id
stringlengths 9
16
| submitter
stringlengths 1
64
⌀ | authors
stringlengths 3
62.8k
| title
stringlengths 1
382
| comments
stringlengths 1
1.15k
⌀ | journal-ref
stringlengths 1
557
⌀ | doi
stringlengths 7
153
⌀ | report-no
stringlengths 1
509
⌀ | categories
stringlengths 5
125
| license
stringclasses 9
values | abstract
stringlengths 6
6.09k
| versions
listlengths 1
187
| update_date
timestamp[s]date 2007-05-23 00:00:00
2025-04-04 00:00:00
| authors_parsed
sequencelengths 1
2.83k
|
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
quant-ph/9808052 | Mauro Fortunato | Mauro Fortunato (1 and 2), Paolo Tombesi (1), and Wolfgang P. Schleich
(2) ((1) University of Camerino, (2) University of Ulm) | Quantum-Non-Demolition Endoscopic Tomography | RevTeX, 5 pages, no figures. Talk given by M. Fortunato at the
SQuO-VII, 7th International Seminar on Quantum Optics, Raubiki (Minsk),
Belarus, May 18-20 1998. To appear in the Conference Proceedings | Opt.Spectrosc.87:518,1999 | null | null | quant-ph | null | We present a new indirect method to measure the quantum state of a single
mode of the electromagnetic field in a cavity. Our proposal combines the idea
of (endoscopic) probing and that of tomography in the sense that the signal
field is coupled via a quantum-non-demolition Hamiltonian to a meter field on
which then quantum state tomography is performed using balanced homodyne
detection. This technique provides full information about the signal state. We
also discuss the influence of the measurement of the meter on the signal field.
| [
{
"version": "v1",
"created": "Wed, 26 Aug 1998 09:40:05 GMT"
}
] | 2011-04-15T00:00:00 | [
[
"Fortunato",
"Mauro",
"",
"1 and 2"
],
[
"Tombesi",
"Paolo",
"",
"University of Camerino"
],
[
"Schleich",
"Wolfgang P.",
"",
"University of Ulm"
]
] |
quant-ph/9808053 | Bg Sidharth | B.G. Sidharth | A note on the paper, "Quarks or Leptons?" | 5 pages, TeX | Mod.Phys.Lett. A14 (1999) 387-390 | 10.1142/S0217732399000444 | null | quant-ph | null | In the context of a recent description of Fermions as Kerr-Newman type black
holes with Quantum Mechanical inputs, it is shown how the quark picture can be
recovered. The advantage is that in the process we obtain a rationale for such
features as the puzzling fractional charges of the quarks, their masses,
confinement and handedness in a unified scheme.
| [
{
"version": "v1",
"created": "Wed, 26 Aug 1998 12:05:53 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Sidharth",
"B. G.",
""
]
] |
quant-ph/9808054 | Bg Sidharth | B.G. Sidharth | Low Dimensional Electrons | 3 pages, TeX | Solid State Physics Eds.R.Mukhopadhyay et.al,Universities
Press,Hyderabad,1999,p331 | null | null | quant-ph gr-qc hep-th | null | Motivated by recent work on nano tubes indicating one dimensional quantum
effects and studies of two dimensional electron gas, we consider a recent model
of Fermions as Kerr-Newman type black holes with quantum mechanical effects.
Such an anyonic fractionally charged quasi-electron picture is deduced and
identified with quarks.
| [
{
"version": "v1",
"created": "Wed, 26 Aug 1998 12:11:03 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sidharth",
"B. G.",
""
]
] |
quant-ph/9808055 | David Vitali | David Vitali and Paolo Tombesi | Using Parity Kicks for Decoherence Control | 12 pages, 3 eps figures, final version to appear in Phys. Rev. A | Phys.Rev. A59 (1999) 4178-4186 | 10.1103/PhysRevA.59.4178 | null | quant-ph | null | We show how it is possible to suppress decoherence using tailored external
forcing acting as pulses. In the limit of infinitely frequent pulses
decoherence and dissipation are completely frozen; however, a significant
decoherence suppression is already obtained when the frequency of the pulses is
of the order of the reservoir typical frequency scale. This method could be
useful in particular to suppress the decoherence of the center-of-mass motion
in ion traps.
| [
{
"version": "v1",
"created": "Wed, 26 Aug 1998 13:11:30 GMT"
},
{
"version": "v2",
"created": "Sat, 29 Aug 1998 07:35:14 GMT"
},
{
"version": "v3",
"created": "Wed, 9 Sep 1998 14:39:57 GMT"
},
{
"version": "v4",
"created": "Wed, 30 Sep 1998 16:26:26 GMT"
},
{
"version": "v5",
"created": "Wed, 10 Mar 1999 17:35:44 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Vitali",
"David",
""
],
[
"Tombesi",
"Paolo",
""
]
] |
quant-ph/9808056 | Jonathan A. Jones | J. A. Jones and M. Mosca | Approximate quantum counting on an NMR ensemble quantum computer | 4 pages LaTeX/RevTex including 4 figures (3 LaTeX, 1 PostScript).
Submitted to Physical Review Letters | Phys.Rev.Lett.83:1050,1999 | 10.1103/PhysRevLett.83.1050 | JAJQP-98-04 | quant-ph | null | We demonstrate the implementation of a quantum algorithm for estimating the
number of matching items in a search operation using a two qubit nuclear
magnetic resonance (NMR) quantum computer.
| [
{
"version": "v1",
"created": "Wed, 26 Aug 1998 13:18:45 GMT"
}
] | 2009-01-23T00:00:00 | [
[
"Jones",
"J. A.",
""
],
[
"Mosca",
"M.",
""
]
] |
quant-ph/9808057 | Mauro Fortunato | Mauro Fortunato (1), Gil Harel (2), and G. Kurizki (2) ((1) University
of Camerino, (2) Weizmann Institute of Science) | Using Conditional Measurements to Combat Decoherence | RevTeX, 5 pages, 1 figure (three Postscript files for Fig. 1 a,b, and
c, automatically included through psfig). Talk given by M. Fortunato at the
Workshop "Macroscopic Quantum Tunneling and Coherence", Naples (Italy), June
10-13 1998. To appear in the Conference Proceedings (Journal of
Superconductivity, October 1998). See also: M. Fortunato, G. Harel, and G.
Kurizki, Optics Communications 147, 71 (1998) | J.Supercond.12:825,1999 | null | null | quant-ph | null | With the help of some remarkable examples, it is shown that conditional
measurements performed on two-level atoms just after they have interacted with
a resonant cavity field mode are able to recover the coherence of number-state
superpositions, which is lost due to dissipation.
| [
{
"version": "v1",
"created": "Wed, 26 Aug 1998 13:49:37 GMT"
}
] | 2011-04-15T00:00:00 | [
[
"Fortunato",
"Mauro",
""
],
[
"Harel",
"Gil",
""
],
[
"Kurizki",
"G.",
""
]
] |
quant-ph/9808058 | Shmuel Gurvitz | S.A. Gurvitz | Dephasing and collapse in continuous measurement of a single system | 30 pages, Revised discussion of different collapse models and their
experimental consequence | null | null | null | quant-ph cond-mat | null | We show that long standing debates on the collapse and the role of the
observer in quantum mechanics can be resolved experimentally via a
nondistructive continuous monitoring of a single quantum system. An example of
such a system, coupled with the point-contact detector is presented. The
detailed quantum mechanical analysis of the entire system (including the
detector) shows that under certain conditions the measurement collapse would
generate distinctive effects in the detector behavior, which can be
experimentally investigated.
| [
{
"version": "v1",
"created": "Wed, 26 Aug 1998 14:32:08 GMT"
},
{
"version": "v2",
"created": "Fri, 12 Mar 1999 12:26:06 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gurvitz",
"S. A.",
""
]
] |
quant-ph/9808059 | Ron S. Rubin | Nathan Salwen and Ron Rubin | Still Baking | 3 or 4 pages | null | null | null | quant-ph | null | We present here a simple proof of the non-existence of a non-periodic
invariant point for the quantum baker's map propagator presented in Rubin and
Salwen (Annals of Physics, 1998), for Planck's constant h=1/N and N a positive
integer.
| [
{
"version": "v1",
"created": "Thu, 27 Aug 1998 04:11:18 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Salwen",
"Nathan",
""
],
[
"Rubin",
"Ron",
""
]
] |
quant-ph/9808060 | Christian Grosche | Christian Grosche | On the Path Integral Treatment for an Aharonov-Bohm Field on the
Hyperbolic Plane | LaTeX 12 pp., one figure | Int.J.Theor.Phys. 38 (1999) 955-969 | null | DESY 98-112 | quant-ph | null | In this paper I discuss by means of path integrals the quantum dynamics of a
charged particle on the hyperbolic plane under the influence of an
Aharonov-Bohm gauge field. The path integral can be solved in terms of an
expansion of the homotopy classes of paths. I discuss the interference pattern
of scattering by an Aharonov-Bohm gauge field in the flat space limit, yielding
a characteristic oscillating behavior in terms of the field strength. In
addition, the cases of the isotropic Higgs-oscillator and the Kepler-Coulomb
potential on the hyperbolic plane are shortly sketched.
| [
{
"version": "v1",
"created": "Thu, 27 Aug 1998 13:17:35 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Grosche",
"Christian",
""
]
] |
quant-ph/9808061 | Phil Gossett | Phil Gossett | Quantum Carry-Save Arithmetic | 12 pages, embedded figures. Corrected typos, added clarifications,
improved result | null | null | SGI-98-5433-3b | quant-ph | null | This paper shows how to design efficient arithmetic elements out of quantum
gates using "carry-save" techniques borrowed from classical computer design.
This allows bit-parallel evaluation of all the arithmetic elements required for
Shor's algorithm, including modular arithmetic, deferring all carry propagation
until the end of the entire computation. This reduces the quantum gate delay
from O(N^3) to O(N log N) at a cost of increasing the number of qubits required
from O(N) to O(N^2).
| [
{
"version": "v1",
"created": "Thu, 27 Aug 1998 23:48:04 GMT"
},
{
"version": "v2",
"created": "Sun, 30 Aug 1998 02:25:44 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gossett",
"Phil",
""
]
] |
quant-ph/9808062 | Michael Mensky | J.Audretsch (University of Konstanz, Konstanz, Germany), M. B.Mensky
(Lebedev Institute, Moscow, Russia, and University of Konstanz, Konstanz,
Germany) | Realization scheme for continuous fuzzy measurement of energy and the
monitoring of a quantum transition | 17 pages, LaTeX, 4 figures in EPS | null | null | null | quant-ph | null | The continuous fuzzy measurement of energy of a single two-level system
driven by a resonant external field is studied. An analysis is given in the
framework of the phenomenological restricted path integral approach (RPI)
(which reduces effectively to a Schrodinger equation with a complex
Hamiltonian) as well as with reference to the microphysical details of a class
of concrete physical realizations. Within the RPI approach it is demonstrated
that for appropriately adjusted fuzziness, information about the evolution of
the state of the system can be read off from the measurement readout E(t). It
is shown furthermore how a measurement of this type may be realized by a series
of weak and short interactions of the two-level system with a quantum
mechanical meter system. After each interaction a macroscopic measuring
apparatus causes the meter to transit into one of two states. The result is
used to generate the energy readout E(t). In this way a complete agreement with
the RPI approach is demonstrated which thus obtains an operational
interpretation.
| [
{
"version": "v1",
"created": "Fri, 28 Aug 1998 12:08:17 GMT"
},
{
"version": "v2",
"created": "Sat, 26 Dec 1998 17:54:03 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Audretsch",
"J.",
"",
"University of Konstanz, Konstanz, Germany"
],
[
"Mensky",
"M. B.",
"",
"Lebedev Institute, Moscow, Russia, and University of Konstanz, Konstanz,\n Germany"
]
] |
quant-ph/9808063 | Tomohiro Ogawa | Tomohiro Ogawa, Hiroshi Nagaoka | Strong Converse to the Quantum Channel Coding Theorem | LaTeX, 11 pages, submitted to IEEE Trans. Inform. Theory | IEEE Trans.Info.Theor. 45 (1999) 2486-2489 | 10.1109/18.796386 | null | quant-ph | null | A lower bound on the probability of decoding error of quantum communication
channel is presented. The strong converse to the quantum channel coding theorem
is shown immediately from the lower bound. It is the same as Arimoto's method
exept for the difficulty due to non-commutativity.
| [
{
"version": "v1",
"created": "Fri, 28 Aug 1998 13:51:44 GMT"
},
{
"version": "v2",
"created": "Mon, 7 Sep 1998 06:21:43 GMT"
}
] | 2016-11-17T00:00:00 | [
[
"Ogawa",
"Tomohiro",
""
],
[
"Nagaoka",
"Hiroshi",
""
]
] |
quant-ph/9808064 | Paulo Americo Maia Neto | D. F. Mundarain and P. A. Maia Neto | Quantum radiation in a plane cavity with moving mirrors | 17 pages, 1 figure, published in Physical Review A | Phys.Rev. A57 (1998) 1379 | 10.1103/PhysRevA.57.1379 | null | quant-ph | null | We consider the electromagnetic vacuum field inside a perfect plane cavity
with moving mirrors, in the nonrelativistic approximation. We show that low
frequency photons are generated in pairs that satisfy simple properties
associated to the plane geometry. We calculate the photon generation rates for
each polarization as functions of the mechanical frequency by two independent
methods: on one hand from the analysis of the boundary conditions for moving
mirrors and with the aid of Green functions; and on the other hand by an
effective Hamiltonian approach. The angular and frequency spectra are discrete,
and emission rates for each allowed angular direction are obtained. We discuss
the dependence of the generation rates on the cavity length and show that the
effect is enhanced for short cavity lengths. We also compute the dissipative
force on the moving mirrors and show that it is related to the total radiated
energy as predicted by energy conservation.
| [
{
"version": "v1",
"created": "Fri, 28 Aug 1998 17:09:40 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Mundarain",
"D. F.",
""
],
[
"Neto",
"P. A. Maia",
""
]
] |
quant-ph/9808065 | Duer Wolfgang | W. D\"ur, H.- J. Briegel, J. I. Cirac, and P. Zoller | Quantum repeaters based on entanglement purification | 19 pages, 16 figures | Phys.Rev.A59:169,1999 | 10.1103/PhysRevA.59.169 | null | quant-ph | null | We study the use of entanglement purification for quantum communication over
long distances. For distances much longer than the coherence length of a
corresponding noisy quantum channel, the fidelity of transmission is usually so
low that standard purification methods are not applicable. It is however
possible to divide the channel into shorter segments that are purified
separately and then connected by the method of entanglement swapping. This
method can be much more efficient than schemes based on quantum error
correction, as it makes explicit use of two-way classical communication. An
important question is how the noise, introduced by imperfect local operations
(that constitute the protocols of purification and the entanglement swapping),
accumulates in such a compound channel, and how it can be kept below a certain
noise level. To treat this problem, we first study the applicability and the
efficiency of entanglement purification protocols in the situation of imperfect
local operations. We then present a scheme that allows entanglement
purification over arbitrary long channels and tolerates errors on the per-cent
level. It requires a polynomial overhead in time, and an overhead in local
resources that grows only logarithmically with the length of the channel.
| [
{
"version": "v1",
"created": "Mon, 31 Aug 1998 10:46:39 GMT"
}
] | 2008-12-18T00:00:00 | [
[
"Dür",
"W.",
""
],
[
"Briegel",
"H. - J.",
""
],
[
"Cirac",
"J. I.",
""
],
[
"Zoller",
"P.",
""
]
] |
quant-ph/9808066 | C. W. J. Beenakker | C.W.J. Beenakker (Leiden University) | Photon statistics of a random laser | 26 pages, including 9 figures | Diffuse Waves in Complex Media, edited by J.-P. Fouque, NATO
Science Series C531 (Kluwer, Dordrecht, 1999) | 10.1007/978-94-011-4572-5_6 | null | quant-ph cond-mat.mes-hall | null | A general relationship is presented between the statistics of thermal
radiation from a random medium and its scattering matrix S. Familiar results
for black-body radiation are recovered in the limit S to 0. The mean photocount
is proportional to the trace of 1-SS^dagger, in accordance with Kirchhoff's law
relating emissivity and absorptivity. Higher moments of the photocount
distribution are related to traces of powers of 1-SS^dagger, a generalization
of Kirchhoff's law. The theory can be applied to a random amplifying medium (or
"random laser") below the laser threshold, by evaluating the Bose-Einstein
function at a negative temperature. Anomalously large fluctuations are
predicted in the photocount upon approaching the laser threshold, as a
consequence of overlapping cavity modes with a broad distribution of spectral
widths.
| [
{
"version": "v1",
"created": "Mon, 31 Aug 1998 12:57:21 GMT"
}
] | 2013-04-08T00:00:00 | [
[
"Beenakker",
"C. W. J.",
"",
"Leiden University"
]
] |
quant-ph/9808067 | Chris Isham | C.J.Isham and J. Butterfield | A topos perspective on the Kochen-Specker theorem: II. Conceptual
Aspects, and Classical Analogues: | Small changes and corrections | Int.J.Theor.Phys. 38 (1999) 827-859 | null | Imperial/TP/97--98/71 | quant-ph gr-qc math-ph math.MP | null | In a previous paper, we have proposed assigning as the value of a physical
quantity in quantum theory, a certain kind of set (a sieve) of quantities that
are functions of the given quantity. The motivation was in part physical---such
a valuation illuminates the Kochen-Specker theorem; and in part
mathematical---the valuation arises naturally in the topos theory of
presheaves.
This paper discusses the conceptual aspects of this proposal. We also
undertake two other tasks. First, we explain how the proposed valuations could
arise much more generally than just in quantum physics; in particular, they
arise as naturally in classical physics. Second, we give another motivation for
such valuations (that applies equally to classical and quantum physics). This
arises from applying to propositions about the values of physical quantities
some general axioms governing partial truth for any kind of proposition.
| [
{
"version": "v1",
"created": "Mon, 31 Aug 1998 15:11:54 GMT"
},
{
"version": "v2",
"created": "Sun, 8 Nov 1998 16:35:40 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Isham",
"C. J.",
""
],
[
"Butterfield",
"J.",
""
]
] |
quant-ph/9809001 | Adonai S. Sant'Anna | Adonai S. Sant'Anna (Dept. of Mathematics, Federal University at
Parana) | A realistic interpretation for quantum mechanics | 11 pages, no figures, 19 references, LaTeX | null | null | null | quant-ph | null | We propose a realistic and nonlocal interpretation for quantum mechanics,
which requires new mathematical, physical and philosophical foundations for
space-time. Our theory violates Bell's inequality. We also discuss the cat
paradox.
| [
{
"version": "v1",
"created": "Tue, 1 Sep 1998 00:53:21 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sant'Anna",
"Adonai S.",
"",
"Dept. of Mathematics, Federal University at\n Parana"
]
] |
quant-ph/9809002 | Hayashi Masahito | Masahito Hayashi | Asymptotic quantum estimation theory for the displaced thermal states
family | LateX, 6 pages. It is submitted to QCM'98 proceedings | # Quantum Communication, Computing, and Measurement, Plenum
Publishing, pp.390-394 (2000). | null | null | quant-ph | null | Concerning state estimation, we will compare two cases. In one case we cannot
use the quantum correlations between samples. In the other case, we can use
them. In addition, under the later case, we will propose a method which
simultaneously measures the complex amplitude and the expected photon number
for the displaced thermal states.
| [
{
"version": "v1",
"created": "Tue, 1 Sep 1998 10:21:50 GMT"
},
{
"version": "v2",
"created": "Tue, 15 Sep 1998 09:22:07 GMT"
},
{
"version": "v3",
"created": "Wed, 28 Oct 1998 07:38:34 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Hayashi",
"Masahito",
""
]
] |
quant-ph/9809003 | Andrea Nemes Salgueiro | A. N. Salgueiro (1), M. C. Nemes (2), M. D. Sampaio (2) and A. F. R.
de Toledo Piza (1) ((1) Intituto de Fisica da Universidade de Sao Paulo
(USP); (2) Departamento de Fisica, Universidade Federal de Minas Gerais
(UFMG), Brazil) | Quasi-classical dynamics of interacting Bose condensates | this paper has been submitted to PRA | null | null | null | quant-ph | null | The dynamics of the composition of uniform Bose condensates involving two
species capable of reciprocal interconversion is treated in terms of a
collective quasi-spin model. This collective model quickly reduces to classical
form towards the thermodynamic limit. Quantum solutions are easily obtained
numerically short of this limit which give insight into the dynamically
relevant correlation processes.
| [
{
"version": "v1",
"created": "Wed, 2 Sep 1998 14:13:21 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Salgueiro",
"A. N.",
""
],
[
"Nemes",
"M. C.",
""
],
[
"Sampaio",
"M. D.",
""
],
[
"Piza",
"A. F. R. de Toledo",
""
]
] |
quant-ph/9809004 | Colin P. Williams | Amir Fijany (1) and Colin P. Williams (1) ((1) Jet Propulsion
Laboratory, California Institute of Technology) | Quantum Wavelet Transforms: Fast Algorithms and Complete Circuits | 22 pages, 10 figures | null | null | null | quant-ph | null | The quantum Fourier transform (QFT), a quantum analog of the classical
Fourier transform, has been shown to be a powerful tool in developing quantum
algorithms. However, in classical computing there is another class of unitary
transforms, the wavelet transforms, which are every bit as useful as the
Fourier transform. Wavelet transforms are used to expose the multi-scale
structure of a signal and are likely to be useful for quantum image processing
and quantum data compression. In this paper, we derive efficient, complete,
quantum circuits for two representative quantum wavelet transforms, the quantum
Haar and quantum Daubechies $D^{(4)}$ transforms. Our approach is to factor the
operators for these transforms into direct sums, direct products and dot
products of unitary matrices. In so doing, we find that permutation matrices, a
particular class of unitary matrices, play a pivotal role. Surprisingly, we
find that operations that are easy and inexpensive to implement classically are
not always easy and inexpensive to implement quantum mechanically, and vice
versa. In particular, the computational cost of performing certain permutation
matrices is ignored classically because they can be avoided explicitly.
However, quantum mechanically, these permutation operations must be performed
explicitly and hence their cost enters into the full complexity measure of the
quantum transform. We consider the particular set of permutation matrices
arising in quantum wavelet transforms and develop efficient quantum circuits
that implement them. This allows us to design efficient, complete quantum
circuits for the quantum wavelet transform.
| [
{
"version": "v1",
"created": "Wed, 2 Sep 1998 22:45:10 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Fijany",
"Amir",
""
],
[
"Williams",
"Colin P.",
""
]
] |
quant-ph/9809005 | Raj Vatsya | S. R. Vatsya | Primal structure of Quantum Mechanics - A critique and an alternative | 14 pages Latex. To be submitted to American Journal of Physics.
Quantum mechanical interpretations of various observations and their
implications, including some issues that are usually ignored, are presented
and compared here with the gauge mechanical descriptions | null | null | null | quant-ph | null | The basic premise of Quantum Mechanics, embodied in the doctrine of
wave-particle duality, assigns both, a particle and a wave structure to the
physical entities. The classical laws describing the motion of a particle and
the evolution of a wave are assumed to be correct. Gauge Mechanics treats the
discrete entities as particles, and their motion is described by an extension
of the corresponding classical laws. Quantum mechanical interpretations of
various observations and their implications, including some issues that are
usually ignored, are presented and compared here with the gauge mechanical
descriptions. The considerations are confined mainly to the conceptual
foundations and the internal consistency of these theories. Although no major
differences between their predictions have yet been noticed, some deviations
are expected, which are indicated. These cases may provide the testing grounds
for further investigations.
| [
{
"version": "v1",
"created": "Thu, 3 Sep 1998 22:11:50 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Vatsya",
"S. R.",
""
]
] |
quant-ph/9809006 | M. O. Terra Cunha | M.O. Terra Cunha | What is Surrealistic about Bohm Trajectories? | 9 pages, 4 figures, Submitted to Phys. Lett. A | null | null | null | quant-ph | null | We discuss interferometers in Bohmian quantum mechanics. It is shown that,
with the correct configuration space, Bohm trajectories in a which way
interferometer are not surrealistic, but behaves exactly as common sense
suggests. Some remarks about a way to generalize Bohmian mechanics to treat
density matrix are also made.
PACS: 03.65.Bz, 03.75.Dg
Key words: Bohm Trajectories, Which Way Interferometers, ESSW
| [
{
"version": "v1",
"created": "Thu, 3 Sep 1998 11:15:50 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Cunha",
"M. O. Terra",
""
]
] |
quant-ph/9809007 | M. Patra | M. Patra and C. W. J. Beenakker | Long-range correlation of thermal radiation | 4 pages, 3 figures | Phys.Rev. A59 (1999) 43-46 | 10.1103/PhysRevA.59.R43 | null | quant-ph cond-mat.mes-hall | null | A general theory is presented for the spatial correlations in the intensity
of the radiation emitted by a random medium in thermal equilibrium. We find
that a non-zero correlation persists over distances large compared to the
transverse coherence length of the thermal radiation. This long-range
correlation vanishes in the limit of an ideal black body. We analyze two types
of systems (a disordered waveguide and an optical cavity with chaotic
scattering) where it should be observable.
| [
{
"version": "v1",
"created": "Fri, 4 Sep 1998 12:02:05 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Patra",
"M.",
""
],
[
"Beenakker",
"C. W. J.",
""
]
] |
quant-ph/9809008 | Frank Gaitan | Frank Gaitan | Berry's Phase in the Presence of a Non-Adiabatic Environment | 21 pages, 1 Postscript figure, submitted to Phys. Rev. A | null | null | 1LPI-123 | quant-ph cond-mat | null | We consider a two-level system coupled to an environment that evolves
non-adiabatically. We present a non-perturbative method for determining the
persistence amplitude whose phase contains all the corrections to Berry's phase
produced by the non-adiabatic motion of the environment. Specifically, it
includes the effects of transitions between the two energy levels to all orders
in the non-adiabatic coupling. The problem of determining all non-adiabatic
corrections is reduced to solving an ordinary differential equation to which
numerical methods should provide solutions in a variety of situations. We apply
our method to a particular example that can be realized as a magnetic resonance
experiment, thus raising the possibility of testing our results in the lab.
| [
{
"version": "v1",
"created": "Fri, 4 Sep 1998 19:16:33 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gaitan",
"Frank",
""
]
] |
quant-ph/9809009 | Andrew T. Sornborger | A. T. Sornborger and E. D. Stewart | Higher-Order Methods for Quantum Simulations | 4 pages, 1 figure | Phys.Rev. A60 (1999) 156-1965 | null | Fermilab-Pub-98/270-A | quant-ph | null | To efficiently implement many-particle quantum simulations on quantum
computers we develop and present methods for inverting the
Campbell-Baker-Hausdorff lemma to 3rd and 4th order in the commutator. That is,
we reexpress exp{-i(H_1 + H_2 + ...)dt} as a product of factors exp(-i H_1 dt),
exp(-i H_2 dt), ... which is accurate to 3rd or 4th order in dt.
| [
{
"version": "v1",
"created": "Fri, 4 Sep 1998 19:17:01 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sornborger",
"A. T.",
""
],
[
"Stewart",
"E. D.",
""
]
] |
quant-ph/9809010 | Howard N. Barnum | H. Barnum, E. Knill, M. A. Nielsen | On Quantum Fidelities and Channel Capacities | 13 pages, uses IEEEtran.cls, rawfonts.sty, somedefs.sty. Submitted to
IEEE Transactions on Information Theory | IEEE Trans.Info.Theor. 46 (2000) 1317-1329 | 10.1109/18.850671 | null | quant-ph | null | We show the equivalence of two different notions of quantum channel capacity:
that which uses the entanglement fidelity as its criterion of success in
transmission, and that which uses the minimum fidelity of pure states in a
subspace of the input Hilbert space as its criterion. As a corollary, any
source with entropy rate less than the capacity may be transmitted with high
entanglement fidelity. We also show that a restricted class of encodings is
sufficient to transmit any quantum source which may be transmitted on a given
channel. This enables us to simplify a known upper bound for the channel
capacity. It also enables us to show that the availability of an auxiliary
classical channel from encoder to decoder does not increase the quantum
capacity.
| [
{
"version": "v1",
"created": "Fri, 4 Sep 1998 20:49:43 GMT"
}
] | 2016-11-18T00:00:00 | [
[
"Barnum",
"H.",
""
],
[
"Knill",
"E.",
""
],
[
"Nielsen",
"M. A.",
""
]
] |
quant-ph/9809011 | Wang Zhen | Zhen Wang | Measurement and Its Mathematical Scale | LaTex, 5 pages, no figure | null | null | LNU-98-09 | quant-ph | null | It is argued that every measurement is made in a certain scale. The scale in
which present measuments are made is called present scale which gives present
knowledge. Quantities at the limits to present measurement may be observables
in other scales. Cantor's series of infinites is used to describe scales of
measurement. Continuum Hypothesis and Schroedinger Cat are discussed.
| [
{
"version": "v1",
"created": "Fri, 4 Sep 1998 21:33:48 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Wang",
"Zhen",
""
]
] |
quant-ph/9809012 | Mike York | Michael J. York | Spatial Asymmetry For Particle Pairs And The Spin-Statistics Theorem | LaTeX. 29 pages originally, now 32 pages. Changes are minor
corrections and clarifications | null | null | null | quant-ph | null | We discuss the conditions under which identical particles may yet be
distinguishable and the relationship between particle permutation and exchange.
We show that we can always define permutation-symmetric state vectors. When the
particles are completely indistinguishable, then exchange is equivalent to
permutation and therefore the exchange eigenvalue for such
permutation-symmetric state vectors is always +1. Exchange asymmetry arises
when the particles are physically distinguishable, even though otherwise
identical, and can be computed from the transformations that arise when the
distinguishing features are reversed.
There is a fundamental spatial asymmetry between the relative orientations of
any two vectors in a common frame of reference that persists even in the limit
that the vectors coincide. For a pair of particles this asymmetry between their
spin quantization frames renders them distinguishable even when otherwise
identical. In the conventional construction, this distinction is not properly
accounted for. Particle exchange is then equivalent to reversing this relative
orientation --- which requires a relative rotation by 2pi on the spin
quantization frame of one particle with respect to the other, thus resulting in
the conventional exchange phase.
| [
{
"version": "v1",
"created": "Sat, 5 Sep 1998 05:52:08 GMT"
},
{
"version": "v2",
"created": "Tue, 6 Oct 1998 07:23:43 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"York",
"Michael J.",
""
]
] |
quant-ph/9809013 | Eric Cormier | Eric Cormier, Anna Sanpera, Maciej Lewenstein and Pierre Agostini | Interference effects in two-photon ATI by multiple orders high harmonics
with random or locked phases | 11 pages, 13 figures, LaTeX | null | 10.1103/PhysRevA.59.3736 | null | quant-ph | null | We numerically study 2-photon processes using a set of harmonics from a
Ti:Sapphire laser and in particular interference effects in the Above Threshold
Ionization spectra. We compare the situation where the harmonic phases are
assumed locked to the case where they have a random distribution. Suggestions
for possible experiments, using realistic parameters are discussed.
| [
{
"version": "v1",
"created": "Mon, 7 Sep 1998 08:46:53 GMT"
},
{
"version": "v2",
"created": "Mon, 28 Sep 1998 13:12:39 GMT"
},
{
"version": "v3",
"created": "Mon, 18 Jan 1999 12:56:38 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Cormier",
"Eric",
""
],
[
"Sanpera",
"Anna",
""
],
[
"Lewenstein",
"Maciej",
""
],
[
"Agostini",
"Pierre",
""
]
] |
quant-ph/9809014 | Tim Newman | T. J. Newman and R. K. P. Zia (Virginia Tech) | Three manifestations of the pulsed harmonic potential | 34 Revtex pages, with 5 attached figures | J.Phys.A31:9621-9640,1998 | 10.1088/0305-4470/31/48/002 | null | quant-ph cond-mat.stat-mech | null | We consider, in turn, three systems being acted upon by a regularly pulsed
harmonic potential (PHP). These are i) a classical particle, ii) a quantum
particle, and iii) a directed line. We contrast the mechanics of the first two
systems by parameterizing their bands of stability and periodicity. Interesting
differences due to quantum fluctuations are examined in detail. The
fluctuations of the directed line are calculated in the two cases of a binding
PHP, and an unbinding PHP. In the latter case there is a finite maximum line
length for a given potential strength.
| [
{
"version": "v1",
"created": "Mon, 7 Sep 1998 19:23:43 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Newman",
"T. J.",
"",
"Virginia Tech"
],
[
"Zia",
"R. K. P.",
"",
"Virginia Tech"
]
] |
quant-ph/9809015 | Yuri I. Ozhigov | Yuri Ozhigov | Fast quantum verification for the formulas of predicate calculus | Reference to the work quant-ph/9802040 with the similar result is
added | null | null | null | quant-ph | null | Quantum algorithm is constructed which verifies the formulas of predicate
calculus in time $O(\sqrt N)$ with bounded error probability, where $N$ is the
time required for classical algorithms. This algorithm uses the polynomial
number of simultaneous oracle queries. This is a modification of the result of
Buhrman, Cleve and Wigderson quant-ph/9802040.
| [
{
"version": "v1",
"created": "Tue, 8 Sep 1998 11:40:37 GMT"
},
{
"version": "v2",
"created": "Tue, 22 Sep 1998 09:02:03 GMT"
},
{
"version": "v3",
"created": "Wed, 23 Sep 1998 14:19:14 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ozhigov",
"Yuri",
""
]
] |
quant-ph/9809016 | Eleanor G. Rieffel | Eleanor G. Rieffel and Wolfgang Polak | An Introduction to Quantum Computing for Non-Physicists | 45 pages. To appear in ACM Computing Surveys. LATEX file. Exposition
improved throughout thanks to reviewers' comments | ACM Comput.Surveys 32:300-335,2000 | null | FXPAL-TR-98-044 | quant-ph cs.GL | null | Richard Feynman's observation that quantum mechanical effects could not be
simulated efficiently on a computer led to speculation that computation in
general could be done more efficiently if it used quantum effects. This
speculation appeared justified when Peter Shor described a polynomial time
quantum algorithm for factoring integers.
In quantum systems, the computational space increases exponentially with the
size of the system which enables exponential parallelism. This parallelism
could lead to exponentially faster quantum algorithms than possible
classically. The catch is that accessing the results, which requires
measurement, proves tricky and requires new non-traditional programming
techniques.
The aim of this paper is to guide computer scientists and other
non-physicists through the conceptual and notational barriers that separate
quantum computing from conventional computing. We introduce basic principles of
quantum mechanics to explain where the power of quantum computers comes from
and why it is difficult to harness. We describe quantum cryptography,
teleportation, and dense coding. Various approaches to harnessing the power of
quantum parallelism are explained, including Shor's algorithm, Grover's
algorithm, and Hogg's algorithms. We conclude with a discussion of quantum
error correction.
| [
{
"version": "v1",
"created": "Tue, 8 Sep 1998 19:02:58 GMT"
},
{
"version": "v2",
"created": "Wed, 19 Jan 2000 01:48:39 GMT"
}
] | 2010-01-05T00:00:00 | [
[
"Rieffel",
"Eleanor G.",
""
],
[
"Polak",
"Wolfgang",
""
]
] |
quant-ph/9809017 | Jerry Finkelstein | J. Finkelstein | Comment on "Consistency, amplitudes, and probabilities in quantum
theory" | LaTeX, 5 pages, no figures | Phys.Rev. A60 (1999) 1723-1724 | 10.1103/PhysRevA.60.1723 | SJSU/TP-98-17 | quant-ph | null | In a recent article [Phys. Rev. A 57, 1572 (1998)] Caticha has concluded that
``nonlinear variants of quantum mechanics are inconsistent.'' In this note we
identify what it is that nonlinear quantum theories have been shown to be
inconsistent with.
| [
{
"version": "v1",
"created": "Tue, 8 Sep 1998 21:57:08 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Finkelstein",
"J.",
""
]
] |
quant-ph/9809018 | Stefan Weigert | Jean-Pierre Amiet and Stefan Weigert | Reconstructing a pure state of a spin s through three Stern-Gerlach
measurements | 4 pages, revtex | J.Phys.A32:2777-2784,1999 | 10.1088/0305-4470/32/15/006 | null | quant-ph math-ph math.MP | null | Consider a spin s prepared in a pure state. It is shown that, generically,
the moduli of the (2s+1) spin components along three directions in space
determine the state unambiguously. These probabilities are accessible
experimentally by means of a standard Stern-Gerlach apparatus. To reconstruct a
pure spin state is therefore possible on the basis of 3(2s+1) measured
intensities.
| [
{
"version": "v1",
"created": "Wed, 9 Sep 1998 13:17:08 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Amiet",
"Jean-Pierre",
""
],
[
"Weigert",
"Stefan",
""
]
] |
quant-ph/9809019 | Richard L. Hall | Richard L. Hall | An Inversion Inequality for Potentials in Quantum Mechanics | 7 pages (plain Tex), 2 figures (ps) | J.Math.Phys. 40 (1999) 2254-2258 | 10.1063/1.532862 | CUQM-73 | quant-ph math-ph math.MP | null | We suppose: (1) that the ground-state eigenvalue E = F(v) of the Schroedinger
Hamiltonian H = -Delta + vf(x) in one dimension is known for all values of the
coupling v > 0; and (2) that the potential shape can be expressed in the form
f(x) = g(x^2), where g is monotone increasing and convex. The inversion
inequality f(x) <= fbar(1/(4x^2)) is established, in which the `kinetic
potential' fbar(s) is related to the energy function F(v) by the
transformation: fbar(s) = F'(v), s = F(v) - vF'(v) As an example f is
approximately reconstructed from the energy function F for the potential f(x) =
x^2 + 1/(1+x^2).
| [
{
"version": "v1",
"created": "Wed, 9 Sep 1998 13:36:09 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Hall",
"Richard L.",
""
]
] |
quant-ph/9809020 | Mariano A. del Olmo | Jose A. Gonzalez and Mariano A. del Olmo | Coherent states on the circle | AMS-TeX file, 20 pages, 4 PostScript figures. To be published in J.
Phys. A | J.Phys.A31:8841-8857,1998 | 10.1088/0305-4470/31/44/012 | null | quant-ph | null | A careful study of the physical properties of a family of coherent states on
the circle, introduced some years ago by de Bi\`evre and Gonz\'alez in [DG 92],
is carried out. They were obtained from the Weyl-Heisenberg coherent states in
$L^2(\R)$ by means of the Weil-Brezin-Zak transformation, they are labeled by
the points of the cylinder $S^1 \times \R$, and they provide a realization of
$L^2(S^1)$ by entire functions (similar to the well-known Fock-Bargmann
construction). In particular, we compute the expectation values of the position
and momentum operators on the circle and we discuss the Heisenberg uncertainty
relation.
| [
{
"version": "v1",
"created": "Wed, 9 Sep 1998 19:18:44 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Gonzalez",
"Jose A.",
""
],
[
"del Olmo",
"Mariano A.",
""
]
] |
quant-ph/9809021 | Haret Rosu | H.C. Rosu | Strictly isospectral SUSY potentials and the Riccati superposition
principle | 4 LaTex pages | Nuovo Cim. B114 (1999) 723-726 | null | null | quant-ph math-ph math.MP | null | The connection of unbroken SUSY quantum mechanics in its strictly isospectral
form with the nonlinear Riccati superposition principle is pointed out
| [
{
"version": "v1",
"created": "Wed, 9 Sep 1998 22:55:20 GMT"
},
{
"version": "v2",
"created": "Wed, 7 Apr 1999 22:58:59 GMT"
},
{
"version": "v3",
"created": "Mon, 2 Aug 1999 18:55:30 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Rosu",
"H. C.",
""
]
] |
quant-ph/9809022 | Alexander S. Holevo | Alexander S. Holevo | Sending Quantum Information with Gaussian States | 11 pages, Latex, 2 eps figures. To appear in Proceedings of the 4th
International Conference on Quantum Communication, Measurement and Computing,
Evanston, August 22-27, 1998 | null | null | null | quant-ph | null | Quantum information characteristics, such as quantum mutual information,
loss, noise and coherent information are explicitly calculated for Bosonic
attenuation/amplification channel with input Gaussian state. The coherent
information is shown to be negative for the values of the attenuation
coefficient $k<1/\sqrt{2}$.
| [
{
"version": "v1",
"created": "Thu, 10 Sep 1998 07:51:27 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Holevo",
"Alexander S.",
""
]
] |
quant-ph/9809023 | Alexander S. Holevo | Alexander S. Holevo | Coding Theorems for Quantum Channels | 41 pages, Latex, eps figure. Extended version of report appeared in
"Tamagawa University Research Review", no. 4, 1998 | Russian Math. Surveys, vol.53, no.6 (1998), 1295-1331 | 10.1070/RM1998v053n06ABEH000091 | null | quant-ph | null | The more than thirty years old issue of the (classical) information capacity
of quantum communication channels was dramatically clarified during the last
years, when a number of direct quantum coding theorems was discovered. The
present paper gives a self contained treatment of the subject, following as
much in parallel as possible with classical information theory and, on the
other side, stressing profound differences of the quantum case. An emphasis is
made on recent results, such as general quantum coding theorems including cases
of infinite (possibly continuous) alphabets and constrained inputs, reliability
function for pure state channels and quantum Gaussian channel. Several still
unsolved problems are briefly outlined.
| [
{
"version": "v1",
"created": "Thu, 10 Sep 1998 07:52:30 GMT"
}
] | 2017-08-17T00:00:00 | [
[
"Holevo",
"Alexander S.",
""
]
] |
quant-ph/9809024 | Hendrych | Miloslav Dusek, Ondrej Haderka, Martin Hendrych, Robert Myska | Quantum identification system | RevTeX, 4 postscript figures, 9 pages, submitted to Physical Review A | null | 10.1103/PhysRevA.60.149 | null | quant-ph | null | A secure quantum identification system combining a classical identification
procedure and quantum key distribution is proposed. Each identification
sequence is always used just once and new sequences are ``refuelled'' from a
shared provably secret key transferred through the quantum channel. Two
identification protocols are devised. The first protocol can be applied when
legitimate users have an unjammable public channel at their disposal. The
deception probability is derived for the case of a noisy quantum channel. The
second protocol employs unconditionally secure authentication of information
sent over the public channel, and thus it can be applied even in the case when
an adversary is allowed to modify public communications. An experimental
realization of a quantum identification system is described.
| [
{
"version": "v1",
"created": "Thu, 10 Sep 1998 10:07:58 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Dusek",
"Miloslav",
""
],
[
"Haderka",
"Ondrej",
""
],
[
"Hendrych",
"Martin",
""
],
[
"Myska",
"Robert",
""
]
] |
quant-ph/9809025 | Wolfgang Tittel | W. Tittel, J. Brendel, N. Gisin, and H. Zbinden | Long-distance Bell-type tests using energy-time entangled photons | 22 pages including 7 figures and 5 tables | null | 10.1103/PhysRevA.59.4150 | null | quant-ph | null | Long-distance Bell-type experiments are presented. The different experimental
challenges and their solutions in order to maintain the strong quantum
correlations between energy-time entangled photons over more than 10 km are
reported and the results analyzed from the point of view of tests of
fundamental physics as well as from the more applied side of quantum
communication, specially quantum key distribution. Tests using more than one
analyzer on each side are also presented.
| [
{
"version": "v1",
"created": "Thu, 10 Sep 1998 11:14:17 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Tittel",
"W.",
""
],
[
"Brendel",
"J.",
""
],
[
"Gisin",
"N.",
""
],
[
"Zbinden",
"H.",
""
]
] |
quant-ph/9809026 | D. Trifonov | D.A. Trifonov and S.G. Donev (Institute for Nuclear Research, Sofia) | Characteristic uncertainty relations | 8 pages, LaTex, no figures. To appear in J. Phys. A | J.Phys.A31:8041-8047,1998 | 10.1088/0305-4470/31/39/016 | INRNE-TH-98/2 | quant-ph hep-th | null | New uncertainty relations for n observables are established. The relations
take the invariant form of inequalities between the characteristic coefficients
of order r, r = 1,2,...,n, of the uncertainty matrix and the matrix of mean
commutators of the observables.
It is shown that the second and the third order characteristic inequalities
for the three generators of SU(1,1) and SU(2) are minimized in the
corresponding group-related coherent states with maximal symmetry.
| [
{
"version": "v1",
"created": "Thu, 10 Sep 1998 13:16:52 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Trifonov",
"D. A.",
"",
"Institute for Nuclear Research, Sofia"
],
[
"Donev",
"S. G.",
"",
"Institute for Nuclear Research, Sofia"
]
] |
quant-ph/9809027 | Christian Korff | C. Korff, G. Lang, R. Schrader | Two-particle scattering theory for anyons | 42 pages of RevTex and 5 figures (included) | J.Math.Phys. 40 (1999) 1831-1869 | 10.1063/1.532837 | null | quant-ph cond-mat.mes-hall hep-th math-ph math.MP | null | We consider potential scattering theory of a nonrelativistic quantum
mechanical 2-particle system in R^2 with anyon statistics. Sufficient
conditions are given which guarantee the existence of wave operators and the
unitarity of the S-matrix. As examples the rotationally invariant potential
well and the delta-function potential are discussed in detail. In case of a
general rotationally invariant potential the angular momentum decomposition
leads to a theory of Jost functions. The anyon statistics parameter gives rise
to an interpolation for angular momenta analogous to the Regge trajectories for
complex angular momenta. Levinson's theorem is adapted to the present context.
In particular we find that in case of a zero energy resonance the statistics
parameter can be determined from the scattering phase.
| [
{
"version": "v1",
"created": "Thu, 10 Sep 1998 14:41:39 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Korff",
"C.",
""
],
[
"Lang",
"G.",
""
],
[
"Schrader",
"R.",
""
]
] |
quant-ph/9809028 | Wayne M. Itano | D. J. Wineland, C. Monroe, W. M. Itano, D. Kielpinski, B. E. King, C.
J. Myatt, Q. A. Turchette, and C. S. Wood | Quantum Computation, Spectroscopy of Trapped Ions, and Schrodinger's Cat | 6 pages, no figures. To appear in Proc. 6th Int. Symp. on Foundations
of Quantum Mechanics in the Light of New Technology, K. Fujikawa and Y. A.
Ono, eds. (Elsevier Science press) | null | null | null | quant-ph | null | We summarize efforts at NIST to implement quantum computation using trapped
ions, based on a scheme proposed by J.I. Cirac and P. Zoller (Innsbruck
University). The use of quantum logic to create entangled states, which can
maximize the quantum-limited signal-to-noise ratio in spectroscopy, is
discussed.
| [
{
"version": "v1",
"created": "Thu, 10 Sep 1998 14:06:50 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Wineland",
"D. J.",
""
],
[
"Monroe",
"C.",
""
],
[
"Itano",
"W. M.",
""
],
[
"Kielpinski",
"D.",
""
],
[
"King",
"B. E.",
""
],
[
"Myatt",
"C. J.",
""
],
[
"Turchette",
"Q. A.",
""
],
[
"Wood",
"C. S.",
""
]
] |
quant-ph/9809029 | Lov K. Grover | Lov K. Grover (Bell Labs, Murray Hill, NJ) | How fast can a quantum computer search? | Postscript, 7 pages. This proof tries to give a simple argument why
the search algorithm is optimal (This paper was originally put out on
quant-ph on September 9, 1998, the present version has several important
improvements) | null | null | null | quant-ph | null | This paper gives a simple proof of why a quantum computer, despite being in
all possible states simultaneously, needs at least 0.707 sqrt(N) queries to
retrieve a desired item from an unsorted list of items. The proof is refined to
show that a quantum computer would need at least 0.785 sqrt(N) queries. The
quantum search algorithm needs precisely this many queries.
| [
{
"version": "v1",
"created": "Thu, 10 Sep 1998 17:43:29 GMT"
},
{
"version": "v2",
"created": "Wed, 23 Sep 1998 16:41:53 GMT"
},
{
"version": "v3",
"created": "Tue, 13 Apr 1999 21:30:58 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Grover",
"Lov K.",
"",
"Bell Labs, Murray Hill, NJ"
]
] |
quant-ph/9809030 | Gerhard Hegerfeldt | Gerhard C. Hegerfeldt | Instantaneous Spreading and Einstein Causality in Quantum Theory | Talk given at the workshop Superluminal (?) Velocities, Cologne, June
6-10, 1998. To appear in Annalen der Physik | Annalen Phys.7:716-725,1998 | 10.1002/(SICI)1521-3889(199812)7:7/8<716::AID-ANDP716>3.0.CO;2-T | null | quant-ph | null | In nonrelativistic quantum mechanics the wave-function of a free particle
which initially is in a finite volume immediately spreads to infinity. In a
nonrelativistic theory this is of no concern, but we show that the same
instantaneous spreading can occur in relativistic quantum theory and that
transition probabilities in widely separated systems may instantaneously become
nonzero. We discuss how this affects Einstein causality.
| [
{
"version": "v1",
"created": "Fri, 11 Sep 1998 08:21:59 GMT"
}
] | 2016-04-20T00:00:00 | [
[
"Hegerfeldt",
"Gerhard C.",
""
]
] |
quant-ph/9809031 | Gerhard Hegerfeldt | Gerhard C. Hegerfeldt and Thorsten K\"ohler | Few-body approach to diffraction of small helium clusters by
nanostructures | Invited talk at the 16TH EUROPEAN CONFERENCE ON FEW-BODY PROBLEMS IN
PHYSICS, Autrans, June 1-6, 1998. To appear in Few-Body Systems Suppl | Few Body Syst.Suppl.10:263-272,1999 | null | null | quant-ph | null | We use few-body methods to investigate the diffraction of weakly bound
systems by a transmission grating. For helium dimers, He$_2$, we obtain
explicit expressions for the transition amplitude in the elastic channel.
| [
{
"version": "v1",
"created": "Fri, 11 Sep 1998 08:22:47 GMT"
}
] | 2011-04-15T00:00:00 | [
[
"Hegerfeldt",
"Gerhard C.",
""
],
[
"Köhler",
"Thorsten",
""
]
] |
quant-ph/9809032 | Bg Sidharth | B.G. Sidharth | Planck Scale to Hubble Scale | 12 pages, TeX | null | null | null | quant-ph gr-qc hep-th | null | Within the context of the usual semi classical investigation of Planck scale
Schwarzchild Black Holes, as in Quantum Gravity, and later attempts at a full
Quantum Mechanical description in terms of a Kerr-Newman metric including the
spinorial behaviour, we attempt to present a formulation that extends from the
Planck scale to the Hubble scale. In the process the so called large number
coincidences as also the hitherto inexplicable relations between the pion mass
and the Hubble Constant, pointed out by Weinberg, turn out to be natural
consequences in a consistent description.
| [
{
"version": "v1",
"created": "Fri, 11 Sep 1998 11:27:02 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sidharth",
"B. G.",
""
]
] |
quant-ph/9809033 | Michael Manthey | Michael Manthey | A Combinatorial Bit Bang Leading to Quaternions | 23 pages, 4 figures | Acta Polytechnica Scandinavica, No. 91 (1998). Farre, G.L. and
Oksala, T. (eds.): Emergence, Complexity, Hierarchy, Organization - Selected
and edited papers from the ECHO III conference. Finnish Academy of
Technology. ISBN 952-5148-59-9, ISSN 1238-9803 | null | null | quant-ph | null | This paper describes in detail how (discrete) quaternions - ie. the abstract
structure of 3-D space - emerge from, first, the Void, and thence from
primitive combinatorial structures, using only the exclusion and co-occurrence
of otherwise unspecified events. We show how this computational view
supplements and provides an interpretation for the mathematical structures, and
derive quark structure. The build-up is emergently hierarchical, compatible
with both quantum mechanics and relativity, and can be extended upwards to the
macroscopic. The mathematics is that of Clifford algebras emplaced in the
homology-cohomology structure pioneered by Kron. Interestingly, the ideas
presented here were originally developed by the author to resolve fundamental
limitations of existing AI paradigms. As such, the approach can be used for
learning, planning, vision, NLP, pattern recognition; and as well, for
modelling, simulation, and implementation of complex systems, eg. biological.
| [
{
"version": "v1",
"created": "Fri, 11 Sep 1998 13:16:47 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Manthey",
"Michael",
""
]
] |
quant-ph/9809034 | Wolfgang Tittel | J. Brendel, N. Gisin, W. Tittel, and H. Zbinden | Pulsed energy-time entangled twin-photon source for quantum
communication | 8 pages, 4 figures | Phys.Rev.Lett.82:2594-2597,1999 | 10.1103/PhysRevLett.82.2594 | null | quant-ph | null | A pulsed source of energy-time entangled photon pairs pumped by a standard
laser diode is proposed and demonstrated. The basic states can be distinguished
by their time of arrival. This greatly simplifies the realization of 2-photon
quantum cryptography, Bell state analyzers, quantum teleportation, dense
coding, entanglement swapping, GHZ-states sources, etc. Moreover the
entanglement is well protected during photon propagation in telecom optical
fibers, opening the door to few-photon applications of quantum communication
over long distances.
| [
{
"version": "v1",
"created": "Fri, 11 Sep 1998 16:06:35 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Brendel",
"J.",
""
],
[
"Gisin",
"N.",
""
],
[
"Tittel",
"W.",
""
],
[
"Zbinden",
"H.",
""
]
] |
quant-ph/9809035 | Hiroki Saito | Hiroki Saito and Masahito Ueda | Number-phase-squeezed few-photon state generated from squeezed atoms | 17 pages, RevTex, 14 figures, using epsf.sty, title is changed,
discussion about dissipation is added, accepted for publication in Physical
Review A | Phys.Rev. A59 (1999) 3959 | 10.1103/PhysRevA.59.3959 | null | quant-ph | null | This paper develops a method of manipulating the squeezed atom state to
generate a few-photon state whose phase or photon-number fluctuations are
prescribed at our disposal. The squeezed atom state is a collective atomic
state whose quantum fluctuations in population difference or collective dipole
are smaller than those of the coherent atom state. It is shown that the
squeezed atom state can be generated by the interaction of atoms with a
coherent state of the electromagnetic field, and that it can be used as a
tunable source of squeezed radiation. A variety of squeezed states, including
the photon-number squeezed state and the phase squeezed state, can be produced
by manipulating the atomic state. This is owing to the fact that
quantum-statistical information of the atomic state is faithfully transferred
to that of the photon state. Possible experimental situations to implement our
theory are discussed.
| [
{
"version": "v1",
"created": "Sun, 13 Sep 1998 12:54:51 GMT"
},
{
"version": "v2",
"created": "Mon, 21 Sep 1998 10:36:14 GMT"
},
{
"version": "v3",
"created": "Mon, 11 Jan 1999 09:36:08 GMT"
},
{
"version": "v4",
"created": "Tue, 12 Jan 1999 09:26:51 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Saito",
"Hiroki",
""
],
[
"Ueda",
"Masahito",
""
]
] |
quant-ph/9809036 | Durmus Ali Demir | D. A. Demir | Real-time tunneling | 14 pages, 1 figure, typos corrected | null | null | null | quant-ph | null | Starting with the equivalence of the rest energy of a particle to an amount
of the radiant energy characterized by a frequency, in addition to the usual
relativistic transformation rules leading to the wave-particle duality, we
investigate the case in which this frequency is an internal propery of the
particle. This kind of interpretation of the frequency is shown to be relevant
to the tunneling effect. The investigations in this direction yield (1) a
purely real time everywhere, (2) an anti-hermitian momentum operator, (3) a
corpuscular structure for the particle, and (4) all of the known theoretical
predictions about the tunneling effect.
| [
{
"version": "v1",
"created": "Sun, 13 Sep 1998 15:27:51 GMT"
},
{
"version": "v2",
"created": "Sat, 30 Jan 1999 22:04:57 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Demir",
"D. A.",
""
]
] |
quant-ph/9809037 | Paul T. Cochrane | P. T. Cochrane, G. J. Milburn and W. J. Munro | Macroscopically distinct quantum superposition states as a bosonic code
for amplitude damping | 4 pages, 2 postscript figures, LaTeX2e, RevTeX, minor changes, 1
reference added | Phys.Rev. A59 (1999) 2631 | 10.1103/PhysRevA.59.2631 | null | quant-ph | null | We show how macroscopically distinct quantum superposition states
(Schroedinger cat states) may be used as logical qubit encodings for the
correction of spontaneous emission errors. Spontaneous emission causes a bit
flip error which is easily corrected by a standard error correction circuit.
The method works arbitrarily well as the distance between the amplitudes of the
superposed coherent states increases.
| [
{
"version": "v1",
"created": "Mon, 14 Sep 1998 02:12:53 GMT"
},
{
"version": "v2",
"created": "Mon, 23 Nov 1998 06:36:42 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Cochrane",
"P. T.",
""
],
[
"Milburn",
"G. J.",
""
],
[
"Munro",
"W. J.",
""
]
] |
quant-ph/9809038 | Masanao Ozawa | Masanao Ozawa (Nagoya University) | Quantum Turing Machines: Local Transition, Preparation, Measurement, and
Halting | 8 pages, LaTeX, invited talk at 4th Int'l Conf. on Quantum
Communication, Measurement and Computing (Evanston, August 22-27, 1998) | in Quantum Communication, Computing, and Measurement 2, edited by
P. Kumer et. al. (Kluwer, New York, 2000) pp. 241-248. | null | null | quant-ph | null | Foundations of the theory of quantum Turing machines are investigated. The
protocol for the preparation and the measurement of quantum Turing machines is
discussed. The local transition functions are characterized for fully general
quantum Turing machines. A new halting protocol is proposed without augmenting
the halting qubit and is shown to work without spoiling the computation.
| [
{
"version": "v1",
"created": "Mon, 14 Sep 1998 17:56:43 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ozawa",
"Masanao",
"",
"Nagoya University"
]
] |
quant-ph/9809039 | Dominic Mayers | Dominic Mayers (Princeton), Andrew Yao (Princeton) | Quantum Cryptography with Imperfect Apparatus | 7 pages (To appear in FOCS 98) | null | null | null | quant-ph | null | Quantum key distribution, first proposed by Bennett and Brassard, provides a
possible key distribution scheme whose security depends only on the quantum
laws of physics. So far the protocol has been proved secure even under channel
noise and detector faults of the receiver, but is vulnerable if the photon
source used is imperfect. In this paper we propose and give a concrete design
for a new concept, {\it self-checking source}, which requires the manufacturer
of the photon source to provide certain tests; these tests are designed such
that, if passed, the source is guaranteed to be adequate for the security of
the quantum key distribution protocol, even though the testing devices may not
be built to the original specification. The main mathematical result is a
structural theorem which states that, for any state in a Hilbert space, if
certain EPR-type equations are satisfied, the state must be essentially the
orthogonal sum of EPR pairs.
| [
{
"version": "v1",
"created": "Tue, 15 Sep 1998 01:51:47 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Mayers",
"Dominic",
"",
"Princeton"
],
[
"Yao",
"Andrew",
"",
"Princeton"
]
] |
quant-ph/9809040 | Farhan Saif | Farhan Saif, Iwo Bialynicki-Birula, Mauro Fortunato and Wolfgang P.
Schleich | The Fermi accelerator in atom optics | 5 pages, 5 figures | null | 10.1103/PhysRevA.58.4779 | null | quant-ph | null | We study the classical and quantum dynamics of a Fermi accelerator realized
by an atom bouncing off a modulated atomic mirror. We find that in a window of
the modulation amplitude dynamical localization occurs in both position and
momentum. A recent experiment [A. Steane, P. Szriftgiser, P. Desbiolles, and J.
Dalibard, Phys. Rev. Lett. {\bf 74}, 4972 (1995)] shows that this system can be
implemented experimentally.
| [
{
"version": "v1",
"created": "Tue, 15 Sep 1998 15:04:29 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Saif",
"Farhan",
""
],
[
"Bialynicki-Birula",
"Iwo",
""
],
[
"Fortunato",
"Mauro",
""
],
[
"Schleich",
"Wolfgang P.",
""
]
] |
quant-ph/9809041 | Jan Budczies | H.M. Krenzlin, J. Budczies, and K.W. Kehr | Wave packet tunneling | 6 pages, 3 figures | Annalen Phys.7:732-736,1998 | 10.1002/(SICI)1521-3889(199812)7:7/8<732::AID-ANDP732>3.0.CO;2-0 | null | quant-ph | null | The tunneling of Gaussian wave packets has been investigated by numerically
solving the one-dimensional Schr\"odinger equation. The shape of wave packets
interacting with a square barrier has been monitored for various values of the
barrier width, height and initial width of the wave packet. Compared to the
case of free propagation, the maximum of a tunneled wave packet exhibits a
shift, which can be interpreted as an enhanced velocity during tunneling.
| [
{
"version": "v1",
"created": "Tue, 15 Sep 1998 15:26:50 GMT"
}
] | 2017-09-27T00:00:00 | [
[
"Krenzlin",
"H. M.",
""
],
[
"Budczies",
"J.",
""
],
[
"Kehr",
"K. W.",
""
]
] |
quant-ph/9809042 | Paul Slater | Paul B. Slater (University of California) | Sensitivity of estimates of the volume of the set of separable states to
the choice of "uniform" distributions | This paper has been withdrawn for two reasons: (1) it has been
superseded by "A Priori Probabilities of Quantum Disentanglements"
(quant-ph/9810026); and (2) due to a programming error, all the random
numbers generated were drawn from [0,1], while certain of them should have
been taken from [0,2 pi] | null | null | null | quant-ph | null | This paper has been withdrawn for the reasons mentioned in the Comments.
| [
{
"version": "v1",
"created": "Tue, 15 Sep 1998 20:54:14 GMT"
},
{
"version": "v2",
"created": "Wed, 16 Sep 1998 17:22:31 GMT"
},
{
"version": "v3",
"created": "Fri, 9 Oct 1998 15:41:16 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Slater",
"Paul B.",
"",
"University of California"
]
] |
quant-ph/9809043 | Geza Giedke | G. Giedke, H. Briegel, J.I. Cirac, P. Zoller | Lower Bounds for Attainable Fidelity in Entanglement Purification | 11 pages | Phys.Rev. A59 (1999) 2641-2648 | 10.1103/PhysRevA.59.2641 | null | quant-ph | null | We derive lower bounds for the attainable fidelity of standard entanglement
purification protocols when local operations and measurements are subjected to
errors. We introduce an error parameter which measures the distance between the
ideal completely positive map describing a purification step and the one in the
presence of errors. We derive non--linear maps for a lower bound of the
fidelity at each purification step in terms of this parameter.
| [
{
"version": "v1",
"created": "Wed, 16 Sep 1998 13:29:39 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Giedke",
"G.",
""
],
[
"Briegel",
"H.",
""
],
[
"Cirac",
"J. I.",
""
],
[
"Zoller",
"P.",
""
]
] |
quant-ph/9809044 | Wen-Fa Lu | Wen-Fa Lu | Thermalized Displaced and Squeezed Number States in Coordinate
Representation | 12 pages, no figures, Revtex. v3: substantially revised | J.Phys.A32:5037-5051,1999 | 10.1088/0305-4470/32/27/305 | SJTU-DAP-LU-9901 | quant-ph | null | Within the framework of thermofield dynamics, the wavefunctions of the
thermalized displaced number and squeezed number states are given in the
coordinate representation. Furthermore, the time evolution of these
wavefunctions is considered by introducing a thermal coordinate representation,
and we also calculate the corresponding probability densities, average values
and variances of position coordinate, which are consistent with results in the
literature.
| [
{
"version": "v1",
"created": "Wed, 16 Sep 1998 15:04:28 GMT"
},
{
"version": "v2",
"created": "Thu, 7 Jan 1999 13:55:12 GMT"
},
{
"version": "v3",
"created": "Mon, 22 Mar 1999 03:08:08 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Lu",
"Wen-Fa",
""
]
] |
quant-ph/9809045 | Timothy F. Havel | D. G. Cory, A. E. Dunlop, T. F. Havel, S. S. Somaroo, W. Zhang | The effective Hamiltonian of the Pound-Overhauser controlled-NOT gate | LaTeX2e (iopart.cls), 18 pages, 5 figures, submitted J. Phys. A | Concepts Magn.Reson.Part A 23:49-62,2004 | null | null | quant-ph math-ph math.MP | null | In NMR-based quantum computing, it is known that the controlled-NOT gate can
be implemented by applying a low-power, monochromatic radio-frequency field to
one peak of a doublet in a weakly-coupled two-spin system. This is known in NMR
spectroscopy as Pound-Overhauser double resonance. The ``transition''
Hamiltonian that has been associated with this procedure is however only an
approximation, which ignores off-resonance effects and does not correctly
predict the associated phase factors. In this paper, the exact effective
Hamiltonian for evolution of the spins' state in a rotating frame is derived,
both under irradiation of a single peak (on-transition) as well as between the
peaks of the doublet (on-resonance). The accuracy of these effective
Hamiltonians is validated by comparing the observable product operator
components of the density matrix obtained by simulation to those obtained by
fitting the corresponding experiments. It is further shown how both the
on-transition and on-resonance fields can be used to implement the
controlled-NOT gate exactly up to conditional phases, and analytic expressions
for these phases are derived. In Appendices, the on-resonance Hamiltonian is
analytically diagonalized, and proofs are given that, in the weak-coupling
approximation, off-resonance effects can be neglected whenever the
radio-frequency field power is small compared to the difference in resonance
frequencies of the two spins.
| [
{
"version": "v1",
"created": "Wed, 16 Sep 1998 16:41:10 GMT"
}
] | 2010-04-23T00:00:00 | [
[
"Cory",
"D. G.",
""
],
[
"Dunlop",
"A. E.",
""
],
[
"Havel",
"T. F.",
""
],
[
"Somaroo",
"S. S.",
""
],
[
"Zhang",
"W.",
""
]
] |
quant-ph/9809046 | null | G. K\"albermann (Cyclotron Institute, Texas A&M University College
Station, TX, USA) | Coherent polychotomous waves from an attractive well | Latex, 8 eps figures | null | 10.1103/PhysRevA.60.2573 | null | quant-ph nucl-th | null | A novel effect of a wave packet scattering off an attractive one- dimensional
well is found numerically and analytically. For a wave packet narrower than the
width of the well, the scattering proceeds through a quasi-bound state of
almost zero energy. The wave reflected from the well is a polychotomous
(multiple peak) monochromatic and coherent train. The transmitted wave is a
spreading smooth wave packet. The effect is strong for low average speeds of
the packet, and it disappears for wide packets.
| [
{
"version": "v1",
"created": "Wed, 16 Sep 1998 16:31:19 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Kälbermann",
"G.",
"",
"Cyclotron Institute, Texas A&M University College\n Station, TX, USA"
]
] |
quant-ph/9809047 | Hans-Peter Thienel | H.-P. Thienel | Quantum mechanics of an electron in a homogeneous magnetic field and a
singular magnetic flux tube | 23 pages, LaTeX, minor changes | Annals Phys. 280 (2000) 140-162 | 10.1006/aphy.1999.5985 | Si-98-9 | quant-ph cond-mat.mes-hall hep-th math-ph math.MP | null | The eigenvalue problem of the Hamiltonian of an electron confined to a plane
and subjected to a perpendicular time-independent magnetic field which is the
sum of a homogeneous field and an additional field contributed by a singular
flux tube, i.e. of zero width, is investigated. Since both a direct approach
based on distribution-valued operators and a limit process starting from a
non-singular flux tube, i.e. of finite size, fail, an alternative method is
applied leading to consistent results. An essential feature is quantum
mechanical supersymmetry at g=2 which imposes, by proper representation, the
correct choice of "boundary conditions". The corresponding representation of
the Hilbert space in coordinate space differs from the usual space of
square-integrable 2-spinors, entailing other unusual properties. The analysis
is extended to $g\ne 2$ so that supersymmetry is explicitly broken. Finally,
the singular Aharonov-Bohm system with the same amount of singular flux is
analysed by making use of the fact that the Hilbert space must be the same.
| [
{
"version": "v1",
"created": "Wed, 16 Sep 1998 18:45:31 GMT"
},
{
"version": "v2",
"created": "Thu, 1 Jun 2000 10:43:49 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Thienel",
"H. -P.",
""
]
] |
quant-ph/9809048 | Masanao Ozawa | Masanao Ozawa (Nagoya University) | Measurability and Computability | 8 pages, RevTeX | null | null | null | quant-ph | null | The conceptual relation between the measurability of quantum mechanical
observables and the computability of numerical functions is re-examined. A new
formulation is given for the notion of measurability with finite precision in
order to reconcile the conflict alleged by M. A. Nielsen [Phys. Rev. Lett. 79,
2915 (1997)] that the measurability of a certain observable contradicts the
Church-Turing thesis. It is argued that any function computable by a quantum
algorithm is a recursive function obeying the Church-Turing thesis, whereas any
observable can be measured in principle.
| [
{
"version": "v1",
"created": "Wed, 16 Sep 1998 20:11:45 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ozawa",
"Masanao",
"",
"Nagoya University"
]
] |
quant-ph/9809049 | S. Wallentowitz | S. Wallentowitz, W. Vogel, and P.L. Knight | High-order nonlinearities in the motion of a trapped atom | 8 pages, 3 figures (to be published in Phys. Rev. A) | null | 10.1103/PhysRevA.59.531 | null | quant-ph | null | We study the counterpart to the multi-photon down conversion in the quantised
motion of a trapped atom. The Lamb-Dicke approximation leads to a divergence of
the mean motional excitation in a finite interaction time for k-quantum down
conversions with k>=3, analogous to the situation in the parametric
approximation of nonlinear optics. We show that, in contrast to the Lamb-Dicke
approximation, the correct treatment of the overlap of the atomic
center-of-mass wave function and the driving laser waves leads to a proper
dynamics without any divergence problem. That is, the wavy nature of both
matter and light is an important physical property which cannot be neglected
for describing the motional dynamics of a trapped atom, even for small
Lamb-Dicke parameters.
| [
{
"version": "v1",
"created": "Thu, 17 Sep 1998 09:34:21 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Wallentowitz",
"S.",
""
],
[
"Vogel",
"W.",
""
],
[
"Knight",
"P. L.",
""
]
] |
quant-ph/9809050 | Constantin Brif | G. Ramon, C. Brif, and A. Mann (Technion, Haifa) | Governing dynamics by squeezing in a system of cold trapped ions | REVTeX, 5 pages, 2 figures, to appear in Phys. Rev. A | null | 10.1103/PhysRevA.59.736 | null | quant-ph | null | We consider a system of laser-cooled ions in a linear harmonic trap and study
the phenomenon of squeezing exchange between their internal and motional
degrees of freedom. An interesting relation between the quantum noise reduction
(squeezing) and the dynamical evolution is found when the internal and motional
subsystems are prepared in properly squeezed (intelligent) states.
Specifically, the evolution of the system is fully governed by the relative
strengths of spectroscopic and motional squeezing, including the phenomenon of
total cancellation of the interaction when the initial squeezing parameters are
equal.
| [
{
"version": "v1",
"created": "Thu, 17 Sep 1998 12:52:41 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Ramon",
"G.",
"",
"Technion, Haifa"
],
[
"Brif",
"C.",
"",
"Technion, Haifa"
],
[
"Mann",
"A.",
"",
"Technion, Haifa"
]
] |
quant-ph/9809051 | Constantin Brif | G. Ramon, C. Brif, and A. Mann (Technion, Haifa) | Collective effects in the collapse-revival phenomenon and squeezing in
the Dicke model | REVTeX, 13 pages, 19 figures, published in PRA | Phys.Rev. A58 (1998) 2506 | 10.1103/PhysRevA.58.2506 | null | quant-ph | null | Resonant interaction of a collection of two-level atoms with a single-mode
coherent cavity field is considered in the framework of the Dicke model. We
focus on the role of collective atomic effects in the phenomenon of collapses
and revivals of the Rabi oscillations. It is shown that the behavior of the
system strongly depends on the initial atomic state. In the case of the initial
half-excited Dicke state we account for a number of interesting phenomena. The
correlations between the atoms result in a suppression of the revival
amplitude, and the revival time is halved, compared to the uncorrelated
fully-excited and ground states. The phenomenon of squeezing of the radiation
field in the atom-field interaction is also discussed. For the initial
fully-excited and ground atomic states, the field is squeezed on the short-time
scale, and squeezing can be enhanced by increasing the number of atoms. Some
empirical formulas are found which describe the behavior of the system in
excellent agreement with numerical results. For the half-excited Dicke state,
the field can be strongly squeezed on the long-time scale in the case of two
atoms. This kind of squeezing is enhanced by increasing the intensity of the
initial coherent field and is of the same nature as revival-time squeezing in
the Jaynes-Cummings model. The appearance of this long-time squeezing can be
explained using the factorization approximation for semiclassical atomic
states.
| [
{
"version": "v1",
"created": "Thu, 17 Sep 1998 13:37:08 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Ramon",
"G.",
"",
"Technion, Haifa"
],
[
"Brif",
"C.",
"",
"Technion, Haifa"
],
[
"Mann",
"A.",
"",
"Technion, Haifa"
]
] |
quant-ph/9809052 | Constantin Brif | C. Brif and A. Mann (Technion, Haifa) | Phase-space formulation of quantum mechanics and quantum state
reconstruction for physical systems with Lie-group symmetries | REVTeX, 18 pages, no figures | null | 10.1103/PhysRevA.59.971 | null | quant-ph | null | We present a detailed discussion of a general theory of phase-space
distributions, introduced recently by the authors [J. Phys. A {\bf 31}, L9
(1998)]. This theory provides a unified phase-space formulation of quantum
mechanics for physical systems possessing Lie-group symmetries. The concept of
generalized coherent states and the method of harmonic analysis are used to
construct explicitly a family of phase-space functions which are postulated to
satisfy the Stratonovich-Weyl correspondence with a generalized traciality
condition. The symbol calculus for the phase-space functions is given by means
of the generalized twisted product. The phase-space formalism is used to study
the problem of the reconstruction of quantum states. In particular, we consider
the reconstruction method based on measurements of displaced projectors, which
comprises a number of recently proposed quantum-optical schemes and is also
related to the standard methods of signal processing. A general group-theoretic
description of this method is developed using the technique of harmonic
expansions on the phase space.
| [
{
"version": "v1",
"created": "Thu, 17 Sep 1998 15:07:10 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Brif",
"C.",
"",
"Technion, Haifa"
],
[
"Mann",
"A.",
"",
"Technion, Haifa"
]
] |
quant-ph/9809053 | Tilo Stroh | S. Brandt, H.D. Dahmen, E. Gjonaj, T. Stroh (Department of Physics,
Siegen University, Siegen, Germany) | Quantile Motion and Tunneling | 13 pages, LaTeX, elsart, 3 ps figures, submitted to Phys. Lett. A | Phys.Lett. A249 (1998) 265-270 | 10.1016/S0375-9601(98)00730-0 | null | quant-ph | null | The concepts of quantile position, trajectory, and velocity are defined. For
a tunneling quantum mechanical wave packet, it is proved that its quantile
position always stays behind that of a free wave packet with the same initial
parameters. In quantum mechanics the quantile trajectories are mathematically
identical to Bohm's trajectories. A generalization to three dimensions is
given.
| [
{
"version": "v1",
"created": "Thu, 17 Sep 1998 15:29:56 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Brandt",
"S.",
"",
"Department of Physics,\n Siegen University, Siegen, Germany"
],
[
"Dahmen",
"H. D.",
"",
"Department of Physics,\n Siegen University, Siegen, Germany"
],
[
"Gjonaj",
"E.",
"",
"Department of Physics,\n Siegen University, Siegen, Germany"
],
[
"Stroh",
"T.",
"",
"Department of Physics,\n Siegen University, Siegen, Germany"
]
] |
quant-ph/9809054 | Andrew Steane | Andrew M. Steane (Clarendon Laboratory, Oxford University) | Efficient fault-tolerant quantum computing | 21 pages plus 5 figures. Replaced with figures in new format to avoid
problems | null | 10.1038/20127 | null | quant-ph | null | Fault tolerant quantum computing methods which work with efficient quantum
error correcting codes are discussed. Several new techniques are introduced to
restrict accumulation of errors before or during the recovery. Classes of
eligible quantum codes are obtained, and good candidates exhibited. This
permits a new analysis of the permissible error rates and minimum overheads for
robust quantum computing. It is found that, under the standard noise model of
ubiquitous stochastic, uncorrelated errors, a quantum computer need be only an
order of magnitude larger than the logical machine contained within it in order
to be reliable. For example, a scale-up by a factor of 22, with gate error rate
of order $10^{-5}$, is sufficient to permit large quantum algorithms such as
factorization of thousand-digit numbers.
| [
{
"version": "v1",
"created": "Thu, 17 Sep 1998 17:04:09 GMT"
},
{
"version": "v2",
"created": "Fri, 18 Sep 1998 18:07:35 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Steane",
"Andrew M.",
"",
"Clarendon Laboratory, Oxford University"
]
] |
quant-ph/9809055 | Robert R. Tucci | Robert R. Tucci | An Optimization for Qubiter | 1 LaTeX file (3 pages), 1 eps file | null | null | null | quant-ph | null | In a previous paper, we described a computer program called Qubiter which can
decompose an arbitrary unitary matrix into elementary operations of the type
used in quantum computation. In this paper, we describe a method of reducing
the number of elementary operations in such decompositions.
| [
{
"version": "v1",
"created": "Thu, 17 Sep 1998 20:59:48 GMT"
},
{
"version": "v2",
"created": "Fri, 18 Sep 1998 01:03:37 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Tucci",
"Robert R.",
""
]
] |
quant-ph/9809056 | Haret Rosu | H.C. Rosu | Short survey of Darboux transformations | 17 pages, talk at Burgos Int. Workshop, Sept. 1998; v3 has misprints
corrected and several other improvements with respect to v2 | v2 in Proc. "Symmetries in Quantum Mechanics and Quantum Optics",
Burgos, Spain, Sept. 21-24, 1998, Eds. F.J. Herranz, A. Ballesteros, L.M.
Nieto, J. Negro, C.M. Perena, Serv. de Publ. Univ. Burgos, Burgos, Spain,
1999, ISBN 84-95211-08-4, pp. 301-315 | null | null | quant-ph | null | A selective chronological survey of Darboux transformations as related to
supersymmetric quantum mechanics, intertwining operators and inverse scattering
techniques is presented. Short comments are appended to each quotation and
basic concepts are explained in order to provide a useful primer
| [
{
"version": "v1",
"created": "Sat, 19 Sep 1998 02:38:30 GMT"
},
{
"version": "v2",
"created": "Fri, 2 Oct 1998 19:27:20 GMT"
},
{
"version": "v3",
"created": "Tue, 5 Oct 1999 22:26:14 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Rosu",
"H. C.",
""
]
] |
quant-ph/9809057 | Guo Guangcan | Lu-Ming Duan and Guang-Can Guo (University of Science and Technology
of China) | Quantum error avoiding codes versus quantum error correcting codes | 13 pages, latex | Phys.Lett. A255 (1999) 209-212 | 10.1016/S0375-9601(99)00183-8 | null | quant-ph | null | A general theory of quantum error avoiding codes is established, and new
light is shed on the relation between quantum error avoiding and correcting
codes. Quantum error avoiding codes are found to be a special type of highly
degenerate quantum error correcting codes. A combination of the ideas of
correcting and avoiding quantum errors may yield better codes. We give a
practical example.
| [
{
"version": "v1",
"created": "Sat, 19 Sep 1998 09:12:19 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Duan",
"Lu-Ming",
"",
"University of Science and Technology\n of China"
],
[
"Guo",
"Guang-Can",
"",
"University of Science and Technology\n of China"
]
] |
quant-ph/9809058 | Lorenza Viola | Lorenza Viola and Seth Lloyd | Decoherence control in quantum information processing: simple models | 7 pages, 2 figures; RevTeX style. Invited talk at the 4th
International Conference on Quantum Communication, Measurement & Computing
(Evanston, August 22-27, 1998) | null | null | null | quant-ph | null | We explore a strategy for protecting the evolution of a qubit against the
effects of environmental noise based on the application of controlled
time-dependent perturbations. In the case of a purely decohering coupling, an
explicit sequence of control operations is designed, able to average out the
decoherence of the qubit with high efficiency. We argue that, in principle, the
effects of arbitrary qubit-environment interactions can be removed through
suitable decoupling perturbations acting on the system dynamics over time
scales comparable to the correlation time of the environment.
| [
{
"version": "v1",
"created": "Sat, 19 Sep 1998 21:53:19 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Viola",
"Lorenza",
""
],
[
"Lloyd",
"Seth",
""
]
] |
quant-ph/9809059 | Alvaro L. | C. Cisneros, R. P. Mart\'inez-y-Romero, H. N. Nu\~nez-Yepez, A.L.
Salas-Brito | Limitations on the superposition principle: superselection rules in
non-relativistic quantum mechanics | 22 pages, no figures | Eur.J.Phys. 19 (1998) 237-243 | 10.1088/0143-0807/19/3/005 | null | quant-ph | null | The superposition principle is a very basic ingredient of quantum theory.
What may come as a surprise to many students, and even to many practitioners of
the quantum craft, is tha superposition has limitations imposed by certain
requirements of the theory. The discussion of such limitations arising from the
so-called superselection rules is the main purpose of this paper. Some of their
principal consequences are also discussed. The univalence, mass and particle
number superselection rules of non-relativistic quantum mechanics are also
derived using rather simple methods.
| [
{
"version": "v1",
"created": "Sat, 19 Sep 1998 22:52:03 GMT"
}
] | 2016-08-15T00:00:00 | [
[
"Cisneros",
"C.",
""
],
[
"Martínez-y-Romero",
"R. P.",
""
],
[
"Nuñez-Yepez",
"H. N.",
""
],
[
"Salas-Brito",
"A. L.",
""
]
] |
quant-ph/9809060 | Bruno Galvan | B. Galvan | A classical ontology for quantum phenomena | 10 pages, LaTeX | null | null | null | quant-ph | null | Quantum mechanics states that a particle emitted at point (x_1,t_1) and
detected at point (x_2,t_2) does not travel along a definite path between the
two points. This conclusion arises essentially from the analysis of the
two-slit experiment, which implicitly assumes (as in the demonstration of the
EPR paradox) that a property we will call Independence Property holds. This
paper shows that this assumption is not indispensable. Abandoning the
assumption allows to develop an ontology where particle motion is described by
classical paths and quantum phenomena are interpreted as a manifestation of a
contingent law, i.e., of a law deriving from the boundary conditions of the
universe, such as the second law of thermodynamics. The paper also proposes an
equation having a typical quantum-like structure to represent the contingent
laws of the universe.
| [
{
"version": "v1",
"created": "Sun, 20 Sep 1998 17:03:22 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Galvan",
"B.",
""
]
] |
quant-ph/9809061 | M. Czachor | Marek Czachor and Jan Naudts | Microscopic Foundation of Nonextensive Statistics | revtex | Phys.Rev. E59 (1999) 2497 | 10.1103/PhysRevE.59.R2497 | null | quant-ph | null | Combination of the Liouville equation with the q-averaged energy $U_q =
<H>_q$ leads to a microscopic framework for nonextensive q-thermodynamics. The
resulting von Neumann equation is nonlinear: $i\dot\rho=[H,\rho^q]$. In spite
of its nonlinearity the dynamics is consistent with linear quantum mechanics of
pure states. The free energy $F_q=U_q-TS_q$ is a stability function for the
dynamics. This implies that q-equilibrium states are dynamically stable. The
(microscopic) evolution of $\rho$ is reversible for any q, but for $q\neq 1$
the corresponding macroscopic dynamics is irreversible.
| [
{
"version": "v1",
"created": "Tue, 22 Sep 1998 09:19:25 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Czachor",
"Marek",
""
],
[
"Naudts",
"Jan",
""
]
] |
quant-ph/9809062 | Frank Antonsen | Frank Antonsen | Sturmian Basis Functions for the Harmonic Oscillator | LaTeX, with 3 postscript figures | null | 10.1103/PhysRevA.60.812 | null | quant-ph | null | We define Sturmian basis functions for the harmonic oscillator and
investigate whether recent insights into Sturmians for Coulomb-like potentials
can be extended to this important potential. We also treat many body problems
such as coupling to a bath of harmonic oscillators. Comments on coupled
oscillators and time-dependent potentials are also made.
It is argued that the Sturmian method amounts to a non-perturbative
calculation of the energy levels, but the limitations of the method is also
pointed out, and the cause of this limitation is found to be related to the
divergence of the potential. Thus the divergent nature of the anharmonic
potential leads to the Sturmian method being less acurate than in the Coulomb
case. We discuss how modified anharmonic oscillator potentials, which are well
behaved at infinity, leads to a rapidly converging Sturmian approximation.
| [
{
"version": "v1",
"created": "Tue, 22 Sep 1998 11:23:23 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Antonsen",
"Frank",
""
]
] |
quant-ph/9809063 | John Calsamiglia | N. L\"utkenhaus, J. Calsamiglia, K-A. Suominen | On Bell measurements for teleportation | 7 pages, 3 figures. Final version to appear in Phys.Rev. A | Phys.Rev. A59 (1999) 3295 | 10.1103/PhysRevA.59.3295 | null | quant-ph | null | In this paper we investigate the possibility to make complete Bell
measurements on a product Hilbert space of two two-level bosonic systems. We
restrict our tools to linear elements, like beam splitters and phase shifters,
delay lines and electronically switched linear elements, photo-detectors, and
auxiliary bosons. As a result we show that with these tools a never failing
Bell measurement is impossible.
| [
{
"version": "v1",
"created": "Tue, 22 Sep 1998 18:23:10 GMT"
},
{
"version": "v2",
"created": "Thu, 28 Jan 1999 09:13:13 GMT"
}
] | 2016-08-15T00:00:00 | [
[
"Lütkenhaus",
"N.",
""
],
[
"Calsamiglia",
"J.",
""
],
[
"Suominen",
"K-A.",
""
]
] |
quant-ph/9809064 | Zanardi Paolo | Paolo Zanardi (Institute for Scientific Interchange Foundation, and
Unit\`a INFM, Politecnico di Torino) | Symmetrizing Evolutions | Presentation improved, to appear in Phys. Lett. A. 5 pages LaTeX, no
figures | Phys.Lett. A258 (1999) 77 | 10.1016/S0375-9601(99)00365-5 | null | quant-ph | null | We introduce quantum procedures for making $\cal G$-invariant the dynamics of
an arbitrary quantum system S, where $\cal G$ is a finite group acting on the
space state of S. Several applications of this idea are discussed. In
particular when S is a N-qubit quantum computer interacting with its
environment and $\cal G$ the symmetric group of qubit permutations, the
resulting effective dynamics admits noiseless subspaces. Moreover it is shown
that the recently introduced iterated-pulses schemes for reducing decoherence
in quantum computers fit in this general framework. The noise-inducing
component of the Hamiltonian is filtered out by the symmetrization procedure
just due to its transformation properties.
| [
{
"version": "v1",
"created": "Tue, 22 Sep 1998 17:06:02 GMT"
},
{
"version": "v2",
"created": "Wed, 9 Jun 1999 09:04:48 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Zanardi",
"Paolo",
"",
"Institute for Scientific Interchange Foundation, and\n Unità INFM, Politecnico di Torino"
]
] |
quant-ph/9809065 | Stefan Weigert | Stefan Weigert | Reconstruction of spin states and its conceptual implications | Latex2e, 9 pages | null | null | null | quant-ph | null | State reconstruction for quantum spins is reviewed. Emphasis is on
non-tomographic approaches which are based on measurements performed with a
Stern-Gerlach apparatus. Two consequences of successfully implemented state
reconstruction are pointed out. First, it allows one to determine
experimentally the expectation value of an arbitrary operator without a device
measuring it. Second, state reconstruction suggests a reformulation of
Schroedinger's equation in terms of expectation values only, without explicit
reference to a wave function or a density operator.
| [
{
"version": "v1",
"created": "Tue, 22 Sep 1998 16:47:31 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Weigert",
"Stefan",
""
]
] |
quant-ph/9809066 | Ariel Caticha | Ariel Caticha | The assumptions underlying the consistent-amplitude approach to quantum
theory | This contains a reply to a comment by J. Finkelstein
(quant-ph/9809017) | null | null | null | quant-ph | null | In this note I expand further on the main assumptions leading to the
consistent-amplitude approach to quantum theory and I offer a reply to Jerry
Finkelstein's recent comment (quant-ph/9809017) concerning my argument for the
linearity of quantum mechanics (Phys. Rev. A57, 1572 (1998)).
| [
{
"version": "v1",
"created": "Tue, 22 Sep 1998 17:23:47 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Caticha",
"Ariel",
""
]
] |
quant-ph/9809067 | S. F. Yelin | M. D. Lukin, S. F. Yelin, M. Fleischhauer, and M. O. Scully | Interacting Dark Resonances: Interference Effects Induced by Coherently
Altered Quantum Superpositions | 4 pages, 3 figures, RevTeX, submitted to PRL; changed three numbers
in Fig. 3 (caption) | Phys.Rev. A60 (1999) 3225-3228 | 10.1103/PhysRevA.60.3225 | null | quant-ph | null | We predict the possibility of sharp, high-contrast resonances in the optical
response of a broad class of systems, wherein interference effects are
generated by coherent perturbation or interaction of dark states. The
properties of these resonances can be manipulated to design a desired atomic
response.
| [
{
"version": "v1",
"created": "Wed, 23 Sep 1998 02:32:33 GMT"
},
{
"version": "v2",
"created": "Thu, 5 Nov 1998 16:29:15 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Lukin",
"M. D.",
""
],
[
"Yelin",
"S. F.",
""
],
[
"Fleischhauer",
"M.",
""
],
[
"Scully",
"M. O.",
""
]
] |
quant-ph/9809068 | Bg Sidharth | B.G. Sidharth | Stochastic Conservation Laws? | 5 pages, TeX | Chaos Solitons Fractals 11 (2000) 1037-1039 | 10.1016/S0960-0779(98)00324-5 | null | quant-ph gr-qc hep-th | null | We examine conservation laws, typically the conservation of linear momentum,
in the light of a recent successful formulation of fermions as Kerr-Newman type
Black Holes, which are created fluctuationally from a background Zero Point
Field. We conclude that these conservation laws are to be taken in the spirit
of thermodynamic laws.
| [
{
"version": "v1",
"created": "Wed, 23 Sep 1998 09:52:29 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Sidharth",
"B. G.",
""
]
] |
quant-ph/9809069 | Iwo Bialynicki-Birula | Iwo Bialynicki-Birula | Nonstandard introduction to squeezing of the electromagnetic field | Presented at the XXXVIII Cracow School of Theoretical Physics,
Zakopane, June 1-10, 1998. To be published in Acta Physica Polonica B | Acta Phys.Polon. B29 (1998) 3569-3590 | null | null | quant-ph | null | This article contains a review of an alternative theory of squeezing, based
entirely on the wave function description of the squeezed states. Quantum field
theoretic approach is used to describe the squeezing of the electromagnetic
field in its most complete form that takes into account temporal and spatial
characteristics of the squeezed state. An analog of the Wigner function for the
full electromagnetic field is introduced and expressed in terms of second order
correlation functions. The field-theoretic approach enables one to study the
propagation of the ``squeezing wave'' in space-time. A simple example of weak
squeezing, that allows for all calculations to be done analytically, is
discussed in detail.
| [
{
"version": "v1",
"created": "Wed, 23 Sep 1998 11:53:32 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Bialynicki-Birula",
"Iwo",
""
]
] |
quant-ph/9809070 | Piotr Garbaczewski | P. Garbaczewski | Third Newton Law in the Mean and Perturbations of Noise | Latex file | null | null | null | quant-ph chao-dyn hep-th nlin.CD | null | We analyze an isothermal Brownian motion of particle ensembles in the
Smoluchowski approximation.
Contrary to standard procedures, the environmental recoil effects associated
with locally induced heat flows are not completely disregarded. The main
technical tool in the study of such weakly-out-of equilibrium systems is a
consequent exploitation of the Hamilton-Jacobi equation. The third Newton law
in the mean is utilised to generate diffusion-type processes which are either
anomalous (enhanced), or generically non-dispersive.
| [
{
"version": "v1",
"created": "Wed, 23 Sep 1998 12:14:02 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Garbaczewski",
"P.",
""
]
] |
quant-ph/9809071 | Lorenza Viola | Lorenza Viola, Emanuel Knill, and Seth Lloyd | Dynamical Decoupling of Open Quantum Systems | 4 pages, no figures; Plain ReVTeX. Final version to appear in
Physical Review Letters | Phys.Rev.Lett.82:2417-2421,1999 | 10.1103/PhysRevLett.82.2417 | null | quant-ph | null | We propose a novel dynamical method for beating decoherence and dissipation
in open quantum systems. We demonstrate the possibility of filtering out the
effects of unwanted (not necessarily known) system-environment interactions and
show that the noise-suppression procedure can be combined with the capability
of retaining control over the effective dynamical evolution of the open quantum
system. Implications for quantum information processing are discussed.
| [
{
"version": "v1",
"created": "Thu, 24 Sep 1998 00:34:49 GMT"
},
{
"version": "v2",
"created": "Thu, 11 Feb 1999 23:15:28 GMT"
}
] | 2011-08-04T00:00:00 | [
[
"Viola",
"Lorenza",
""
],
[
"Knill",
"Emanuel",
""
],
[
"Lloyd",
"Seth",
""
]
] |
quant-ph/9809072 | null | Carl Bender (Washington U.), Stefan Boettcher (Los Alamos and Clark
Atlanta U.), and Peter Meisinger (Washington U.) | PT-Symmetric Quantum Mechanics | 20 pages RevTex, 23 ps-figures | J.Math.Phys. 40 (1999) 2201-2229 | 10.1063/1.532860 | null | quant-ph cond-mat hep-th | null | This paper proposes to broaden the canonical formulation of quantum
mechanics. Ordinarily, one imposes the condition $H^\dagger=H$ on the
Hamiltonian, where $\dagger$ represents the mathematical operation of complex
conjugation and matrix transposition. This conventional Hermiticity condition
is sufficient to ensure that the Hamiltonian $H$ has a real spectrum. However,
replacing this mathematical condition by the weaker and more physical
requirement $H^\ddag=H$, where $\ddag$ represents combined parity reflection
and time reversal ${\cal PT}$, one obtains new classes of complex Hamiltonians
whose spectra are still real and positive. This generalization of Hermiticity
is investigated using a complex deformation $H=p^2+x^2(ix)^\epsilon$ of the
harmonic oscillator Hamiltonian, where $\epsilon$ is a real parameter. The
system exhibits two phases: When $\epsilon\geq0$, the energy spectrum of $H$ is
real and positive as a consequence of ${\cal PT}$ symmetry. However, when
$-1<\epsilon<0$, the spectrum contains an infinite number of complex
eigenvalues and a finite number of real, positive eigenvalues because ${\cal
PT}$ symmetry is spontaneously broken. The phase transition that occurs at
$\epsilon=0$ manifests itself in both the quantum-mechanical system and the
underlying classical system. Similar qualitative features are exhibited by
complex deformations of other standard real Hamiltonians
$H=p^2+x^{2N}(ix)^\epsilon$ with $N$ integer and $\epsilon>-N$; each of these
complex Hamiltonians exhibits a phase transition at $\epsilon=0$. These ${\cal
PT}$-symmetric theories may be viewed as analytic continuations of conventional
theories from real to complex phase space.
| [
{
"version": "v1",
"created": "Thu, 24 Sep 1998 02:27:05 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Bender",
"Carl",
"",
"Washington U."
],
[
"Boettcher",
"Stefan",
"",
"Los Alamos and Clark\n Atlanta U."
],
[
"Meisinger",
"Peter",
"",
"Washington U."
]
] |
quant-ph/9809073 | Piotr Rozmej | P. Rozmej and R. Arvieu | Towards new understanding of nuclear rotation | 4 pages, 2 figures, LaTeX (appb.sty included), Presented at the
XXXIII Zakopane School of Physics, Zakopane, Poland, September 1-9, 1998. To
appear in Acta Phys. Polon. B (1999) | Acta Phys.Polon.B30:799-802,1999 | null | null | quant-ph nucl-th | null | Properties of time evolution of wave packets built up from rotator
eigenstates are discussed. The mechanism of perfect cloning of the initial wave
packet for "circular states" at fractional revival times is explained. The
smooth transition from "circular" to "linear" through intermediate "elliptic"
is described. Example of time evolution of a nuclear wave packet created in
Coulomb excitation mechanism is presented.
| [
{
"version": "v1",
"created": "Thu, 24 Sep 1998 09:48:54 GMT"
}
] | 2011-04-15T00:00:00 | [
[
"Rozmej",
"P.",
""
],
[
"Arvieu",
"R.",
""
]
] |
quant-ph/9809074 | T. Hakioglu | T. Hakioglu | Finite-dimensional Schwinger basis, deformed symmetries, Wigner
function, and an algebraic approach to quantum phase | 19 pages, no figures | J.Phys.A31:6975-6994,1998 | 10.1088/0305-4470/31/33/008 | null | quant-ph astro-ph math-ph math.MP | null | Schwinger's finite (D) dimensional periodic Hilbert space representations are
studied on the toroidal lattice ${\ee Z}_{D} \times {\ee Z}_{D}$ with specific
emphasis on the deformed oscillator subalgebras and the generalized
representations of the Wigner function. These subalgebras are shown to be
admissible endowed with the non-negative norm of Hilbert space vectors. Hence,
they provide the desired canonical basis for the algebraic formulation of the
quantum phase problem. Certain equivalence classes in the space of labels are
identified within each subalgebra, and connections with area-preserving
canonical transformations are examined. The generalized representations of the
Wigner function are examined in the finite-dimensional cyclic Schwinger basis.
These representations are shown to conform to all fundamental conditions of the
generalized phase space Wigner distribution. As a specific application of the
Schwinger basis, the number-phase unitary operator pair in ${\ee Z}_{D} \times
{\ee Z}_{D}$ is studied and, based on the admissibility of the underlying
q-oscillator subalgebra, an {\it algebraic} approach to the unitary quantum
phase operator is established. This being the focus of this work, connections
with the Susskind-Glogower- Carruthers-Nieto phase operator formalism as well
as standard action-angle Wigner function formalisms are examined in the
infinite-period limit. The concept of continuously shifted Fock basis is
introduced to facilitate the Fock space representations of the Wigner function.
| [
{
"version": "v1",
"created": "Thu, 24 Sep 1998 10:44:03 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Hakioglu",
"T.",
""
]
] |
quant-ph/9809075 | Masanori Ohya | Masanori Ohya and Natsuki Masuda | NP problem in quantum algorithm | 8 pages, 1 figure, Latex2e | OpenSyst.Info.Dyn.7:33-39,2000 | null | null | quant-ph | null | In complexity theory, there exists a famous unsolved problem whether NP can
be P or not. In this paper, we discuss this aspect in SAT (satisfiability)
problem, and it is shown that the SAT can be solved in plynomial time by means
of quantum algorithm.
| [
{
"version": "v1",
"created": "Thu, 24 Sep 1998 12:05:56 GMT"
},
{
"version": "v2",
"created": "Sun, 13 Dec 1998 09:09:23 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Ohya",
"Masanori",
""
],
[
"Masuda",
"Natsuki",
""
]
] |
quant-ph/9809076 | Johannes Denschlag | Johannes Denschlag, Donatella Cassettari, Joerg Schmiedmayer | Guiding Neutral Atoms with a Wire | 4 pages, 6 figures, submitted to PRL | Phys.Rev.Lett. 82 (1999) 2014-2017 | 10.1103/PhysRevLett.82.2014 | null | quant-ph | null | We demonstrate guiding of cold neutral atoms along a current carrying wire.
Atoms either move in Kepler-like orbits around the wire or are guided in a
potential tube on the side of the wire which is created by applying an
additional homogeneous bias field. These atom guides are very versatile and
promising for applications in atom optics.
| [
{
"version": "v1",
"created": "Thu, 24 Sep 1998 15:49:40 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Denschlag",
"Johannes",
""
],
[
"Cassettari",
"Donatella",
""
],
[
"Schmiedmayer",
"Joerg",
""
]
] |
quant-ph/9809077 | Joerg Schmiedmayer | Joerg Schmiedmayer | Quantum Wires and Quantum Dots for Neutral Atoms | 6 pages, 3 figures, EPJ D in print | Eur.Phys.J.D4:57,1998 | 10.1007/s100530050184 | null | quant-ph | null | By placing changeable nanofabricated structures (wires, dots, etc.) on an
atom mirror one can design guiding and trapping potentials for atoms. These
potentials are similar to the electrostatic potentials which trap and guide
electrons in semiconductor quantum devices like quantum wires and quantum dots.
This technique will allow the fabrication of nanoscale atom optical devices.
| [
{
"version": "v1",
"created": "Thu, 24 Sep 1998 17:28:37 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Schmiedmayer",
"Joerg",
""
]
] |
quant-ph/9809078 | Eric Rains | Eric M. Rains | A rigorous treatment of distillable entanglement | 11 pages, AMSTeX, no figures; minor corrections and clarifications
10/12/98 | null | 10.1103/PhysRevA.60.173 | null | quant-ph | null | The notion of distillable entanglement is one of the fundamental concepts of
quantum information theory. Unfortunately, there is an apparent mismatch
between the intuitive and rigorous definitions of distillable entanglement. To
be precise, the existing rigorous definitions impose the constraint that the
distilation protocol produce an output of constant dimension. It is therefore
conceivable that this unnecessary constraint might have led to underestimation
of the true distillable entanglement. We give a new definition of distillable
entanglement which removes this constraint, but could conceivably overestimate
the true value. Since the definitions turn out to be equivalent, neither
underestimation nor overestimation is possible, and both definitions are
arguably correct
| [
{
"version": "v1",
"created": "Thu, 24 Sep 1998 22:30:24 GMT"
},
{
"version": "v2",
"created": "Mon, 12 Oct 1998 16:07:05 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Rains",
"Eric M.",
""
]
] |
quant-ph/9809079 | Chang-Pu Sun | C.P.Sun, S.X.Yu and Y.B.Gao | Gardiner's phonon for Bose-Einstein Condensation: A physical realization
of the $q$-deformed Boson | Revtex 5 pages, address: Institute of Theoretical Physics, Academia
Sinica, Beijing 100080, China; e-mail:[email protected]; www:
http://www.itp.ac.cn/~suncp | null | null | ITP-AC-quantum 98-11 | quant-ph math-ph math.MP | null | The Gardiner's phonon presented for a particle-number conserving
approximation method to describe the dynamics of Bose-Einstein Condesation
(BEC) (C.W. Gardiner, Phys. Rev. A 56, 1414 (1997)) is shown to be a physical
realization of the $q$-deformed boson, which was abstractly developed in
quantum group theory. On this observation, the coherent output of BEC atoms
driven by a radio frequency (r.f) field is analyzed in the viewpoint of a
$q$-deformed Fock space. It is illustrated that the $q$-deformation of bosonic
commutation relation corresponds to the non-ideal BEC with the finite particle
number $N$ of condensated atoms. Up to order 1/N, the coherent output state of
the untrapped atoms minimizes the uncertainty relation like a coherent state
does in the ideal case of BEC that $N$ approaches infinity or $q=1-2/N$
approaches one.
| [
{
"version": "v1",
"created": "Sat, 26 Sep 1998 22:53:49 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sun",
"C. P.",
""
],
[
"Yu",
"S. X.",
""
],
[
"Gao",
"Y. B.",
""
]
] |
quant-ph/9809080 | null | P. Ao (Umea University) | Quantum Dynamics of Topological Singularities: Feynman's Influence
Functional Approach | revtex, based on my talk given at Conference 50 years from Feynman's
paper | null | null | null | quant-ph cond-mat | null | Starting from the microscopic theory of Bardeen-Cooper-Schrieffer (BCS) for
the fermionic superfluids, we show that the vortex dynamics can be followed
naturally by extending Feynman's influence functional approach to incorporate
the transverse force.
There is a striking mutual independence of the transverse and longitudinal
influences:
The former has the topological origin and is insensitive to details, while
the latter corresponds to the well-known damping kernel depending on details.
| [
{
"version": "v1",
"created": "Sun, 27 Sep 1998 09:18:41 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Ao",
"P.",
"",
"Umea University"
]
] |
quant-ph/9809081 | Dr. Daniel A. Lidar | D.A. Lidar, D. Bacon and K.B. Whaley (UC Berkeley) | Concatenating Decoherence Free Subspaces with Quantum Error Correcting
Codes | 4 pages, no figures. Several changes. To appear in PRL | Phys.Rev.Lett. 82 (1999) 4556-4559 | 10.1103/PhysRevLett.82.4556 | null | quant-ph cs.IT math-ph math.IT math.MP | null | An operator sum representation is derived for a decoherence-free subspace
(DFS) and used to (i) show that DFSs are the class of quantum error correcting
codes (QECCs) with fixed, unitary recovery operators, and (ii) find explicit
representations for the Kraus operators of collective decoherence. We
demonstrate how this can be used to construct a concatenated DFS-QECC code
which protects against collective decoherence perturbed by independent
decoherence. The code yields an error threshold which depends only on the
perturbing independent decoherence rate.
| [
{
"version": "v1",
"created": "Mon, 28 Sep 1998 02:08:00 GMT"
},
{
"version": "v2",
"created": "Wed, 28 Apr 1999 17:02:34 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Lidar",
"D. A.",
"",
"UC Berkeley"
],
[
"Bacon",
"D.",
"",
"UC Berkeley"
],
[
"Whaley",
"K. B.",
"",
"UC Berkeley"
]
] |
quant-ph/9809082 | Eric M. Rains | E. M. Rains | An improved bound on distillable entanglement | 14 pages, no figures. A significant erratum in theorems 4 and 5 has
been fixed | null | 10.1103/PhysRevA.60.179 | null | quant-ph | null | The best bound known on 2-locally distillable entanglement is that of Vedral
and Plenio, involving a certain measure of entanglement based on relative
entropy. It turns out that a related argument can be used to give an even
stronger bound; we give this bound, and examine some of its properties. In
particular, and in contrast to the earlier bounds, the new bound is not
additive in general. We give an example of a state for which the bound fails to
be additive, as well as a number of states for which the bound is additive.
| [
{
"version": "v1",
"created": "Mon, 28 Sep 1998 15:48:13 GMT"
},
{
"version": "v2",
"created": "Mon, 30 Oct 2000 20:31:58 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Rains",
"E. M.",
""
]
] |
quant-ph/9809083 | Petre Dita | Petre Di\c{t}\u{a} (NIPNE - Bucharest) | Poisson-Lie Structures and Quantisation with Constraints | 13 pages, Latex | null | null | null | quant-ph | null | We develop here a simple quantisation formalism that make use of Lie algebra
properties of the Poisson bracket. When the brackets $\{H,\phi_i\}$ and
$\{\phi_i,\phi_j\}$, where $H$ is the Hamiltonian and $\phi_i$ are primary and
secondary constraints, can be expressed as functions of $H$ and $\phi_i$
themselves, the Poisson bracket defines a Poisson-Lie structure. When this
algebra has a finite dimension a system of first order partial differential
equations is established whose solutions are the observables of the theory. The
method is illustrated with a few examples.
| [
{
"version": "v1",
"created": "Mon, 28 Sep 1998 18:08:47 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Diţă",
"Petre",
"",
"NIPNE - Bucharest"
]
] |
quant-ph/9809084 | Esteban Calzetta | Esteban Calzetta and Bei-lok Hu | Influence Action and decoherence of hydrodynamic modes | 5 pages, no figures | Phys.Rev.D59:065018,1999 | 10.1103/PhysRevD.59.065018 | umdpp 99-025 | quant-ph gr-qc hep-th | null | We derive an influence action for the heat diffusion equation and from its
spectral dependence show that long wavelength hydrodynamic modes are most
readily decohered. The result is independent of the details of the microscopic
dynamics, and follows from general principles alone.
| [
{
"version": "v1",
"created": "Mon, 28 Sep 1998 20:12:26 GMT"
}
] | 2011-08-04T00:00:00 | [
[
"Calzetta",
"Esteban",
""
],
[
"Hu",
"Bei-lok",
""
]
] |
Subsets and Splits
No saved queries yet
Save your SQL queries to embed, download, and access them later. Queries will appear here once saved.