]
] |
quant-ph/0702187 | Joseph M. Renes | Joseph M. Renes and Jean-Christian Boileau | Privacy Amplification, Private States, and the Uncertainty Principle | null | null | 10.1103/PhysRevA.78.032335 | null | quant-ph | null | We show that three principle means of treating privacy amplification in
quantum key distribution, private state distillation, classical privacy
amplification, and via the uncertainty principle, are equivalent and
interchangeable. By adapting the security proof based on the uncertainty
principle, we construct a new protocol for private state distillation which we
prove is identical to standard classical privacy amplification. Underlying this
approach is a new characterization of private states, related to their standard
formulation by the uncertainty principle, which gives a more physical
understanding of security in quantum key distribution.
| [
{
"version": "v1",
"created": "Mon, 19 Feb 2007 21:01:19 GMT"
}
] | 2013-05-29T00:00:00 | [
[
"Renes",
"Joseph M.",
""
],
[
"Boileau",
"Jean-Christian",
""
]
] |
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