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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
quant-ph/0701134 | Marco Piani | M. Horodecki, M. Piani | On quantum advantage in dense coding | 8 pages, comments welcome; added results about a monogamy relation
between quantum advantage in dense coding and entanglement of purification,
title and abstract changed, references updated, requires IEEEtran.cls | J. Phys. A: Math. Theor. 45 (2012) 105306 | 10.1088/1751-8113/45/10/105306 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The quantum advantage of dense coding is studied, considering general
encoding quantum operations. Particular attention is devoted to the case of
many senders, and it is shown that restrictions on the possible operations on
the senders' side may make some quantum state useless for dense-coding. It is
shown, e.g., that some states are useful for dense coding if the senders can
communicate classically (but not quantumly), yet they cannot be used for dense
coding, if classical communication is not allowed. These no-go results are
actually independent of the particular quantification of the quantum advantage,
being valid for any reasonable choice. It is further shown that the quantum
advantage of dense coding satisfies a monogamy relation with the so-called
entanglement of purification.
| [
{
"version": "v1",
"created": "Thu, 18 Jan 2007 19:06:02 GMT"
},
{
"version": "v2",
"created": "Fri, 11 Sep 2009 15:48:39 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Horodecki",
"M.",
""
],
[
"Piani",
"M.",
""
]
]
|
quant-ph/0701135 | Zhaohui Wei | Zhaohui Wei and Mingsheng Ying | Linearity and Quantum Adiabatic Theorem | 4 pages, 1 figure. comments are welcome | null | null | null | quant-ph | null | We show that in a quantum adiabatic evolution, even though the adiabatic
approximation is valid, the total phase of the final state indicated by the
adiabatic theorem may evidently differ from the actual total phase. This
invalidates the application of the linearity and the adiabatic approximation
simultaneously. Besides, based on this observation we point out the mistake in
the traditional proof for the adiabatic theorem. This mistake is the root of
the troubles that the adiabatic theorem has met. We also show that a similar
mistake remains in some recent modifications of the traditional adiabatic
theorem attempting to eliminate the troubles.
| [
{
"version": "v1",
"created": "Fri, 19 Jan 2007 01:22:13 GMT"
},
{
"version": "v2",
"created": "Sat, 17 Feb 2007 02:36:15 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Wei",
"Zhaohui",
""
],
[
"Ying",
"Mingsheng",
""
]
]
|
quant-ph/0701136 | Andrew Stewart M | A.M.Stewart | Angular momentum of the physical electron | revision, 3 pages pdf | Canadian Journal of Physics 87 (2) 151-152 (2009) | 10.1139/P08-116 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The angular momentum of the physical electron, modelled as a Dirac fermion
coupled to the electromagnetic field, is found to be hbar/2, the same as that
of a bare Dirac fermion and independent of the size of the electric charge.
| [
{
"version": "v1",
"created": "Fri, 19 Jan 2007 02:32:05 GMT"
},
{
"version": "v2",
"created": "Wed, 29 Apr 2009 10:37:10 GMT"
}
]
| 2009-04-29T00:00:00 | [
[
"Stewart",
"A. M.",
""
]
]
|
quant-ph/0701137 | Ho Trung Dung | Tuan Anh Nguyen and Ho Trung Dung | Spontaneous decay of an excited atom placed near a rectangular plate | 5 pages, 5 figures | null | 10.1140/epjd/e2007-00268-4 | null | quant-ph | null | Using the Born expansion of the Green tensor, we consider the spontaneous
decay rate of an excited atom placed in the vicinity of a rectangular plate. We
discuss the limitations of the commonly used simplifying assumption that the
plate extends to infinity in the lateral directions and examine the effects of
the atomic dipole moment orientation, atomic position, and plate boundary and
thickness on the atomic decay rate. In particular, it is shown that in the
boundary region, the spontaneous decay rate can be strongly modified.
| [
{
"version": "v1",
"created": "Fri, 19 Jan 2007 02:50:37 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Nguyen",
"Tuan Anh",
""
],
[
"Dung",
"Ho Trung",
""
]
]
|
quant-ph/0701138 | Line Hjortsh{\o}j Pedersen | Line Hjortshoj Pedersen, Klaus Molmer and Niels Martin Moller | Fidelity of quantum operations | 5 pages, no figures. The text has been modified to acknowledge that
our Eq.(1) has appeared already in quant-ph/0503243 and quant-ph/0512217 | Phys. Lett. A 367 (2007), no. 1-2, 47--51. | 10.1016/j.physleta.2007.02.069 | null | quant-ph | null | We present a derivation and numerous applications of a compact explicit
formula for the average fidelity of a quantum operation on a finite dimensional
quantum system. The formula can be applied to averages over particularly
relevant subspaces; it is easily generalized to multi-component systems, and as
a special result, we show that when the same completely positive
trace-preserving map is applied to a large number of qubits with one-bit
fidelity F close to unity, the average fidelity of the operation on the full
K-bit register scales as $F^{3K/2}$.
| [
{
"version": "v1",
"created": "Fri, 19 Jan 2007 10:31:41 GMT"
},
{
"version": "v2",
"created": "Mon, 5 Feb 2007 03:53:24 GMT"
}
]
| 2009-02-26T00:00:00 | [
[
"Pedersen",
"Line Hjortshoj",
""
],
[
"Molmer",
"Klaus",
""
],
[
"Moller",
"Niels Martin",
""
]
]
|
quant-ph/0701139 | Jean-Philippe Karr | Jean-Philippe Karr (LKB - Jussieu, DPM), Laurent Hilico (LKB -
Jussieu, DPM) | High accuracy results for the energy levels of the molecular ions H2+,
D2+ and HD+, up to J=2 | 11 pages | Journal of Physics B: Atomic, Molecular and Optical Physics 39,
2095 (2006) | 10.1088/0953-4075/39/8/024 | null | quant-ph | null | We present a nonrelativistic calculation of the rotation-vibration levels of
the molecular ions H2+, D2+ and HD+, relying on the diagonalization of the
exact three-body Hamiltonian. The J=2 levels are obtained with a very high
accuracy of 10^{-14} a.u. (for most levels) representing an improvement by five
orders of magnitude over previous calculations. The accuracy is also improved
for the J=1 levels of H2+ and D2+ with respect to earlier works. Moreover, we
have computed the sensitivities of the energy levels with respect to the mass
ratios, allowing these levels to be used for metrological purposes.
| [
{
"version": "v1",
"created": "Fri, 19 Jan 2007 13:10:11 GMT"
}
]
| 2017-02-20T00:00:00 | [
[
"Karr",
"Jean-Philippe",
"",
"LKB - Jussieu, DPM"
],
[
"Hilico",
"Laurent",
"",
"LKB -\n Jussieu, DPM"
]
]
|
quant-ph/0701140 | Karl Tordrup | Karl Tordrup and Klaus M{\o}lmer | Quantum state reconstruction with imperfect rotations on an
inhomogeneously broadened ensemble of qubits | 6 pages, 5 figures | null | 10.1103/PhysRevA.75.042318 | null | quant-ph | null | We present a method for performing quantum state reconstruction on qubits and
qubit registers in the presence of decoherence and inhomogeneous broadening.
The method assumes only rudimentary single qubit rotations as well as knowledge
of decoherence and loss mechanisms. We show that full state reconstruction is
possible even in the case where single qubit rotations may only be performed
imperfectly. Furthermore we show that for ensemble quantum computing proposals,
quantum state reconstruction is possible even if the ensemble experiences
inhomogeneous broadening and if only imperfect qubit manipulations are
available during state preparation and reconstruction.
| [
{
"version": "v1",
"created": "Fri, 19 Jan 2007 13:48:40 GMT"
}
]
| 2016-08-14T00:00:00 | [
[
"Tordrup",
"Karl",
""
],
[
"Mølmer",
"Klaus",
""
]
]
|
quant-ph/0701141 | S. G. Rajeev | S. G. Rajeev (University of Rochester) | Dissipative Mechanics Using Complex-Valued Hamiltonians | null | null | null | null | quant-ph cond-mat.stat-mech hep-th math-ph math.DS math.MP math.SG | null | We show that a large class of dissipative systems can be brought to a
canonical form by introducing complex co-ordinates in phase space and a
complex-valued hamiltonian. A naive canonical quantization of these systems
lead to non-hermitean hamiltonian operators. The excited states are unstable
and decay to the ground state . We also compute the tunneling amplitude across
a potential barrier.
| [
{
"version": "v1",
"created": "Fri, 19 Jan 2007 15:27:56 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Rajeev",
"S. G.",
"",
"University of Rochester"
]
]
|
quant-ph/0701142 | Fr\'ed\'eric Dupuis | Fr\'ed\'eric Dupuis, Nicolas Gisin, Avinatan Hassidim, Andr\'e Allan
M\'ethot, Haran Pilpel | No nonlocal box is universal | Additions to the acknowledgements section | null | 10.1063/1.2767538 | null | quant-ph | null | We show that standard nonlocal boxes, also known as Popescu-Rohrlich
machines, are not sufficient to simulate any nonlocal correlations that do not
allow signalling. This was known in the multipartite scenario, but we extend
the result to the bipartite case. We then generalize this result further by
showing that no finite set containing any finite-output-alphabet nonlocal boxes
can be a universal set for nonlocality.
| [
{
"version": "v1",
"created": "Fri, 19 Jan 2007 17:02:52 GMT"
},
{
"version": "v2",
"created": "Sun, 25 Feb 2007 03:58:05 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Dupuis",
"Frédéric",
""
],
[
"Gisin",
"Nicolas",
""
],
[
"Hassidim",
"Avinatan",
""
],
[
"Méthot",
"André Allan",
""
],
[
"Pilpel",
"Haran",
""
]
]
|
quant-ph/0701143 | Valerio Cappellini Dr. | Valerio Cappellini (1 and 2), Hans-Juergen Sommers (3) and Karol
Zyczkowski (1 and 4) ((1) Centrum Fizyki Teoretycznej, Polska Akademia Nauk,
Warszawa, Poland, (2) "Mark Kac" Complex Systems Research Centre, Uniwersytet
Jagiellonski, Krakow, Poland, (3) Fachbereich Physik, Universitat
Duisburg-Essen, Duisburg, Germany, (4) Instytut Fizyki im. Smoluchowskiego,
Uniwersytet Jagiellonski, Krakow, Poland) | Subnormalized states and trace-nonincreasing maps | LaTeX, 21 pages, 4 Encapsuled PostScript figures, 1 table | J. Math. Phys. 48(5), 052110 (2007) | 10.1063/1.2738359 | null | quant-ph math-ph math.MP | null | We investigate the set of completely positive, trace-nonincreasing linear
maps acting on the set M_N of mixed quantum states of size N. Extremal point of
this set of maps are characterized and its volume with respect to the
Hilbert-Schmidt (Euclidean) measure is computed explicitly for an arbitrary N.
The spectra of partially reduced rescaled dynamical matrices associated with
trace-nonincreasing completely positive maps belong to the N-cube inscribed in
the set of subnormalized states of size N. As a by-product we derive the
measure in M_N induced by partial trace of mixed quantum states distributed
uniformly with respect to HS-measure in $M_{N^2}$.
| [
{
"version": "v1",
"created": "Fri, 19 Jan 2007 17:42:33 GMT"
},
{
"version": "v2",
"created": "Fri, 1 Jun 2007 12:17:38 GMT"
}
]
| 2007-06-13T00:00:00 | [
[
"Cappellini",
"Valerio",
"",
"1 and 2"
],
[
"Sommers",
"Hans-Juergen",
"",
"1 and 4"
],
[
"Zyczkowski",
"Karol",
"",
"1 and 4"
]
]
|
quant-ph/0701144 | M. V. Panduranga Rao | M.V. Panduranga Rao, V. Vinay | Quantum Finite Automata and Weighted Automata | 10 pages, Preliminary version appears in the Proceedings of
ACiD-2005, Texts in Algorithmics series of KCL publications, pp. 123-134,
2005 | null | null | null | quant-ph | null | Quantum finite automata derive their strength by exploiting interference in
complex valued probability amplitudes. Of particular interest is the 2-way
model of Ambainis and Watrous that has both quantum and classical states
(2QCFA) [A. Ambainis and J. Watrous, Two-way finite automata with quantum and
classical state, Theoretical Computer Science, 287(1), pp. 299-311, 2002],
since it combines the advantage of the power of interference in a
constant-sized quantum system with a 2-way head.
This paper is a step towards finding the least powerful model which is purely
classical and can mimic the dynamics of quantum phase. We consider weighted
automata with the Cortes-Mohri definition of language recognition [C. Cortes
and M. Mohri, Context-Free Recognition with Weighted Automata, Grammars 3(2/3),
pp. 133-150, 2000] as a candidate model for simulating 2QCFA.
Given any 2QCFA that (i) uses the accept-reject-continue observable, (ii)
recognizes a language with one-sided error and (iii) the entries of whose
unitary matrices are algebraic complex numbers, we show a method of
constructing a weighted automaton over $\mathbb{C}$ that simulates it
efficiently.
| [
{
"version": "v1",
"created": "Sat, 20 Jan 2007 09:33:04 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Rao",
"M. V. Panduranga",
""
],
[
"Vinay",
"V.",
""
]
]
|
quant-ph/0701145 | Juan Carlos Garc\'ia Escart\'in | Juan Carlos Garcia-Escartin and Pedro Chamorro-Posada | Quantum Multiplexing for Quantum Computer Networks | 14 pages, 8 figures | null | null | null | quant-ph | null | In communication networks many different channels must share a limited amount
of resources. In order to allow for multiple simultaneous communications,
multiple access techniques are routinely employed. With quantum communication,
it is possible to share a new kind of resource. All of the system channels can
be accommodated into a single channel in a larger Hilbert space. In the scheme,
a single line combines the information of all the users, and, at the receiver,
the original quantum channels are recovered. The given
multiplexer/demultiplexer circuit can perform this n qubits to qudit
transformation. Connections with superdense coding and classical multiple
access schemes are discussed.
| [
{
"version": "v1",
"created": "Mon, 22 Jan 2007 07:56:26 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Garcia-Escartin",
"Juan Carlos",
""
],
[
"Chamorro-Posada",
"Pedro",
""
]
]
|
quant-ph/0701146 | Xinwei Zha | Xin-Wei Zha, Hai-Yang Song | Non-EPR pairs quantum channel for teleporting an arbitrary two-qubit
state | null | Physics Letters A 369(2007)377 | 10.1016/j.physleta.2007.05.001 | null | quant-ph | null | Recently, Yeo and Chua [Phys. have given an explicit protocol for faithfully
teleporting an arbitrary two-qubit state via a genuine four-qubit entangled
state, which is not reducible to a pair of Bell states. Here, we present a
transformation operator to give the criterion of for faithfully teleporting
arbitrary two-qubit states. The theoretical explanations of some quantum
channels are given by transformation operators. Furthermore, a new four-qubit
entangled state quantum channel is presented.
| [
{
"version": "v1",
"created": "Sat, 20 Jan 2007 13:29:39 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Zha",
"Xin-Wei",
""
],
[
"Song",
"Hai-Yang",
""
]
]
|
quant-ph/0701147 | M. V. Panduranga Rao | M.V. Panduranga Rao | Bounding Run-Times of Local Adiabatic Algorithms | 11 pages | null | null | null | quant-ph | null | A common trick for designing faster quantum adiabatic algorithms is to apply
the adiabaticity condition locally at every instant. However it is often
difficult to determine the instantaneous gap between the lowest two
eigenvalues, which is an essential ingredient in the adiabaticity condition. In
this paper we present a simple linear algebraic technique for obtaining a lower
bound on the instantaneous gap even in such a situation. As an illustration, we
investigate the adiabatic unordered search of van Dam et al. (How powerful is
adiabatic quantum computation? Proc. IEEE FOCS, pp. 279-287, 2001) and Roland
and Cerf (Physical Review A 65, 042308, 2002) when the non-zero entries of the
diagonal final Hamiltonian are perturbed by a polynomial (in $\log N$, where
$N$ is the length of the unordered list) amount. We use our technique to derive
a bound on the running time of a local adiabatic schedule in terms of the
minimum gap between the lowest two eigenvalues.
| [
{
"version": "v1",
"created": "Sat, 20 Jan 2007 13:57:57 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Rao",
"M. V. Panduranga",
""
]
]
|
quant-ph/0701148 | Ivette Fuentes-Guridi | I. Fuentes-Schuller, P. Barberis-Blostein | Inelastic collisions in an exactly solvable two-mode Bose-Einstein
Condensate | null | Phys. Rev. A 78, 013641 (2008) | 10.1103/PhysRevA.78.013641 | null | quant-ph cond-mat.mes-hall | null | Inelastic collisions occur in Bose-Einstein condensates, in some cases,
producing particle loss in the system. Nevertheless, these processes have not
been studied in the case when particles do not escape the trap. We show that
such inelastic processes are relevant in quantum properties of the system such
as the evolution of the relative population, the self trapping effect and the
probability distribution of particles. Moreover, including inelastic terms in
the model of the two-mode condensate allows for an exact analytical solution.
Using this solution, we show that collisions favor the generation of
entanglement between the modes of the condensate as long as the collision rate
does not exceed the natural frequency of the system.
| [
{
"version": "v1",
"created": "Sun, 21 Jan 2007 04:48:45 GMT"
}
]
| 2008-09-30T00:00:00 | [
[
"Fuentes-Schuller",
"I.",
""
],
[
"Barberis-Blostein",
"P.",
""
]
]
|
quant-ph/0701149 | Dong Yang | Dong Yang, Michal Horodecki, and Z. D. Wang | Conditional Entanglement | New version, a short one submitted | null | null | null | quant-ph | null | Based on the ideas of {\it quantum extension} and {\it quantum conditioning},
we propose a generic approach to construct a new kind of entanglement measures
called {\it conditional entanglement}. The new measures, built from the known
entanglement measures, are convex, automatically {\it super-additive}, and even
smaller than the regularized versions of the generating measures. More
importantly, new measures can also be built directly from measures of
correlations, enabling us to introduce an {\it additive} measure and generalize
it to a multipartite entanglement measure.
| [
{
"version": "v1",
"created": "Sun, 21 Jan 2007 14:45:27 GMT"
},
{
"version": "v2",
"created": "Sun, 4 Feb 2007 13:13:22 GMT"
},
{
"version": "v3",
"created": "Wed, 1 Aug 2007 14:17:08 GMT"
}
]
| 2007-08-01T00:00:00 | [
[
"Yang",
"Dong",
""
],
[
"Horodecki",
"Michal",
""
],
[
"Wang",
"Z. D.",
""
]
]
|
quant-ph/0701150 | Aurel Gabris | A. Gabris, T. Kiss and I. Jex | Scattering quantum random-walk search with errors | 10 pages, 10 figures. Two figures added for clarity, also made
improvements to the text | Phys. Rev. A 76, 062315 (2007) | 10.1103/PhysRevA.76.062315 | null | quant-ph | null | We analyze the realization of a quantum-walk search algorithm in a passive,
linear optical network. The specific model enables us to consider the effect of
realistic sources of noise and losses on the search efficiency. Photon loss
uniform in all directions is shown to lead to the rescaling of search time.
Deviation from directional uniformity leads to the enhancement of the search
efficiency compared to uniform loss with the same average. In certain cases
even increasing loss in some of the directions can improve search efficiency.
We show that while we approach the classical limit of the general search
algorithm by introducing random phase fluctuations, its utility for searching
is lost. Using numerical methods, we found that for static phase errors the
averaged search efficiency displays a damped oscillatory behaviour that
asymptotically tends to a non-zero value.
| [
{
"version": "v1",
"created": "Sun, 21 Jan 2007 17:24:41 GMT"
},
{
"version": "v2",
"created": "Thu, 24 May 2007 14:28:53 GMT"
},
{
"version": "v3",
"created": "Thu, 27 Sep 2007 14:05:10 GMT"
}
]
| 2008-02-04T00:00:00 | [
[
"Gabris",
"A.",
""
],
[
"Kiss",
"T.",
""
],
[
"Jex",
"I.",
""
]
]
|
quant-ph/0701151 | Stefan Yoshi Buhmann | Stefan Yoshi Buhmann and Dirk-Gunnar Welsch | Casimir-Polder forces on excited atoms in the strong atom-field coupling
regime | 16 pages, 2 figures, extended version | Physical Review A 77 (1), 012110 (2008) | 10.1103/PhysRevA.77.012110 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Based on macroscopic quantum electrodynamics in linear media, we develop a
general theory of the resonant Casimir-Polder force on an excited two-level
atom in the presence of arbitrary linear bodies, with special emphasis on the
strong-coupling regime where reabsorption of an emitted photon can give rise to
(vacuum) Rabi oscillations. We first derive a simple time-independent
expression for the force by using a dressed-state approximation. For initially
single-quantum excited atom-field systems we then study the dynamics of the
force by starting from the Lorentz force and evaluating its average as a
function of time. For strong atom-field coupling, we find that the force may
undergo damped Rabi oscillations. The damping is due to the decay of both the
atomic excitation and the field excitation, and both amplitude and mean value
of the oscillations depend on the chosen initial state.
| [
{
"version": "v1",
"created": "Sun, 21 Jan 2007 18:49:42 GMT"
},
{
"version": "v2",
"created": "Thu, 14 Aug 2008 11:05:50 GMT"
}
]
| 2008-08-14T00:00:00 | [
[
"Buhmann",
"Stefan Yoshi",
""
],
[
"Welsch",
"Dirk-Gunnar",
""
]
]
|
quant-ph/0701152 | Daniel Reitzner | Daniel Reitzner | Comment on Afshar's expriments | 2 pages, 3 figures | null | null | null | quant-ph | null | Results of the experiments carried out in [Shahriar S. Afshar, Proc. SPIE bf
5866 (2005) 229-244] and [Shahriar S. Afshar, AIP Cof. Proc. 810, (2006)
294-299] are reviewed and their interpretation by the authors is questioned.
Arguments are supported by numerical simulations.
| [
{
"version": "v1",
"created": "Mon, 22 Jan 2007 06:59:04 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Reitzner",
"Daniel",
""
]
]
|
quant-ph/0701153 | Igor Ryabtsev | I.I.Ryabtsev, D.B.Tretyakov, I.I.Beterov, and V.M.Entin | Effect of finite detection efficiency on the observation of the
dipole-dipole interaction of a few Rydberg atoms | 10 pages, 4 figures; equations 8,9,18,19,23,26-31, figures 3 and
4(d), and measurements revised in version 3 | Phys. Rev. A 76 (2007) 012722 | 10.1103/PhysRevA.76.012722 | null | quant-ph cond-mat.mes-hall physics.atom-ph | null | We have developed a simple analytical model describing multi-atom signals
that are measured in experiments on dipole-dipole interaction at resonant
collisions of a few Rydberg atoms. It has been shown that finite efficiency of
the selective field-ionization detector leads to the mixing up of the spectra
of resonant collisions registered for various numbers of Rydberg atoms. The
formulas which help to estimate an appropriate mean Rydberg atom number for a
given detection efficiency are presented. We have found that a measurement of
the relation between the amplitudes of collisional resonances observed in the
one- and two-atom signals provides a straightforward determination of the
absolute detection efficiency and mean Rydberg atom number. We also performed a
testing experiment on resonant collisions in a small excitation volume of a
sodium atomic beam. The resonances observed for 1 to 4 detected Rydberg atoms
have been analyzed and compared with theory.
| [
{
"version": "v1",
"created": "Mon, 22 Jan 2007 08:35:05 GMT"
},
{
"version": "v2",
"created": "Mon, 4 Jun 2007 07:40:19 GMT"
},
{
"version": "v3",
"created": "Tue, 2 Oct 2007 02:56:34 GMT"
}
]
| 2007-10-02T00:00:00 | [
[
"Ryabtsev",
"I. I.",
""
],
[
"Tretyakov",
"D. B.",
""
],
[
"Beterov",
"I. I.",
""
],
[
"Entin",
"V. M.",
""
]
]
|
quant-ph/0701154 | Bernhard Meister | Bernhard K. Meister | An Extension of the Wigner-Araki-Yanase Theorem to Multiplicative
Conserved Quantities | To appear in Proceedings of QCMC 2006, Tsukuba; Final Version | null | null | null | quant-ph | null | An extension of the Wigner-Araki-Yanase theorem to multiplicative conserved
quantities is presented and approximate versions of the theorem are discussed.
| [
{
"version": "v1",
"created": "Mon, 22 Jan 2007 09:02:44 GMT"
},
{
"version": "v2",
"created": "Tue, 31 Jul 2007 06:13:21 GMT"
}
]
| 2007-07-31T00:00:00 | [
[
"Meister",
"Bernhard K.",
""
]
]
|
quant-ph/0701155 | Ramazan Sever | Ozlem Yesiltas and Ramazan Sever | Exponential Type Complex and non-Hermitian Potentials within Quantum
Hamilton-Jacobi Formalism | 16 pages | J. Math. Chem. 43, 921(2007) | null | null | quant-ph | null | PT-/non-PT-symmetric and non-Hermitian deformed Morse and Poschl-Teller
potentials are studied first time by quantum Hamilton-Jacobi approach. Energy
eigenvalues and eigenfunctions are obtained by solving quantum Hamilton-Jacobi
equation.
| [
{
"version": "v1",
"created": "Mon, 22 Jan 2007 10:53:41 GMT"
}
]
| 2008-07-15T00:00:00 | [
[
"Yesiltas",
"Ozlem",
""
],
[
"Sever",
"Ramazan",
""
]
]
|
quant-ph/0701156 | Minh Dung Dang | Minh-Dung Dang and Patrick Bellot | MLC No-go Theorems: Reinterpretation and Extension | 25 pages, revtex4 (prb, onecollumn), co-author added | null | null | null | quant-ph | null | In this article, we are interested in the physical model of general quantum
protocols implementing secure two-party computations in the light of Mayers'
and Lo's & Chau's no-go theorems of bit commitment and oblivious transfer. In
contrast to the commonly adobted quantum pure two-party model in the literature
where classical communication is normally ignored, we propose an alternative
interpretation for the purification of classical communication in two-party
protocols by introducing a quantum third party for the classical channel. This
interpretation leads to a global three-party model, involving Alice's and Bob's
machines and the environment coupled to the macroscopic channel, using the
decoherence scheme in quantum measurements. This model could give a more
general view on the concealing/binding trade-off of quantum bit commitment
protocols.
Inspired from this three-party interpretation, we extend the no-go theorems
for denying some classes of two-party protocols having access to some
particular quantum trusted third-parties, known as quantum two-party oracles.
The extension implies that a quantum protocol for implementing secure two-party
computations musts have access to a trusted third-party which erases
information and thus makes dissipation of heat to the environment.
| [
{
"version": "v1",
"created": "Mon, 22 Jan 2007 11:23:54 GMT"
},
{
"version": "v2",
"created": "Thu, 24 May 2007 17:59:07 GMT"
},
{
"version": "v3",
"created": "Fri, 25 May 2007 00:46:31 GMT"
},
{
"version": "v4",
"created": "Tue, 29 May 2007 14:56:03 GMT"
},
{
"version": "v5",
"created": "Fri, 21 Mar 2008 14:12:10 GMT"
}
]
| 2008-03-21T00:00:00 | [
[
"Dang",
"Minh-Dung",
""
],
[
"Bellot",
"Patrick",
""
]
]
|
quant-ph/0701157 | Roberto Floreanini | S. Anderloni, F. Benatti and R. Floreanini | Redfield reduced dynamics and entanglement | 10 pages, 1 figure | null | 10.1088/1751-8113/40/7/013 | null | quant-ph | null | In phenomenological applications the time evolution of subsystems immersed in
an external environment are sometimes described by Markovian semigroups of
Redfield type that result non-positive: the appearence of negative
probabilities is avoided by restricting the admissible initial conditions to
those states that remain positive under the action of the dynamics. We show
that this often adopted procedure may lead to physical inconsistencies in
presence of entanglement.
| [
{
"version": "v1",
"created": "Mon, 22 Jan 2007 11:55:00 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Anderloni",
"S.",
""
],
[
"Benatti",
"F.",
""
],
[
"Floreanini",
"R.",
""
]
]
|
quant-ph/0701158 | Luca Pezz\'e | L. Pezze (BEC-CNR-Infm), A. Smerzi (BEC-CNR-Infm), G. Khoury (UCSB),
J. F. Hodelin (UCSB) and D. Bouwmeester (UCSB) | Phase detection at the quantum limit with multi-photon Mach-Zehnder
interferometry | 4 pages, 5 figures replaced fig. 1 to correct graphics bug | null | 10.1103/PhysRevLett.99.223602 | null | quant-ph cond-mat.other cond-mat.stat-mech | null | We study a Mach-Zehnder interferometer fed by a coherent state in one input
port and vacuum in the other. We explore a Bayesian phase estimation strategy
to demonstrate that it is possible to achieve the standard quantum limit
independently from the true value of the phase shift and specific assumptions
on the noise of the interferometer. We have been able to implement the protocol
using parallel operation of two photon-number-resolving detectors and
multiphoton coincidence logic electronics at the output ports of a
weakly-illuminated Mach-Zehnder interferometer. This protocol is unbiased and
saturates the Cramer-Rao phase uncertainty bound and, therefore, is an optimal
phase estimation strategy.
| [
{
"version": "v1",
"created": "Mon, 22 Jan 2007 12:41:35 GMT"
},
{
"version": "v2",
"created": "Fri, 26 Jan 2007 18:56:51 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Pezze",
"L.",
"",
"BEC-CNR-Infm"
],
[
"Smerzi",
"A.",
"",
"BEC-CNR-Infm"
],
[
"Khoury",
"G.",
"",
"UCSB"
],
[
"Hodelin",
"J. F.",
"",
"UCSB"
],
[
"Bouwmeester",
"D.",
"",
"UCSB"
]
]
|
quant-ph/0701159 | Ahmed Bouda | A. Bouda and A. Mohamed Meziane | The Three-Dimensional Quantum Hamilton-Jacobi Equation and Microstates | 16 pages, no figures | Int. J. Theo. Phys. 45 (2006) 1323 | null | null | quant-ph hep-th | null | In a stationary case and for any potential, we solve the three-dimensional
quantum Hamilton-Jacobi equation in terms of the solutions of the corresponding
Schrodinger equation. Then, in the case of separated variables, by requiring
that the conjugate momentum be invariant under any linear transformation of the
solutions of the Schrodinger equation used in the reduced action, we clearly
identify the integration constants successively in one, two and three
dimensions. In each of these cases, we analytically establish that the quantum
Hamilton-Jacobi equation describes microstates not detected by the Schrodinger
equation in the real wave function case.
| [
{
"version": "v1",
"created": "Mon, 22 Jan 2007 12:39:07 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Bouda",
"A.",
""
],
[
"Meziane",
"A. Mohamed",
""
]
]
|
quant-ph/0701160 | Vahid Karimipour | M. Asoudeh, V. Karimipour, A. Sadrolashrafi | Matrix product states and exactly solvable spin 1/2 Heisenberg chains
with nearest neighbor interactions | 4 pages, RevTex, references added, improved presentation, typos fixed | Phys. Rev. A 76, 012320 (2007) | 10.1103/PhysRevA.76.012320 | null | quant-ph cond-mat.str-el | null | Using the matrix product formalism, we introduce a two parameter family of
exactly solvable $xyz$ spin 1/2 Heisenberg chains in magnetic field (with
nearest neighbor interactions) and calculate the ground state and correlation
functions in compact form. The ground state has a very interesting property:
all the pairs of spins are equally entangled with each other. Therefore it is
possible to engineer long-range entanglement in experimentally realizable spin
systems on the one hand and study more closely quantum phase transition in such
systems on the other.
| [
{
"version": "v1",
"created": "Mon, 22 Jan 2007 13:55:48 GMT"
},
{
"version": "v2",
"created": "Tue, 23 Jan 2007 17:03:15 GMT"
},
{
"version": "v3",
"created": "Thu, 25 Jan 2007 05:53:43 GMT"
},
{
"version": "v4",
"created": "Fri, 26 Jan 2007 08:26:31 GMT"
},
{
"version": "v5",
"created": "Mon, 19 Mar 2007 18:13:03 GMT"
}
]
| 2013-05-29T00:00:00 | [
[
"Asoudeh",
"M.",
""
],
[
"Karimipour",
"V.",
""
],
[
"Sadrolashrafi",
"A.",
""
]
]
|
quant-ph/0701161 | Alexandre Zagoskin | A. M. Zagoskin, S. Savel'ev, and Franco Nori | Modeling an adiabatic quantum computer | 8 pages 2 figures | Phys. Rev. Lett. 98, 120503 (2007) | null | null | quant-ph cond-mat.stat-mech | null | We map adiabatic quantum evolution on the classical Hamiltonian dynamics of a
1D gas (Pechukas gas) and simulate the latter numerically. This approach turns
out to be both insightful and numerically efficient, as seen from our example
of a CNOT gate simulation. For a general class of Hamiltonians we show that the
escape probability from the initial state scales no faster than
|\dot{\lambda}|^{\gamma}, where |\dot{\lambda}| is the adiabaticity parameter.
The scaling exponent for the escape probability is \gamma = 1/2 for all levels,
except the edge (bottom and top) ones, where \gamma <~1/3. In principle, our
method can solve arbitrarily large adiabatic quantum Hamiltonians.
| [
{
"version": "v1",
"created": "Mon, 22 Jan 2007 19:00:20 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Zagoskin",
"A. M.",
""
],
[
"Savel'ev",
"S.",
""
],
[
"Nori",
"Franco",
""
]
]
|
quant-ph/0701162 | Alexandre Dodonov V | A. V. Dodonov, S. S. Mizrahi and V. V. Dodonov | How to check the one-count operator experimentally | 5 pages, 4 figures. New references and discussion added | null | null | null | quant-ph | null | We propose an experimental scheme to probe the form of one-count operation
used in the theory of continuous photodetection in cavities. Two main steps
are: 1) an absorption of a single photon by an atom passing through a high-Q
cavity containing electromagnetic field in a thermal or coherent state, 2) a
subsequent measurement of the photon statistics in the new field state arising
after the photon absorption. Then comparing the probabilities of finding 0 and
1 photons in the initial and final states of the field, one can make
conclusions on the form of the one-count operation. This method can be readily
applied in the microwave cavity QED with present technology.
| [
{
"version": "v1",
"created": "Mon, 22 Jan 2007 19:08:40 GMT"
},
{
"version": "v2",
"created": "Wed, 14 Mar 2007 23:17:37 GMT"
},
{
"version": "v3",
"created": "Fri, 16 Mar 2007 09:45:20 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Dodonov",
"A. V.",
""
],
[
"Mizrahi",
"S. S.",
""
],
[
"Dodonov",
"V. V.",
""
]
]
|
quant-ph/0701163 | Daegene Song | Daegene Song | Wave-Particle Duality in the Negative Information Sea | 4 pages, 3 figures | null | null | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Quantum theory reveals astonishing and counterintuitive phenomena not found
in classical physics, such as wave-particle duality, where entities like
electrons and photons exhibit both wave-like and particle-like behaviors. In
this paper, we leverage advancements in quantum information science to gain new
insights into this phenomenon. We specifically examine negative conditional
entropy in quantum entanglement, where the selection of the measurement basis
appears to ripple backward in time, akin to Dirac's model of an infinite sea of
negative energy states filled with electrons, where holes in this sea appear as
positrons. We propose that an observer's knowledge of the measurement choice,
analogous to a hole in the negative information sea, corresponds to the wave
aspect of the system, while the classical outcome aligns with its particle
nature. This exploration of the relationship between microscopic quantum
phenomena and macroscopic observations offers new perspectives on the
mind-matter duality.
| [
{
"version": "v1",
"created": "Mon, 22 Jan 2007 20:05:32 GMT"
},
{
"version": "v2",
"created": "Thu, 22 Oct 2015 23:34:16 GMT"
},
{
"version": "v3",
"created": "Mon, 7 Sep 2020 01:25:45 GMT"
},
{
"version": "v4",
"created": "Tue, 20 Sep 2022 01:26:29 GMT"
},
{
"version": "v5",
"created": "Tue, 2 Jul 2024 06:33:07 GMT"
}
]
| 2024-07-03T00:00:00 | [
[
"Song",
"Daegene",
""
]
]
|
quant-ph/0701164 | Lu Deng | K.J. Jiang, L. Deng, and M.G. Payne | Superluminal propagation of an optical pulse in a Doppler broadened
three-state, single channel active Raman gain medium | 4 pages, 3 figures | null | 10.1103/PhysRevA.76.033819 | null | quant-ph | null | Using a single channel active Raman gain medium we show a $(220\pm 20)$ns
advance time for an optical pulse of $\tau_{FWHM}=15.4 \mu$s propagating
through a 10 cm medium, a lead time that is comparable to what was reported
previously. In addition, we have verified experimentally all the features
associated with this single channel Raman gain system. Our results show that
the reported gain-assisted superluminal propagation should not be attributed to
the interference between the two frequencies of the pump field.
| [
{
"version": "v1",
"created": "Mon, 22 Jan 2007 20:07:16 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Jiang",
"K. J.",
""
],
[
"Deng",
"L.",
""
],
[
"Payne",
"M. G.",
""
]
]
|
quant-ph/0701165 | Matthew Testolin | M. J. Testolin, C. D. Hill, C. J. Wellard, and L. C. L. Hollenberg | A precise CNOT gate in the presence of large fabrication induced
variations of the exchange interaction strength | 9 pages, 8 figures | null | 10.1103/PhysRevA.76.012302 | null | quant-ph cond-mat.mes-hall | null | We demonstrate how using two-qubit composite rotations a high fidelity
controlled-NOT (CNOT) gate can be constructed, even when the strength of the
interaction between qubits is not accurately known. We focus on the exchange
interaction oscillation in silicon based solid-state architectures with a
Heisenberg Hamiltonian. This method easily applies to a general two-qubit
Hamiltonian. We show how the robust CNOT gate can achieve a very high fidelity
when a single application of the composite rotations is combined with a modest
level of Hamiltonian characterisation. Operating the robust CNOT gate in a
suitably characterised system means concatenation of the composite pulse is
unnecessary, hence reducing operation time, and ensuring the gate operates
below the threshold required for fault-tolerant quantum computation.
| [
{
"version": "v1",
"created": "Tue, 23 Jan 2007 03:49:47 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Testolin",
"M. J.",
""
],
[
"Hill",
"C. D.",
""
],
[
"Wellard",
"C. J.",
""
],
[
"Hollenberg",
"L. C. L.",
""
]
]
|
quant-ph/0701166 | Jian-Zu Zhang | Jian-Zu Zhang | A Constraint between Noncommutative Parameters of Quantum Theories in
Noncommutative Space | 13 pages | null | null | null | quant-ph | null | In two-dimensional noncommutive space for the case of both position -
position and momentum - momentum noncommuting, a constraint between
noncommutative parameters is investigated. The related topic of guaranteeing
Bose - Einstein statistics in noncommutive space in the general case are
elucidated: Bose - Einstein statistics is guaranteed by the deformed Heisenberg
- Weyl algebra itself, independent of dynamics. A special character of a
dynamical system is represented by a constraint between noncommutative
parameters. The general feature of the constraint for any system is a direct
proportionality between noncommutative parameters with a proportional
coefficient depending on characteristic parameters of the system under study.
The constraint for a harmonic oscillator is illustrated.
| [
{
"version": "v1",
"created": "Tue, 23 Jan 2007 11:31:44 GMT"
},
{
"version": "v2",
"created": "Thu, 12 Apr 2007 08:07:42 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Zhang",
"Jian-Zu",
""
]
]
|
quant-ph/0701167 | Guillem Sagu\'e | G. Sagu\'e, E. Vetsch, W. Alt, D. Meschede and A. Rauschenbeutel | Cold Atom Physics Using Ultra-Thin Optical Fibers: Light-Induced Dipole
Forces and Surface Interactions | 4 pages, 4 figures | PRL 99, 163602 (2007) | 10.1103/PhysRevLett.99.163602 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The strong evanescent field around ultra-thin unclad optical fibers bears a
high potential for detecting, trapping, and manipulating cold atoms.
Introducing such a fiber into a cold atom cloud, we investigate the interaction
of a small number of cold Caesium atoms with the guided fiber mode and with the
fiber surface. Using high resolution spectroscopy, we observe and analyze
light-induced dipole forces, van der Waals interaction, and a significant
enhancement of the spontaneous emission rate of the atoms. The latter can be
assigned to the modification of the vacuum modes by the fiber.
| [
{
"version": "v1",
"created": "Tue, 23 Jan 2007 13:39:22 GMT"
},
{
"version": "v2",
"created": "Tue, 2 Oct 2007 12:13:46 GMT"
},
{
"version": "v3",
"created": "Tue, 2 Oct 2007 20:59:20 GMT"
},
{
"version": "v4",
"created": "Wed, 4 Feb 2009 12:27:37 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Sagué",
"G.",
""
],
[
"Vetsch",
"E.",
""
],
[
"Alt",
"W.",
""
],
[
"Meschede",
"D.",
""
],
[
"Rauschenbeutel",
"A.",
""
]
]
|
quant-ph/0701168 | Romain All\'eaume | Romain All\'eaume, Cyril Branciard, Jan Bouda, Thierry Debuisschert,
Mehrdad Dianati, Nicolas Gisin, Mark Godfrey, Philippe Grangier, Thomas
Langer, Norbert Lutkenhaus, Christian Monyk, Philippe Painchault, Momtchil
Peev, Andreas Poppe, Thomas Pornin, John Rarity, Renato Renner, Gregoire
Ribordy, Michel Riguidel, Louis Salvail, Andrew Shields, Harald Weinfurter,
Anton Zeilinger | Using quantum key distribution for cryptographic purposes: a survey | Revised version of the SECOQC White Paper. Published in the special
issue on QKD of TCS, Theoretical Computer Science (2014), pp. 62-81 | Theoretical Computer Science, 560 (2014), pp. 62-81 | null | null | quant-ph cs.CR cs.IT math.IT | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The appealing feature of quantum key distribution (QKD), from a cryptographic
viewpoint, is the ability to prove the information-theoretic security (ITS) of
the established keys. As a key establishment primitive, QKD however does not
provide a standalone security service in its own: the secret keys established
by QKD are in general then used by a subsequent cryptographic applications for
which the requirements, the context of use and the security properties can
vary. It is therefore important, in the perspective of integrating QKD in
security infrastructures, to analyze how QKD can be combined with other
cryptographic primitives. The purpose of this survey article, which is mostly
centered on European research results, is to contribute to such an analysis. We
first review and compare the properties of the existing key establishment
techniques, QKD being one of them. We then study more specifically two generic
scenarios related to the practical use of QKD in cryptographic infrastructures:
1) using QKD as a key renewal technique for a symmetric cipher over a
point-to-point link; 2) using QKD in a network containing many users with the
objective of offering any-to-any key establishment service. We discuss the
constraints as well as the potential interest of using QKD in these contexts.
We finally give an overview of challenges relative to the development of QKD
technology that also constitute potential avenues for cryptographic research.
| [
{
"version": "v1",
"created": "Tue, 23 Jan 2007 14:25:32 GMT"
},
{
"version": "v2",
"created": "Wed, 3 Dec 2014 18:07:36 GMT"
},
{
"version": "v3",
"created": "Thu, 4 Dec 2014 23:28:28 GMT"
}
]
| 2014-12-10T00:00:00 | [
[
"Alléaume",
"Romain",
""
],
[
"Branciard",
"Cyril",
""
],
[
"Bouda",
"Jan",
""
],
[
"Debuisschert",
"Thierry",
""
],
[
"Dianati",
"Mehrdad",
""
],
[
"Gisin",
"Nicolas",
""
],
[
"Godfrey",
"Mark",
""
],
[
"Grangier",
"Philippe",
""
],
[
"Langer",
"Thomas",
""
],
[
"Lutkenhaus",
"Norbert",
""
],
[
"Monyk",
"Christian",
""
],
[
"Painchault",
"Philippe",
""
],
[
"Peev",
"Momtchil",
""
],
[
"Poppe",
"Andreas",
""
],
[
"Pornin",
"Thomas",
""
],
[
"Rarity",
"John",
""
],
[
"Renner",
"Renato",
""
],
[
"Ribordy",
"Gregoire",
""
],
[
"Riguidel",
"Michel",
""
],
[
"Salvail",
"Louis",
""
],
[
"Shields",
"Andrew",
""
],
[
"Weinfurter",
"Harald",
""
],
[
"Zeilinger",
"Anton",
""
]
]
|
quant-ph/0701169 | Ignacio Garcia-Mata | Ignacio Garcia-Mata, Klaus M. Frahm, and Dima L. Shepelyansky
(UPS-CNRS, Toulouse) | Effects of imperfections for Shor's factorization algorithm | 10 pages, 10 figures, 1 table. Added references and new data. Erratum
added as appendix. 1 Figure and 1 Table added. Research is available at
http://www.quantware.ups-tlse.fr/ | Phys. Rev. A 75, 052311 (2007) | 10.1103/PhysRevA.75.052311 | null | quant-ph | null | We study effects of imperfections induced by residual couplings between
qubits on the accuracy of Shor's algorithm using numerical simulations of
realistic quantum computations with up to 30 qubits. The factoring of numbers
up to N=943 show that the width of peaks, which frequencies allow to determine
the factors, grow exponentially with the number of qubits. However, the
algorithm remains operational up to a critical coupling strength $\epsilon_c$
which drops only polynomially with $\log_2 N$. The numerical dependence of
$\epsilon_c$ on $\log_2 N$ is explained by analytical estimates that allows to
obtain the scaling for functionality of Shor's algorithm on realistic quantum
computers with a large number of qubits.
| [
{
"version": "v1",
"created": "Tue, 23 Jan 2007 14:39:31 GMT"
},
{
"version": "v2",
"created": "Tue, 3 Apr 2007 12:23:38 GMT"
},
{
"version": "v3",
"created": "Thu, 6 Sep 2007 14:11:59 GMT"
}
]
| 2007-09-06T00:00:00 | [
[
"Garcia-Mata",
"Ignacio",
"",
"UPS-CNRS, Toulouse"
],
[
"Frahm",
"Klaus M.",
"",
"UPS-CNRS, Toulouse"
],
[
"Shepelyansky",
"Dima L.",
"",
"UPS-CNRS, Toulouse"
]
]
|
quant-ph/0701170 | Jung-Tsung Shen | Jung-Tsung Shen and Shanhui Fan | Strongly Correlated Two-Photon Transport in One-Dimensional Waveguide
Coupled to A Two-Level System | 12 pages. 3 figures. Accepted by Physical Review Letters | Phys. Rev. Lett. 98, 153003 (2007) | 10.1103/PhysRevLett.98.153003 | null | quant-ph | null | We show that two-photon transport is strongly correlated in one-dimensional
waveguide coupled to a two-level system. The exact S-matrix is constructed
using a generalized Bethe-Ansatz technique. We show that the scattering
eigenstates of this system include a two-photon bound state that passes through
the two-level system as a composite single particle. Also, the two-level system
can induce effective attractive or repulsive interactions in space for photons.
This general procedure can be applied to the Anderson model as well.
| [
{
"version": "v1",
"created": "Tue, 23 Jan 2007 18:21:32 GMT"
},
{
"version": "v2",
"created": "Tue, 13 Mar 2007 22:03:40 GMT"
}
]
| 2008-02-13T00:00:00 | [
[
"Shen",
"Jung-Tsung",
""
],
[
"Fan",
"Shanhui",
""
]
]
|
quant-ph/0701171 | Paola Zizzi | Paola A. Zizzi | Turning the Liar paradox into a metatheorem of Basic logic | 12 pages, 1 figure, submitted to CIE 2007. The subject of Section 4,
formerly devoted to the conclusions, has been changed, and is about a
generalized version of self-reference | null | null | null | quant-ph cs.LO math.LO | null | We show that self-reference can be formalized in Basic logic by means of the
new connective @, called "entanglement". In fact, the property of
non-idempotence of the connective @ is a metatheorem, which states that a
self-entangled sentence loses its own identity. This prevents having
self-referential paradoxes in the corresponding metalanguage. In this context,
we introduce a generalized definition of self-reference, which is needed to
deal with the multiplicative connectives of substructural logics.
| [
{
"version": "v1",
"created": "Tue, 23 Jan 2007 18:36:47 GMT"
},
{
"version": "v2",
"created": "Wed, 28 Mar 2007 11:53:27 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Zizzi",
"Paola A.",
""
]
]
|
quant-ph/0701172 | Chuanwei Zhang | Chuanwei Zhang, V.W. Scarola, and S. Das Sarma | Initializing a Quantum Register from Mott Insulator States in Optical
Lattices | 5 pages, 3 figures | Phys. Rev. A 75, 060301(R) (2007) | 10.1103/PhysRevA.75.060301 | null | quant-ph cond-mat.other | null | We propose and quantitatively develop two schemes to quickly and accurately
generate a stable initial configuration of neutral atoms in optical microtraps
by extraction from the Mott insulator state in optical lattices. We show that
thousands of atoms may be extracted and stored in the ground states of optical
microtrap arrays with one atom per trap in one operational process
demonstrating massive scalability. The failure probability during extraction in
the first scheme can be made sufficiently small (10^{-4}) to initialize a large
scale quantum register with high fidelity. A complementary faster scheme with
more extracted atoms but lower fidelity is also developed.
| [
{
"version": "v1",
"created": "Tue, 23 Jan 2007 21:06:00 GMT"
},
{
"version": "v2",
"created": "Wed, 6 Jun 2007 16:21:05 GMT"
}
]
| 2007-06-06T00:00:00 | [
[
"Zhang",
"Chuanwei",
""
],
[
"Scarola",
"V. W.",
""
],
[
"Sarma",
"S. Das",
""
]
]
|
quant-ph/0701173 | Hari Krovi | Hari Krovi and Todd A. Brun | Quantum walks on quotient graphs | 18 pages, 7 figures in EPS format | Physical Review A 75, 062332 (2007) | 10.1103/PhysRevA.75.062332 | null | quant-ph | null | A discrete-time quantum walk on a graph is the repeated application of a
unitary evolution operator to a Hilbert space corresponding to the graph. If
this unitary evolution operator has an associated group of symmetries, then for
certain initial states the walk will be confined to a subspace of the original
Hilbert space. Symmetries of the original graph, given by its automorphism
group, can be inherited by the evolution operator. We show that a quantum walk
confined to the subspace corresponding to this symmetry group can be seen as a
different quantum walk on a smaller quotient graph. We give an explicit
construction of the quotient graph for any subgroup of the automorphism group
and illustrate it with examples. The automorphisms of the quotient graph which
are inherited from the original graph are the original automorphism group
modulo the subgroup used to construct it. We then analyze the behavior of
hitting times on quotient graphs. Hitting time is the average time it takes a
walk to reach a given final vertex from a given initial vertex. It has been
shown in earlier work [Phys. Rev. A {\bf 74}, 042334 (2006)] that the hitting
time can be infinite. We give a condition which determines whether the quotient
graph has infinite hitting times given that they exist in the original graph.
We apply this condition for the examples discussed and determine which quotient
graphs have infinite hitting times. All known examples of quantum walks with
fast hitting times correspond to systems with quotient graphs much smaller than
the original graph; we conjecture that the existence of a small quotient graph
with finite hitting times is necessary for a walk to exhibit a quantum
speed-up.
| [
{
"version": "v1",
"created": "Tue, 23 Jan 2007 21:27:32 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Krovi",
"Hari",
""
],
[
"Brun",
"Todd A.",
""
]
]
|
quant-ph/0701174 | Kamil Br\'adler | Kamil Bradler | Eavesdropping of quantum communication from a non-inertial frame | accepted in PRA | null | null | null | quant-ph gr-qc | null | We introduce a relativistic version of quantum encryption protocol by
considering two inertial observers who wish to securely transmit quantum
information encoded in a free scalar quantum field state forming Minkowski
particles. In a non-relativistic setting a certain amount of shared classical
resources is necessary to perfectly encrypt the state. We show that in the case
of a uniformly accelerated eavesdropper the communicating parties need to share
(asymptotically in the limit of infinite acceleration) just half of the
classical resources.
| [
{
"version": "v1",
"created": "Wed, 24 Jan 2007 02:39:11 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Bradler",
"Kamil",
""
]
]
|
quant-ph/0701175 | Jing Zhang | Jing Zhang, Re-Bing Wu, Chun-Wen Li, Tzyh-Jong Tarn, Jian-Wu Wu | Asymptotically noise decoupling for Markovian open quantum systems | 11 pages, 10 figures | Phys. Rev. A 75, 022324 (2007) | 10.1103/PhysRevA.75.022324 | null | quant-ph | null | The noise decoupling problem is investigated for general N-level Markovian
open quantum systems. Firstly, the concept of Cartan decomposition of the Lie
algebra $su(N)$ is introduced as a tool of designing control Hamiltonians.
Next, under certain assumptions, it is shown that a part of variables of the
coherence vector of the system density matrix can be asymptotically decoupled
from the environmental noises. The resulting noise decoupling scheme is applied
to one-qubit, qutrit and two-qubit quantum systems, by which the coherence
evolution of the one-qubit and qutrit systems can always be asymptotically
preserved, while, for two-qubit systems, our findings indicate that evolution
of some variables can be preserved only for some initial states.
| [
{
"version": "v1",
"created": "Wed, 24 Jan 2007 04:22:06 GMT"
}
]
| 2009-09-30T00:00:00 | [
[
"Zhang",
"Jing",
""
],
[
"Wu",
"Re-Bing",
""
],
[
"Li",
"Chun-Wen",
""
],
[
"Tarn",
"Tzyh-Jong",
""
],
[
"Wu",
"Jian-Wu",
""
]
]
|
quant-ph/0701176 | Anne Amy | Christophe Daussy (LPL), Mickael Guinet (LPL), Anne Amy-Klein (LPL),
Khelifa Djerroud (LPL), Yves Hermier (LNE-INM CNAM), Stephan Briaudeau
(LNE-INM CNAM), Christian J. Bord\'e (LPL), Christian Chardonnet (LPL) | First direct determination of the Boltzmann constant by an optical
method | null | Physical Review Letters 98 (2007) 250801 | 10.1103/PhysRevLett.98.250801 | null | quant-ph | null | We have recorded the Doppler profile of a well-isolated rovibrational line in
the \nu2 band of 14NH3. Ammonia gas was placed in an absorption cell
thermalized by a water-ice bath. By extrapolating to zero pressure, we have
deduced the Doppler width which gives a first measurement of the Boltzmann
constant, kB, by laser spectroscopy. A relative uncertainty of 2x10-4 has been
obtained. The present determination should be significantly improved in the
near future and contribute to a new definition of the kelvin.
| [
{
"version": "v1",
"created": "Wed, 24 Jan 2007 14:02:48 GMT"
}
]
| 2016-08-14T00:00:00 | [
[
"Daussy",
"Christophe",
"",
"LPL"
],
[
"Guinet",
"Mickael",
"",
"LPL"
],
[
"Amy-Klein",
"Anne",
"",
"LPL"
],
[
"Djerroud",
"Khelifa",
"",
"LPL"
],
[
"Hermier",
"Yves",
"",
"LNE-INM CNAM"
],
[
"Briaudeau",
"Stephan",
"",
"LNE-INM CNAM"
],
[
"Bordé",
"Christian J.",
"",
"LPL"
],
[
"Chardonnet",
"Christian",
"",
"LPL"
]
]
|
quant-ph/0701177 | Brihaye Yves | Y. Brihaye, Ancilla Nininahazwe, Bhabani Prasad Mandal | PT-Symmetric, Quasi-Exactly Solvable matrix Hamiltonians | 14 pages, 1 figure, one equation corrected, results added | J.Phys.A40:13063-13074,2007 | 10.1088/1751-8113/40/43/014 | null | quant-ph hep-th | null | Matrix quasi exactly solvable operators are considered and new conditions are
determined to test whether a matrix differential operator possesses one or
several finite dimensional invariant vector spaces. New examples of $2\times
2$-matrix quasi exactly solvable operators are constructed with the emphasis
set on PT-symmetric Hamiltonians.
| [
{
"version": "v1",
"created": "Wed, 24 Jan 2007 10:08:32 GMT"
},
{
"version": "v2",
"created": "Tue, 20 Feb 2007 13:44:47 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Brihaye",
"Y.",
""
],
[
"Nininahazwe",
"Ancilla",
""
],
[
"Mandal",
"Bhabani Prasad",
""
]
]
|
quant-ph/0701178 | Bassano Vacchini | L. Lanz, B. Vacchini, O. Melsheimer | Quantum theory: the role of microsystems and macrosystems | 12 pages. For special issue of J.Phys.A, "The Quantum Universe", on
the occasion of 70th birthday of Professor Giancarlo Ghirardi | J. Phys. A: Math. Theor. 40 (2007) 3123-3140 | 10.1088/1751-8113/40/12/S14 | null | quant-ph | null | We stress the notion of statistical experiment, which is mandatory for
quantum mechanics, and recall Ludwig's foundation of quantum mechanics, which
provides the most general framework to deal with statistical experiments giving
evidence for particles. In this approach particles appear as interaction
carriers between preparation and registration apparatuses. We further briefly
point out the more modern and versatile formalism of quantum theory, stressing
the relevance of probabilistic concepts in its formulation. At last we discuss
the role of macrosystems, focusing on quantum field theory for their
description and introducing for them objective state parameters.
| [
{
"version": "v1",
"created": "Wed, 24 Jan 2007 12:32:08 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Lanz",
"L.",
""
],
[
"Vacchini",
"B.",
""
],
[
"Melsheimer",
"O.",
""
]
]
|
quant-ph/0701179 | Martin Berninger | Martin Berninger, Andr\'e Stefanov, Sarayut Deachapunya, Markus Arndt | Polarizability measurements in a molecule near-field interferometer | 4 pages, 4 figures | Phys. Rev. A 76, 013607 (2007) | 10.1103/PhysRevA.76.013607 | null | quant-ph | null | We apply near-field matter-wave interferometry to determine the absolute
scalar polarizability of the fullerenes C$_{60}$ and C$_{70}$. A key feature of
our experiment is the combination of good transmission and high spatial
resolution, gained by wide molecular beams passing through sub-micron gratings.
This allows to significantly facilitate the observation of field-dependent beam
shifts. We thus measure the polarizability to be $\alpha=88.9 \pm 0.9 \pm 5.1
\rm \AA^{3}$ for C$_{60}$ and to $\alpha = 108.5 \pm 2.0 \pm 6.2 \rm \AA^{3}$
for C$_{70}$.
| [
{
"version": "v1",
"created": "Thu, 25 Jan 2007 08:53:49 GMT"
}
]
| 2007-10-01T00:00:00 | [
[
"Berninger",
"Martin",
""
],
[
"Stefanov",
"André",
""
],
[
"Deachapunya",
"Sarayut",
""
],
[
"Arndt",
"Markus",
""
]
]
|
quant-ph/0701180 | Nataliia Cherkashyna | Constantin V. Usenko and Nataliia O. Cherkashyna | Coherent electron pair. Electromagnetic field | 18 pages, 6 figures | null | null | null | quant-ph | null | It is shown that relative coordinate and momentum of coherent electron pair
have the meaning of observables with the help of quadrupole and magnetic
moments. Distributions of quadrupole terms of scalar potential are shown. These
distributions have nonclassical properties.
| [
{
"version": "v1",
"created": "Thu, 25 Jan 2007 13:04:34 GMT"
},
{
"version": "v2",
"created": "Sat, 3 Mar 2007 16:24:22 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Usenko",
"Constantin V.",
""
],
[
"Cherkashyna",
"Nataliia O.",
""
]
]
|
quant-ph/0701181 | Johann Summhammer | Johann Summhammer | Quantum Theory as Efficient Representation of Probabilistic Information | 5 figures | null | null | null | quant-ph | null | Quantum experiments yield random data. We show that the most efficient way to
store this empirical information by a finite number of bits is by means of the
vector of square roots of observed relative frequencies. This vector has the
unique property that its dispersion becomes invariant of the underlying
probabilities, and therefore invariant of the physical parameters. This also
extends to the complex square roots, and it remains true under a unitary
transformation. This reveals quantum theory as a theory for making predictions
which are as accurate as the input information, without any statistical loss.
Our analysis also suggests that from the point of view of information a
slightly more accurate theory than quantum theory should be possible.
| [
{
"version": "v1",
"created": "Thu, 25 Jan 2007 14:01:54 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Summhammer",
"Johann",
""
]
]
|
quant-ph/0701182 | Giovanna Morigi Dr | Susanne Pielawa, Giovanna Morigi, David Vitali, Luiz Davidovich | Generation of EPR-entangled radiation through an atomic reservoir | 4 pages, 3 figures, final version, to appear in Phys. Rev. Lett | Phys. Rev. Lett. 98, 240401 (2007). | 10.1103/PhysRevLett.98.240401 | null | quant-ph cond-mat.other physics.atom-ph | null | We propose a scheme for generating two-mode squeezing in high-Q resonators
using a beam of atoms with random arrival times, which acts as a reservoir for
the field. The scheme is based on four-wave mixing processes leading to
emission into two cavity modes, which are resonant with the Rabi sidebands of
the atomic dipole transition, driven by a saturating classical field. At steady
state the cavity modes are in an Einstein-Podolski-Rosen (EPR) state, whose
degree of entanglement is controlled by the intensity and the frequency of the
transverse field. This scheme is robust against stochastic fluctuations in the
atomic beam, does not require atomic detection nor velocity selection, and can
be realized by presently available experimental setups with microwave
resonators.
| [
{
"version": "v1",
"created": "Thu, 25 Jan 2007 17:07:07 GMT"
},
{
"version": "v2",
"created": "Tue, 8 May 2007 12:20:43 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Pielawa",
"Susanne",
""
],
[
"Morigi",
"Giovanna",
""
],
[
"Vitali",
"David",
""
],
[
"Davidovich",
"Luiz",
""
]
]
|
quant-ph/0701183 | Anirban Pathak | Prakash Gupta and Anirban Pathak | Reduction of Quantum Phase Fluctuations Implies Antibunching of Photon | 9 pages Latex 2e, No figure | Phys. Lett. A (2007) Inpress | 10.1016/j.physleta.2007.01.031 | null | quant-ph | null | A clear physical meaning of the Carruthers-Nieto symmetric quantum phase
fluctuation parameter (U) has been provided in Susskind Glogower and Barnett
Pegg formalism of quantum phase and it is shown that the reduction of phase
fluctuation parameter U with respect to its coherent state value corresponds to
an antibunched state. Thus nonclassicality of a state may be manifested through
the phase fluctuation parameters. As examples, quantum phase fluctuations in
different optical processes, such as four wave mixing, six wave mixing and
second harmonic generation have been studied by using Carruthers-Nieto quantum
phase fluctuation parameters. The operators required for the calculation of
quantum phase fluctuations are expressed in closed analytical forms (up to
second order in coupling constant). It is also found that the reduction of
phase fluctuations compared to their initial values are possible in all three
cases which means nonclassical (antibunched) state exists in all these cases.
| [
{
"version": "v1",
"created": "Thu, 25 Jan 2007 19:21:53 GMT"
}
]
| 2022-06-10T00:00:00 | [
[
"Gupta",
"Prakash",
""
],
[
"Pathak",
"Anirban",
""
]
]
|
quant-ph/0701184 | Stephen Walborn | M. P. Almeida, F. de Melo, M. Hor-Meyll, A. Salles, S. P. Walborn, P.
H. Souto Ribeiro and L. Davidovich | Experimental Observation of Environment-induced Sudden Death of
Entanglement | 4 pages, 4 figures | null | 10.1117/12.724472 | null | quant-ph | null | We demonstrate the difference between local, single-particle dynamics and
global dynamics of entangled quantum systems coupled to independent
environments. Using an all-optical experimental setup, we show that, while the
environment-induced decay of each system is asymptotic, quantum entanglement
may suddenly disappear. This "sudden death" constitutes yet another distinct
and counter-intuitive trait of entanglement.
| [
{
"version": "v1",
"created": "Thu, 25 Jan 2007 20:57:24 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Almeida",
"M. P.",
""
],
[
"de Melo",
"F.",
""
],
[
"Hor-Meyll",
"M.",
""
],
[
"Salles",
"A.",
""
],
[
"Walborn",
"S. P.",
""
],
[
"Ribeiro",
"P. H. Souto",
""
],
[
"Davidovich",
"L.",
""
]
]
|
quant-ph/0701185 | Matthias Schork | Toufik Mansour, Matthias Schork | On the normal ordering of multi-mode boson operators | 16 pages; typos corrected | null | 10.1007/s11503-008-1009-6 | null | quant-ph | null | In this article combinatorial aspects of normal ordering annihilation and
creation operators of a multi-mode boson system are discussed. The modes are
assumed to be coupled since otherwise the problem of normal ordering is reduced
to the corresponding problem of the single-mode case. To describe the normal
ordering in the multi-mode case for each mode a colour is introduced and
coloured contractions are considered. A depiction for coloured contractions via
coloured linear representations is given. In analogy to the single-mode case
associated coloured Stirling numbers are defined as coefficients appearing in
the process of normal ordering powers of the number operators. Several
properties of these coloured Stirling numbers are discussed.
| [
{
"version": "v1",
"created": "Thu, 25 Jan 2007 21:34:14 GMT"
},
{
"version": "v2",
"created": "Mon, 19 Mar 2007 21:50:18 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Mansour",
"Toufik",
""
],
[
"Schork",
"Matthias",
""
]
]
|
quant-ph/0701186 | Aidan Burch | Aidan Burch | Phase Space Representations and Perturbation Theory for Continuous-time
Histories | 22 pages; slightly shortened, more concise argumentation; ref. added | J.Math.Phys.48:072106,2007 | 10.1063/1.2752009 | null | quant-ph gr-qc | null | We consider two technical developments of the formalism of continuous-time
histories. First, we provide an explicit description of histories of the simple
harmonic oscillator on the classical histories phase space, comparing and
contrasting the Q, P and Wigner representations; we conclude that a
representation based on coherent states is the most appropriate. Second, we
demonstrate a generic method for implementing a perturbative approach for
interacting theories in the histories formalism, using the quartic anharmonic
oscillator. We make use of the identification of the closed-time path (CTP)
generating functional with the decoherence functional to develop a perturbative
expansion for the latter up to second order in the coupling constant. We
consider both configuration space and phase space histories.
| [
{
"version": "v1",
"created": "Thu, 25 Jan 2007 22:19:18 GMT"
},
{
"version": "v2",
"created": "Mon, 23 Jul 2007 23:01:09 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Burch",
"Aidan",
""
]
]
|
quant-ph/0701187 | Daowen Qiu | Daowen Qiu | Some observations on two-way finite automata with quantum and classical
states | Comments and suggestions are welcome | Lecture Notes in Computer Science, vol. 5226, pp.1-8, 2008. | null | null | quant-ph | null | {\it Two-way finite automata with quantum and classical states} (2qcfa's)
were introduced by Ambainis and Watrous. Though this computing model is more
restricted than the usual {\it two-way quantum finite automata} (2qfa's) first
proposed by Kondacs and Watrous, it is still more powerful than the classical
counterpart. In this note, we focus on dealing with the operation properties of
2qcfa's. We prove that the Boolean operations (intersection, union, and
complement) and the reversal operation of the class of languages recognized by
2qcfa's with error probabilities are closed; as well, we verify that the
catenation operation of such class of languages is closed under certain
restricted condition. The numbers of states of these 2qcfa's for the above
operations are presented. Some examples are included, and $\{xx^{R}|x\in
\{a,b\}^{*},#_{x}(a)=#_{x}(b)\}$ is shown to be recognized by 2qcfa with
one-sided error probability, where $x^{R}$ is the reversal of $x$, and
$#_{x}(a)$ denotes the $a$'s number in string $x$.
| [
{
"version": "v1",
"created": "Fri, 26 Jan 2007 05:48:37 GMT"
}
]
| 2010-03-10T00:00:00 | [
[
"Qiu",
"Daowen",
""
]
]
|
quant-ph/0701188 | Yang Xiang | Yang Xiang, Shi-Jie Xiong, Fang-Yu Hong | The Bound of Entanglement of Superpositions with More Than Two
Components | 5 pages;v2: version to be pulished in The European Physical Journal D | null | 10.1140/epjd/e2008-00022-6 | null | quant-ph | null | A bipartite quantum state (for two systems in any dimensions) can be
decomposed as a superposition of many components. For a superposition of more
than two components we prove that there is a bound of the entanglement of the
superposition state which can be expressed according to entanglements of its
component states. Especially, if the component states are mutually
bi-orthogonal, the entanglement of the superposition state can be exactly given
in terms of the entanglements of the states being superposed.
| [
{
"version": "v1",
"created": "Fri, 26 Jan 2007 06:03:26 GMT"
},
{
"version": "v2",
"created": "Sun, 10 Feb 2008 03:38:17 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Xiang",
"Yang",
""
],
[
"Xiong",
"Shi-Jie",
""
],
[
"Hong",
"Fang-Yu",
""
]
]
|
quant-ph/0701189 | Aalok Pandya | Aalok | Background Independent Quantum Mechanics, Metric of Quantum States, and
Gravity: A Comprehensive Perspective | 25 Pages;journal reference added:Published in- Int. J. Theor. Phys.
46 (2007) 3216-3229. References revised | Int. J. Theor. Phys. 46 (2007) 3216-3229 | 10.1007/s10773-007-9438-7 | UOR/THEP/2007/0126/Revised | quant-ph gr-qc hep-th | null | This paper presents a comprehensive perspective of the metric of quantum
states with a focus on the background independent metric structures. We also
explore the possibilities of geometrical formulations of quantum mechanics
beyond the quantum state space and Kahler manifold. The metric of quantum
states in the classical configuration space with the pseudo-Riemannian
signature and its possible applications are explored. On contrary to the common
perception that a metric for quantum state can yield a natural metric in the
configuration space with the limit when Planck constant vanishes, we obtain the
metric of quantum states in the configuration space without imposing this
limiting condition. Here, Planck constant is absorbed in the quantity like Bohr
radii. While exploring the metric structure associated with Hydrogen like atom,
we witness another interesting finding that the invariant lengths appear in the
multiple of Bohr radii.
| [
{
"version": "v1",
"created": "Fri, 26 Jan 2007 11:41:53 GMT"
},
{
"version": "v2",
"created": "Sun, 30 Mar 2008 11:09:30 GMT"
}
]
| 2008-03-30T00:00:00 | [
[
"Aalok",
"",
""
]
]
|
quant-ph/0701190 | D.-A. Deckert | D.-A. Deckert, D. Duerr, P. Pickl | Quantum Dynamics with Bohmian Trajectories | 17 pages, 18 figures; some typos corrected, 4 figures added, some
paragraphs extended, source code extended | J. Phys. Chem. A, 111, 41, 10325 - 10330, 2007 | 10.1021/jp0711996 | null | quant-ph | null | We describe the advantages and disadvantages of numerical methods when
Bohmian trajectory-grids are used for numerical simulations of quantum
dynamics. We focus on the crucial non crossing property of Bohmian
trajectories, which numerically must be paid careful attention to. Failure to
do so causes instabilities or leads to false simulations.
| [
{
"version": "v1",
"created": "Fri, 26 Jan 2007 16:47:02 GMT"
},
{
"version": "v2",
"created": "Sun, 13 May 2007 11:53:46 GMT"
}
]
| 2011-11-09T00:00:00 | [
[
"Deckert",
"D. -A.",
""
],
[
"Duerr",
"D.",
""
],
[
"Pickl",
"P.",
""
]
]
|
quant-ph/0701191 | Adan Cabello | Adan Cabello, Jan-{\AA}ke Larsson | Minimum detection efficiency for a loophole-free atom-photon Bell
experiment | REVTeX4, 4 pages, 1 figure | Phys. Rev. Lett. 98 (2007) 220402 | 10.1103/PhysRevLett.98.220402 | null | quant-ph | null | In Bell experiments, one problem is to achieve high enough photodetection to
ensure that there is no possibility of describing the results via a local
hidden-variable model. Using the Clauser-Horne inequality and a two-photon
non-maximally entangled state, a photodetection efficiency higher than 0.67 is
necessary. Here we discuss atom-photon Bell experiments. We show that, assuming
perfect detection efficiency of the atom, it is possible to perform a
loophole-free atom-photon Bell experiment whenever the photodetection
efficiency exceeds 0.50.
| [
{
"version": "v1",
"created": "Fri, 26 Jan 2007 16:56:54 GMT"
},
{
"version": "v2",
"created": "Thu, 31 May 2007 17:25:08 GMT"
}
]
| 2022-03-16T00:00:00 | [
[
"Cabello",
"Adan",
""
],
[
"Larsson",
"Jan-Åke",
""
]
]
|
quant-ph/0701192 | Pascal Buenzli | Pascal R. Buenzli, Philippe A. Martin, Marc D. Ryser | Thermal quantum electrodynamics of nonrelativistic charged fluids | 32 pages, 0 figures. 2nd version | Phys. Rev. E 75, 041125, pp. 1--14 (2007) | 10.1103/PhysRevE.75.041125 | null | quant-ph | null | The theory relevant to the study of matter in equilibrium with the radiation
field is thermal quantum electrodynamics (TQED). We present a formulation of
the theory, suitable for non relativistic fluids, based on a joint functional
integral representation of matter and field variables. In this formalism
cluster expansion techniques of classical statistical mechanics become
operative. They provide an alternative to the usual Feynman diagrammatics in
many-body problems which is not perturbative with respect to the coupling
constant. As an application we show that the effective Coulomb interaction
between quantum charges is partially screened by thermalized photons at large
distances. More precisely one observes an exact cancellation of the dipolar
electric part of the interaction, so that the asymptotic particle density
correlation is now determined by relativistic effects. It has still the
$r^{-6}$ decay typical for quantum charges, but with an amplitude strongly
reduced by a relativistic factor.
| [
{
"version": "v1",
"created": "Fri, 26 Jan 2007 18:15:44 GMT"
},
{
"version": "v2",
"created": "Fri, 23 Feb 2007 19:01:55 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Buenzli",
"Pascal R.",
""
],
[
"Martin",
"Philippe A.",
""
],
[
"Ryser",
"Marc D.",
""
]
]
|
quant-ph/0701193 | Mehmet Dagli | Mehmet Dagli, Domenico D'Alessandro, Jonathan D.H. Smith | A General Framework for Recursive Decompositions of Unitary Quantum
Evolutions | 17 pages. To appear in J. Phys. A: Math. Theor. This article replaces
our earlier preprint "A Recursive Decomposition of Unitary Operators on N
Qubits." The current version provides a general method to generate recursive
decompositions of unitary evolutions. Several decompositions obtained before
are shown to be as a special case of this general procedure | null | 10.1088/1751-8113/41/15/155302 | null | quant-ph | null | Decompositions of the unitary group U(n) are useful tools in quantum
information theory as they allow one to decompose unitary evolutions into local
evolutions and evolutions causing entanglement. Several recursive
decompositions have been proposed in the literature to express unitary
operators as products of simple operators with properties relevant in
entanglement dynamics. In this paper, using the concept of grading of a Lie
algebra, we cast these decompositions in a unifying scheme and show how new
recursive decompositions can be obtained. In particular, we propose a new
recursive decomposition of the unitary operator on $N$ qubits, and we give a
numerical example.
| [
{
"version": "v1",
"created": "Fri, 26 Jan 2007 18:43:53 GMT"
},
{
"version": "v2",
"created": "Tue, 5 Feb 2008 05:24:30 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Dagli",
"Mehmet",
""
],
[
"D'Alessandro",
"Domenico",
""
],
[
"Smith",
"Jonathan D. H.",
""
]
]
|
quant-ph/0701194 | Samuel Kutin | Samuel A. Kutin, David Petrie Moulton, Lawren M. Smithline | Computation at a distance | 19 pages | null | null | null | quant-ph | null | We consider a model of computation motivated by possible limitations on
quantum computers. We have a linear array of n wires, and we may perform
operations only on pairs of adjacent wires. Our goal is to build a circuits
that perform specified operations spanning all n wires. We show that the
natural lower bound of n-1 on circuit depth is nearly tight for a variety of
problems, and we prove linear upper bounds for additional problems. In
particular, using only gates adding a wire (mod 2) into an adjacent wire, we
can realize any linear operation in GL_n(2) as a circuit of depth 5n. We show
that some linear operations require depth at least 2n+1.
| [
{
"version": "v1",
"created": "Fri, 26 Jan 2007 19:48:41 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Kutin",
"Samuel A.",
""
],
[
"Moulton",
"David Petrie",
""
],
[
"Smithline",
"Lawren M.",
""
]
]
|
quant-ph/0701195 | Todd Pittman | T.B. Pittman, B.C. Jacobs, and J.D. Franson | Investigation of a single-photon source based on quantum interference | Submitted to the New J. Phys. Focus Issue on "Measurement-based
quantum information processing" | New J. Phys. 9, 195 (2007) | 10.1088/1367-2630/9/6/195 | null | quant-ph | null | We report on an experimental investigation of a single-photon source based on
a quantum interference effect first demonstrated by Koashi, Matsuoka, and
Hirano [Phys. Rev. A 53, 3621 (1996)]. For certain types of measurement-based
quantum information processing applications this technique may be useful as a
high rate, but random, source of single photons.
| [
{
"version": "v1",
"created": "Fri, 26 Jan 2007 19:51:55 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Pittman",
"T. B.",
""
],
[
"Jacobs",
"B. C.",
""
],
[
"Franson",
"J. D.",
""
]
]
|
quant-ph/0701196 | Marcos C. de Oliveira | Luis F. Haruna, Marcos C. de Oliveira | Physical properties of the Schur complement of local covariance matrices | 10 pages. Replaced with final published version | J. Phys. A: Math. Theor. 40, 14205 (2007) | 10.1088/1751-8113/40/47/011 | null | quant-ph math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | General properties of global covariance matrices representing bipartite
Gaussian states can be decomposed into properties of local covariance matrices
and their Schur complements. We demonstrate that given a bipartite Gaussian
state $\rho_{12}$ described by a $4\times 4$ covariance matrix \textbf{V}, the
Schur complement of a local covariance submatrix $\textbf{V}_1$ of it can be
interpreted as a new covariance matrix representing a Gaussian operator of
party 1 conditioned to local parity measurements on party 2. The connection
with a partial parity measurement over a bipartite quantum state and the
determination of the reduced Wigner function is given and an operational
process of parity measurement is developed. Generalization of this procedure to
a $n$-partite Gaussian state is given and it is demonstrated that the $n-1$
system state conditioned to a partial parity projection is given by a
covariance matrix such as its $2 \times 2$ block elements are Schur complements
of special local matrices.
| [
{
"version": "v1",
"created": "Fri, 26 Jan 2007 22:44:51 GMT"
},
{
"version": "v2",
"created": "Wed, 9 Jul 2008 12:23:38 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Haruna",
"Luis F.",
""
],
[
"de Oliveira",
"Marcos C.",
""
]
]
|
quant-ph/0701197 | Liang Qiu | Liang Qiu, An Min Wang | Scheme for remote implementation of partially unknown quantum operation
of two qubits in cavity QED | 7 pages, 2 figures | null | 10.1088/0253-6102/50/5/44 | null | quant-ph | null | By constructing the recovery operations of the protocol of remote
implementation of partially unknown quantum operation of two qubits [An Min
Wang: PRA, \textbf{74}, 032317(2006)], we present a scheme to implement it in
cavity QED. Long-lived Rydberg atoms are used as qubits, and the interaction
between the atoms and the field of cavity is a nonresonant one. Finally, we
analyze the experimental feasibility of this scheme.
| [
{
"version": "v1",
"created": "Sat, 27 Jan 2007 02:18:39 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Qiu",
"Liang",
""
],
[
"Wang",
"An Min",
""
]
]
|
quant-ph/0701198 | Vladimir Mashkevich | Vladimir S. Mashkevich (Queens College) | On Nondemolition Measurements of Photon Number: A Comment on
quant-ph/0612031 | 5 pages, LaTex 2e | null | null | null | quant-ph | null | Experimental results stated in quant-ph/0612031 are seminal: The authors have
realized nondemolition measurements of the photon number. As to the
interpretation of the results, it seems to be less than convincing: The
treatment of the system state and of the role of measurement is not compatible
with the conventional point of view. We propose an adequate treatment, in which
the experimental results are a manifestation of a partial Zeno effect (a
slowdown of relaxation).
| [
{
"version": "v1",
"created": "Sat, 27 Jan 2007 04:15:59 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Mashkevich",
"Vladimir S.",
"",
"Queens College"
]
]
|
quant-ph/0701199 | Carlo Di Franco | C. Di Franco, M. Paternostro, M. S. Kim | Noise resilience and entanglement evolution in two non-equivalent
classes of quantum algorithms | 10 pages, 9 figures, RevTeX4 | Phys. Rev. A 75, 052316 (2007) | 10.1103/PhysRevA.75.052316 | null | quant-ph | null | The speed-up provided by quantum algorithms with respect to their classical
counterparts is at the origin of scientific interest in quantum computation.
However, the fundamental reasons for such a speed-up are not yet completely
understood and deserve further attention. In this context, the classical
simulation of quantum algorithms is a useful tool that can help us in gaining
insight. Starting from the study of general conditions for classical
simulation, we highlight several important differences between two
non-equivalent classes of quantum algorithms. We investigate their performance
under realistic conditions by quantitatively studying their resilience with
respect to static noise. This latter refers to errors affecting the inital
preparation of the register used to run an algorithm. We also compare the
evolution of the entanglement involved in the different computational
processes.
| [
{
"version": "v1",
"created": "Sat, 27 Jan 2007 15:12:24 GMT"
},
{
"version": "v2",
"created": "Tue, 15 May 2007 16:53:04 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Di Franco",
"C.",
""
],
[
"Paternostro",
"M.",
""
],
[
"Kim",
"M. S.",
""
]
]
|
quant-ph/0701200 | Stephan Olson | S. Jay Olson, Jonathan P. Dowling | Information and measurement in generally covariant quantum theory | 4 pages, 2 figures, reference added, typos corrected, discussion
added, PACS numbers added | null | null | null | quant-ph gr-qc | null | Due to the absence of an external, classical time variable, the probabilistic
predictions of covariant quantum theory are ambiguous when multiple
measurements are considered. Here, we introduce an information theoretic
framework to the covariant formalism, and use it to interpret the measurement
process. We find that the time ordering of measurements emerges as an entropy
relationship in the state of the observers, giving unique probabilities for
multiple measurements. This approach suggests a new, fully self-contained
probability interpretation for generally covariant quantum physics, which makes
use of a quantum mechanical description of the observer, in contrast to
standard quantum mechanics which assumes an external, classical observer.
| [
{
"version": "v1",
"created": "Sun, 28 Jan 2007 04:26:52 GMT"
},
{
"version": "v2",
"created": "Mon, 14 May 2007 18:50:34 GMT"
},
{
"version": "v3",
"created": "Fri, 18 Jan 2008 12:19:24 GMT"
}
]
| 2011-11-09T00:00:00 | [
[
"Olson",
"S. Jay",
""
],
[
"Dowling",
"Jonathan P.",
""
]
]
|
quant-ph/0701201 | Robert R. Tucci | Robert R. Tucci | Factorization of Quantum Density Matrices According to Bayesian and
Markov Networks | 48 pages (files: 1 .tex, 1 .sty, 7 .eps) | null | null | null | quant-ph | null | We show that any quantum density matrix can be represented by a Bayesian
network (a directed acyclic graph), and also by a Markov network (an undirected
graph). We show that any Bayesian or Markov net that represents a density
matrix, is logically equivalent to a set of conditional independencies
(symmetries) satisfied by the density matrix. We show that the d-separation
theorems of classical Bayesian and Markov networks generalize in a simple and
natural way to quantum physics. The quantum d-separation theorems are shown to
be closely connected to quantum entanglement. We show that the graphical rules
for d-separation can be used to detect pairs of nodes (or of node sets) in a
graph that are unentangled. CMI entanglement (a.k.a. squashed entanglement), a
measure of entanglement originally discovered by analyzing Bayesian networks,
is an important part of the theory of this paper.
| [
{
"version": "v1",
"created": "Sun, 28 Jan 2007 19:48:34 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Tucci",
"Robert R.",
""
]
]
|
quant-ph/0701202 | Wei Huang | Wei Huang | An explicit family of unitaries with exponentially minimal length Pauli
geodesics | 4 pages, accepted as poster presentation in QIP07 | null | null | null | quant-ph | null | Recently, Nielsen et al have proposed a geometric approach to quantum
computation. They've shown that the size of the minimum quantum circuits
implementing a unitary U, up to polynomial factors, equals to the length of
minimal geodesic from identity I through U. They've investigated a large class
of solutions to the geodesic equation, called Pauli geodesics. They've raised a
natural question whether we can explicitly construct a family of unitaries U
that have exponentially long minimal length Pauli geodesics? We give a positive
answer to this question.
| [
{
"version": "v1",
"created": "Sun, 28 Jan 2007 22:54:39 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Huang",
"Wei",
""
]
]
|
quant-ph/0701203 | Jiannis Pachos | Jiannis K. Pachos, Agapitos Hatzinikitas, Michael Stone | Zero modes of various graphene configurations from the index theorem | 7 pages, 1 figure. Proceedings of the Graphene Conference, MPI PKS
Dresden, September 2006 | Eur. Phys. J., Special Topics, 148, 127 (2007) | 10.1140/epjst/e2007-00232-6 | null | quant-ph | null | In this article we consider a graphene sheet that is folded in various
compact geometries with arbitrary topology described by a certain genus, $g$.
While the Hamiltonian of these systems is defined on a lattice one can take the
continuous limit. The obtained Dirac-like Hamiltonian describes well the low
energy modes of the initial system. Starting from first principles we derive an
index theorem that corresponds to this Hamiltonian. This theorem relates the
zero energy modes of the graphene sheet with the topology of the compact
lattice. For $g=0$ and $g=1$ these results coincide with the analytical and
numerical studies performed for fullerene molecules and carbon nanotubes while
for higher values of $g$ they give predictions for more complicated molecules.
| [
{
"version": "v1",
"created": "Sun, 28 Jan 2007 23:37:54 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Pachos",
"Jiannis K.",
""
],
[
"Hatzinikitas",
"Agapitos",
""
],
[
"Stone",
"Michael",
""
]
]
|
quant-ph/0701204 | Eric Cavalcanti | E. G. Cavalcanti and M. D. Reid | Signatures for generalized macroscopic superpositions | 4 pages, 2 figures, some changes made | Phys. Rev. Lett. 97, 170405 (2006) | 10.1103/PhysRevLett.97.170405 | null | quant-ph | null | We develop criteria sufficient to enable detection of macroscopic coherence
where there are not just two macroscopically distinct outcomes for a pointer
measurement, but rather a spread of outcomes over a macroscopic range. The
criteria provide a means to distinguish a macroscopic quantum description from
a microscopic one based on mixtures of microscopic superpositions of
pointer-measurement eigenstates. The criteria are applied to Gaussian-squeezed
and spin-entangled states.
| [
{
"version": "v1",
"created": "Mon, 29 Jan 2007 01:36:30 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Cavalcanti",
"E. G.",
""
],
[
"Reid",
"M. D.",
""
]
]
|
quant-ph/0701205 | Nageswaran Rajendran | T. S. Mahesh, Nageswaran Rajendran, Xinhua Peng and Dieter Suter | Factorizing Numbers with the Gauss Sum Technique: NMR Implementations | 4 pages, 4 figures; Abstract and Conclusion are slightly modified.
References added and formatted with Bibtex | null | 10.1103/PhysRevA.75.062303 | null | quant-ph | null | Several physics-based algorithms for factorizing large number were recently
published. A notable recent one by Schleich et al. uses Gauss sums for
distinguishing between factors and non-factors. We demonstrate two NMR
techniques that evaluate Gauss sums and thus implement their algorithm. The
first one is based on differential excitation of a single spin magnetization by
a cascade of RF pulses. The second method is based on spatial averaging and
selective refocusing of magnetization for Gauss sums corresponding to factors.
All factors of 16637 and 52882363 are successfully obtained.
| [
{
"version": "v1",
"created": "Mon, 29 Jan 2007 09:14:39 GMT"
},
{
"version": "v2",
"created": "Fri, 16 Mar 2007 18:07:31 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Mahesh",
"T. S.",
""
],
[
"Rajendran",
"Nageswaran",
""
],
[
"Peng",
"Xinhua",
""
],
[
"Suter",
"Dieter",
""
]
]
|
quant-ph/0701206 | Ramazan Sever | Cevdet Tezcan, Metin Aktas, Ozlem Yesiltas Ramazan Sever | Exact solution of Schrodinger equation for Pseudoharmonic potential | 10 pages | J.Math.Chem.43:845,2007 | 10.1007/s10910-007-9233-y | null | quant-ph | null | Exact solution of Schrodinger equation for the pseudoharmonic potential is
obtained for an arbitrary angular momentum. The energy eigenvalues and
corresponding eigenfunctions are calculated by Nikiforov-Uvarov method.
Wavefunctions are expressed in terms of Jacobi polynomials. The energy
eigenvalues are calculated numerically for some values of l and n with n<5 for
some diatomic molecules.
| [
{
"version": "v1",
"created": "Mon, 29 Jan 2007 09:29:47 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Tezcan",
"Cevdet",
""
],
[
"Aktas",
"Metin",
""
],
[
"Sever",
"Ozlem Yesiltas Ramazan",
""
]
]
|
quant-ph/0701207 | Jean-Baptiste Trebbia | Jean-Baptiste Trebbia (LCFIO), Carlos Leonardo Garrido Alzar (LCFIO),
Ronald Cornelussen (LCFIO), Christoph I. Westbrook (LCFIO), Isabelle
Bouchoule (LCFIO) | Roughness suppression via rapid current modulation on an atom chip | null | Physical Review Letters (29/01/2007) 4 | null | null | quant-ph cond-mat.other | null | We present a method to suppress the potential roughness of a wire-based,
magnetic atom guide: modulating the wire current at a few tens of kHz, the
potential roughness, which is proportional to the wire current, averages to
zero. Using ultra-cold $^{87}{\rm Rb}$ clouds, we show experimentally that
modulation reduces the roughness by at least of a factor five without
measurable heating or atom loss. This roughness suppression results in a
dramatic reduction of the damping of center of mass oscillations.
| [
{
"version": "v1",
"created": "Mon, 29 Jan 2007 10:47:59 GMT"
},
{
"version": "v2",
"created": "Wed, 20 Jun 2007 12:13:34 GMT"
}
]
| 2007-06-20T00:00:00 | [
[
"Trebbia",
"Jean-Baptiste",
"",
"LCFIO"
],
[
"Alzar",
"Carlos Leonardo Garrido",
"",
"LCFIO"
],
[
"Cornelussen",
"Ronald",
"",
"LCFIO"
],
[
"Westbrook",
"Christoph I.",
"",
"LCFIO"
],
[
"Bouchoule",
"Isabelle",
"",
"LCFIO"
]
]
|
quant-ph/0701208 | Enrique Solano | L. Lamata, J. Leon, T. Schaetz, and E. Solano | Dirac Equation and Quantum Relativistic Effects in a Single Trapped Ion | 4 pages and 1 figure, minor corrections, accepted for publication in
Physical Review Letters | Phys.Rev.Lett.98:253005,2007 | 10.1103/PhysRevLett.98.253005 | null | quant-ph cond-mat.mes-hall hep-ph | null | We present a method of simulating the Dirac equation in 3+1 dimensions for a
free spin-1/2 particle in a single trapped ion. The Dirac bispinor is
represented by four ionic internal states, and position and momentum of the
Dirac particle are associated with the respective ionic variables. We show also
how to simulate the simplified 1+1 case, requiring the manipulation of only two
internal levels and one motional degree of freedom. Moreover, we study relevant
quantum-relativistic effects, like the Zitterbewegung and Klein's paradox, the
transition from massless to massive fermions, with the relativistic and
nonrelativistic limits, via the tuning of controllable experimental parameters.
| [
{
"version": "v1",
"created": "Mon, 29 Jan 2007 18:39:11 GMT"
},
{
"version": "v2",
"created": "Sun, 20 May 2007 19:01:50 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Lamata",
"L.",
""
],
[
"Leon",
"J.",
""
],
[
"Schaetz",
"T.",
""
],
[
"Solano",
"E.",
""
]
]
|
quant-ph/0701209 | Xue Fei | Fei Xue, Yu-xi Liu, C. P. Sun, Franco Nori | Two-Mode Squeezed States and Entangled States of Two Mechanical
Resonators | 9 pages, 3 figures | Phys. Rev. B 76, 064305 (2007) | 10.1103/PhysRevB.76.064305 | null | quant-ph cond-mat.mes-hall | null | We study a device consisting of a dc-SQUID with two sections of its loop
acting as two mechanical resonators. An analog of the parametric
down-conversion process in quantum optics can be realized with this device. We
show that a two-mode squeezed state can be generated for two overdamped
mechanical resonators, where the damping constants of the two mechanical
resonators are larger than the coupling strengths between the dc-SQUID and the
two mechanical resonators. Thus we show that entangled states of these two
mechanical resonators can be generated.
| [
{
"version": "v1",
"created": "Mon, 29 Jan 2007 11:51:05 GMT"
},
{
"version": "v2",
"created": "Thu, 14 Jun 2007 12:38:08 GMT"
},
{
"version": "v3",
"created": "Fri, 15 Jun 2007 04:43:40 GMT"
}
]
| 2007-10-23T00:00:00 | [
[
"Xue",
"Fei",
""
],
[
"Liu",
"Yu-xi",
""
],
[
"Sun",
"C. P.",
""
],
[
"Nori",
"Franco",
""
]
]
|
quant-ph/0701210 | Andr\'as Vukics | A. Vukics and H. Ritsch | C++QED: An object-oriented framework for wave-function simulations of
cavity QED systems | 31 pages, 8 figures, 3 tables | European Physical Journal D, Volume 44, number 3, 2007 | 10.1140/epjd/e2007-00210-x | null | quant-ph | null | We present a framework for efficiently performing Monte Carlo wave-function
simulations in cavity QED with moving particles. It relies heavily on the
object-oriented programming paradigm as realised in C++, and is extensible and
applicable for simulating open interacting quantum dynamics in general. The
user is provided with a number of ``elements'', eg pumped moving particles,
pumped lossy cavity modes, and various interactions to compose complex
interacting systems, which contain several particles moving in electromagnetic
fields of various configurations, and perform wave-function simulations on such
systems. A number of tools are provided to facilitate the implementation of new
elements.
| [
{
"version": "v1",
"created": "Mon, 29 Jan 2007 14:44:51 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Vukics",
"A.",
""
],
[
"Ritsch",
"H.",
""
]
]
|
quant-ph/0701211 | Michel R. P. Planat | Michel Planat (FEMTO-ST), Metod Saniga (AISAVSLOVAK Academy of
Sciences) | On the Pauli graphs of N-qudits | 17 pages. Expanded section on two-qutrits, Quantum Information and
Computation (2007) accept\'e | Quantum Information and Computation 8, 1-2 (2008) 127-146 | null | null | quant-ph math-ph math.MP | null | A comprehensive graph theoretical and finite geometrical study of the
commutation relations between the generalized Pauli operators of N-qudits is
performed in which vertices/points correspond to the operators and edges/lines
join commuting pairs of them. As per two-qubits, all basic properties and
partitionings of the corresponding Pauli graph are embodied in the geometry of
the generalized quadrangle of order two. Here, one identifies the operators
with the points of the quadrangle and groups of maximally commuting subsets of
the operators with the lines of the quadrangle. The three basic partitionings
are (a) a pencil of lines and a cube, (b) a Mermin's array and a bipartite-part
and (c) a maximum independent set and the Petersen graph. These factorizations
stem naturally from the existence of three distinct geometric hyperplanes of
the quadrangle, namely a set of points collinear with a given point, a grid and
an ovoid, which answer to three distinguished subsets of the Pauli graph,
namely a set of six operators commuting with a given one, a Mermin's square,
and set of five mutually non-commuting operators, respectively. The generalized
Pauli graph for multiple qubits is found to follow from symplectic polar spaces
of order two, where maximal totally isotropic subspaces stand for maximal
subsets of mutually commuting operators. The substructure of the (strongly
regular) N-qubit Pauli graph is shown to be pseudo-geometric, i. e., isomorphic
to a graph of a partial geometry. Finally, the (not strongly regular) Pauli
graph of a two-qutrit system is introduced; here it turns out more convenient
to deal with its dual in order to see all the parallels with the two-qubit case
and its surmised relation with the generalized quadrangle Q(4, 3), the dual
ofW(3).
| [
{
"version": "v1",
"created": "Mon, 29 Jan 2007 15:00:03 GMT"
},
{
"version": "v2",
"created": "Wed, 21 Feb 2007 10:39:47 GMT"
},
{
"version": "v3",
"created": "Mon, 11 Jun 2007 14:52:38 GMT"
}
]
| 2007-08-29T00:00:00 | [
[
"Planat",
"Michel",
"",
"FEMTO-ST"
],
[
"Saniga",
"Metod",
"",
"AISAVSLOVAK Academy of\n Sciences"
]
]
|
quant-ph/0701212 | Ramin Golestanian | Arash Ashourvan, MirFaez Miri, and Ramin Golestanian | Non-contact rack and pinion powered by the lateral Casimir force | 4 pages, submitted for publication on 17 Jan 07 | Phys. Rev. Lett. 98, 140801 (2007) | 10.1103/PhysRevLett.98.140801 | null | quant-ph cond-mat.stat-mech physics.atom-ph | null | The lateral Casimir force is employed to propose a design for a potentially
wear-proof rack and pinion with no contact, which can be miniaturized to
nano-scale. The robustness of the design is studied by exploring the relation
between the pinion velocity and the rack velocity in the different domains of
the parameter space. The effects of friction and added external load are also
examined. It is shown that the device can hold up extremely high velocities,
unlike what the general perception of the Casimir force as a weak interaction
might suggest.
| [
{
"version": "v1",
"created": "Mon, 29 Jan 2007 15:47:20 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Ashourvan",
"Arash",
""
],
[
"Miri",
"MirFaez",
""
],
[
"Golestanian",
"Ramin",
""
]
]
|
quant-ph/0701213 | Jaime Julve | J. Julve and F. J. de Urries | Infinite plane wave evolution in a 1-D square quantum barrier | 17 pages | null | null | null | quant-ph | null | We analytically compute the time evolution of an initial infinite plane wave
in the presence of a 1-dimensional square quantum barrier. This calculation
generalizes the analysis of the shutter problem and sets the basis for the
calculation of the transmission of general wave packets, aiming to work out the
explicit contribution of the resonant (Gamow) states. The method relies mainly
on the analytical properties of the Green function. The role of separate
boundary conditions on the Green function and on the evolution equation is
highlighted. As in previous works on related problems, only the determination
of the resonant momenta requires numerical methods.
| [
{
"version": "v1",
"created": "Mon, 29 Jan 2007 17:08:44 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Julve",
"J.",
""
],
[
"de Urries",
"F. J.",
""
]
]
|
quant-ph/0701214 | Werner Vogel | Th. Richter, W. Vogel | Nonclassical characteristic functions for highly sensitive measurements | 4 pages, 3 figures | null | 10.1103/PhysRevA.76.053835 | null | quant-ph | null | Characteristic functions are shown to be useful for highly sensitive
measurements. Redistributions of motional Fock states of a trapped atom can be
directly monitored via the most fragile nonclassical part of the characteristic
function. The method can also be used for decoherence measurements in optical
quantum-information systems.
| [
{
"version": "v1",
"created": "Mon, 29 Jan 2007 17:17:33 GMT"
},
{
"version": "v2",
"created": "Fri, 26 Oct 2007 09:36:22 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Richter",
"Th.",
""
],
[
"Vogel",
"W.",
""
]
]
|
quant-ph/0701215 | Christian Roos | C. F. Roos, M. Chwalla, K. Kim, M. Riebe, and R. Blatt | 'Designer atoms' for quantum metrology | null | Nature 443, 316 (2006) | 10.1038/nature05101 | null | quant-ph physics.atom-ph | null | Entanglement is recognized as a key resource for quantum computation and
quantum cryptography. For quantum metrology, the use of entangled states has
been discussed and demonstrated as a means of improving the signal-to-noise
ratio. In addition, entangled states have been used in experiments for
efficient quantum state detection and for the measurement of scattering
lengths. In quantum information processing, manipulation of individual quantum
bits allows for the tailored design of specific states that are insensitive to
the detrimental influences of an environment. Such 'decoherence-free subspaces'
protect quantum information and yield significantly enhanced coherence times.
Here we use a decoherence-free subspace with specifically designed entangled
states to demonstrate precision spectroscopy of a pair of trapped Ca+ ions; we
obtain the electric quadrupole moment, which is of use for frequency standard
applications. We find that entangled states are not only useful for enhancing
the signal-to-noise ratio in frequency measurements - a suitably designed pair
of atoms also allows clock measurements in the presence of strong technical
noise. Our technique makes explicit use of non-locality as an entanglement
property and provides an approach for 'designed' quantum metrology.
| [
{
"version": "v1",
"created": "Mon, 29 Jan 2007 18:12:52 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Roos",
"C. F.",
""
],
[
"Chwalla",
"M.",
""
],
[
"Kim",
"K.",
""
],
[
"Riebe",
"M.",
""
],
[
"Blatt",
"R.",
""
]
]
|
quant-ph/0701216 | Alex Monras | Alex Monras and Matteo G. A. Paris | Optimal quantum estimation of loss in bosonic channels | 4 pages, 2 figures, replaced with published version | Phys. Rev. Lett. 98, 160401 (2007) | 10.1103/PhysRevLett.98.160401 | null | quant-ph | null | We address the estimation of the loss parameter of a bosonic channel probed
by Gaussian signals. We derive the ultimate quantum bound on precision and show
that no improvement may be obtained by having access to the environment degrees
of freedom. We found that, for small losses, the variance of the optimal
estimator is proportional to the loss parameter itself, a result that
represents a qualitative improvement over the shot noise limit. An observable
based on the symmetric logarithmic derivative is derived, which attains the
ultimate bound and may be implemented using Gaussian operations and photon
counting.
| [
{
"version": "v1",
"created": "Mon, 29 Jan 2007 18:30:05 GMT"
},
{
"version": "v2",
"created": "Wed, 7 Feb 2007 11:48:00 GMT"
},
{
"version": "v3",
"created": "Sat, 10 Mar 2007 07:20:27 GMT"
},
{
"version": "v4",
"created": "Wed, 6 Jun 2007 15:30:43 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Monras",
"Alex",
""
],
[
"Paris",
"Matteo G. A.",
""
]
]
|
quant-ph/0701217 | Giacomo Mauro D'Ariano | Giacomo Mauro D'Ariano | No-signaling, dynamical independence, and the local observability
principle | Presented at the conference "Theory and Technology in Quantum
Information, Communication, Computation and Cryptography", Trieste SISSA,
June 2006. Submitted to J. Phys. A. Math. Gen | null | 10.1088/1751-8113/40/28/S19 | null | quant-ph | null | Within a general operational framework I show that a-causality at a distance
of "local actions" (the so-called "no-signaling") is a direct consequence of
commutativity of local transformations, i.e. of dynamical independence. On the
other hand, the tensor product of Quantum Mechanics is not just a consequence
of such dynamical independence, but needs in addition the Local Observability
Principle.
| [
{
"version": "v1",
"created": "Mon, 29 Jan 2007 18:37:39 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"D'Ariano",
"Giacomo Mauro",
""
]
]
|
quant-ph/0701218 | Bassano Vacchini | B.Vacchini | On the precise connection between the GRW master-equation and
master-equations for the description of decoherence | 9 pages, latex, no figures, to appear on J. Phys. A | J. Phys. A: Math. Theor. 40 (2007) 2463-2473 | 10.1088/1751-8113/40/10/015 | null | quant-ph | null | We point out that the celebrated GRW master-equation is invariant under
translations, reflecting the homogeneity of space, thus providing a particular
realization of a general class of translation-covariant Markovian
master-equations. Such master-equations are typically used for the description
of decoherence due to momentum transfers between system and environment.
Building on this analogy we show the exact relationship between the GRW
master-equation and decoherence master-equations, further providing a
collisional decoherence model formally equivalent to the GRW master-equation.
This allows for a direct comparison of order of magnitudes of relevant
parameters. This formal analogy should not lead to confusion on the utterly
different spirit of the two research fields, in particular it has to be
stressed that the decoherence approach does not lead to a solution of the
measurement problem. Building on this analogy however the feasibility of the
extension of spontaneous localization models in order to avoid the infinite
energy growth is discussed. Apart from a particular case considered in the
paper, it appears that the amplification mechanism is generally spoiled by such
modifications.
| [
{
"version": "v1",
"created": "Mon, 29 Jan 2007 18:43:50 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Vacchini",
"B.",
""
]
]
|
quant-ph/0701219 | Giacomo Mauro D'Ariano | Giacomo Mauro D'Ariano | Operational axioms for a C*-algebraic formulation of Quantum Mechanics | Presented at the International Conference QCM&C (Quantum
Communications, Measurements and Computing), 28 November-3 December 2006,
Tsukuba, Japan | null | null | null | quant-ph | null | A C*-algebra formulation of Quantum Mechanics is derived from purely
operational axioms in which the primary role is played by the "transformations"
that the system undergoes in the course of an "experiment". The notion of the
{\em adjoint} of a transformation is based on the postulated existence of
"faithful states" that allows one to calibrate the experimental apparatus.
| [
{
"version": "v1",
"created": "Mon, 29 Jan 2007 18:48:08 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"D'Ariano",
"Giacomo Mauro",
""
]
]
|
quant-ph/0701220 | Christopher Ogden | C. D. Ogden, M. Paternostro, M. S. Kim | Concentration and purification of entanglement for qubit systems with
ancillary cavity fields | 10 pages, 6 figures | Phys. Rev. A 75, 042325 (2007) | 10.1103/PhysRevA.75.042325 | null | quant-ph | null | We propose schemes for entanglement concentration and purification for qubit
systems encoded in flying atomic pairs. We use a cavity-quantum electrodynamics
setting as the paradigmatic scenario within which our proposals can be
implemented. Maximally entangled pure states of qubits can be produced as a
result of our protocols. In particular, the concentration protocol yields Bell
states with the largest achievable theoretical probability while the
purification scheme produces arbitrarily pure Bell states. The requirements for
the implementation of these protocols are modest, within the state of the art,
and we address all necessary steps in two specific set-ups based on
experimentally mature microwave technology.
| [
{
"version": "v1",
"created": "Mon, 29 Jan 2007 20:58:46 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Ogden",
"C. D.",
""
],
[
"Paternostro",
"M.",
""
],
[
"Kim",
"M. S.",
""
]
]
|
quant-ph/0701221 | Fabrizio Illuminati | Gerardo Adesso (University of Salerno), Fabrizio Illuminati
(University of Salerno) | Entanglement in continuous variable systems: Recent advances and current
perspectives | 61 pages, 7 figures, 3 tables; Published as Topical Review in J.
Phys. A, Special Issue on Quantum Information, Communication, Computation and
Cryptography (v3: few typos corrected) | J. Phys. A 40, 7821 (2007) | 10.1088/1751-8113/40/28/S01 | null | quant-ph cond-mat.stat-mech hep-th math-ph math.MP physics.optics | null | We review the theory of continuous-variable entanglement with special
emphasis on foundational aspects, conceptual structures, and mathematical
methods. Much attention is devoted to the discussion of separability criteria
and entanglement properties of Gaussian states, for their great practical
relevance in applications to quantum optics and quantum information, as well as
for the very clean framework that they allow for the study of the structure of
nonlocal correlations. We give a self-contained introduction to phase-space and
symplectic methods in the study of Gaussian states of infinite-dimensional
bosonic systems. We review the most important results on the separability and
distillability of Gaussian states and discuss the main properties of bipartite
entanglement. These include the extremal entanglement, minimal and maximal, of
two-mode mixed Gaussian states, the ordering of two-mode Gaussian states
according to different measures of entanglement, the unitary (reversible)
localization, and the scaling of bipartite entanglement in multimode Gaussian
states. We then discuss recent advances in the understanding of entanglement
sharing in multimode Gaussian states, including the proof of the monogamy
inequality of distributed entanglement for all Gaussian states, and its
consequences for the characterization of multipartite entanglement. We finally
review recent advances and discuss possible perspectives on the qualification
and quantification of entanglement in non Gaussian states, a field of research
that is to a large extent yet to be explored.
| [
{
"version": "v1",
"created": "Mon, 29 Jan 2007 21:08:12 GMT"
},
{
"version": "v2",
"created": "Fri, 2 Mar 2007 13:48:25 GMT"
},
{
"version": "v3",
"created": "Wed, 27 Jun 2007 14:36:50 GMT"
}
]
| 2009-07-02T00:00:00 | [
[
"Adesso",
"Gerardo",
"",
"University of Salerno"
],
[
"Illuminati",
"Fabrizio",
"",
"University of Salerno"
]
]
|
quant-ph/0701222 | Julia Stasi\'nska | Remigiusz Augusiak, Julia Stasi\'nska | Rotationally invariant bipartite states and bound entanglement | 11 pages, 4 figures, accepted for publication in Physics Letters A | Phys. Lett. A 363, pp. 182-191 (2007) | 10.1016/j.physleta.2006.11.036 | null | quant-ph | null | We consider rotationally invariant states in $\mathbb{C}^{N_{1}}\ot
\mathbb{C}^{N_{2}}$ Hilbert space with even $N_{1}\geq 4$ and arbitrary
$N_{2}\geq N_{1}$, and show that in such case there always exist states which
are inseparable and remain positive after partial transposition, and thus the
PPT criterion does not suffice to prove separability of such systems. We
demonstrate it applying a map developed recently by Breuer [H.-P. Breuer, Phys.
Rev. Lett {\bf 97}, 080501 (2006)] to states that remain invariant after
partial time reversal.
| [
{
"version": "v1",
"created": "Mon, 29 Jan 2007 22:32:41 GMT"
}
]
| 2016-08-14T00:00:00 | [
[
"Augusiak",
"Remigiusz",
""
],
[
"Stasińska",
"Julia",
""
]
]
|
quant-ph/0701223 | Damien James Martin | Damien Martin | Is PT-symmetric quantum mechanics just quantum mechanics in a
non-orthogonal basis? | 16 pages; references added, sign error fixed | null | null | null | quant-ph hep-th | null | One of the postulates of quantum mechanics is that the Hamiltonian is
Hermitian, as this guarantees that the eigenvalues are real. Recently there has
been an interest in asking if $H^\dagger = H$ is a necessary condition, and has
lead to the development of PT-symmetric quantum mechanics. This note shows that
any finite physically acceptable non-Hermitian Hamiltonian is equivalent to
doing ordinary quantum mechanics in a non-orthogonal basis. In particular, this
means that there is no experimental distinction between PT-symmetric quantum
mechanics and ordinary quantum mechanics for finite systems. In particular, the
claim that PT-symmetric quantum mechanics allows for faster evolution than
Hermitian quantum mechanics is shown to be a problem of physical
interpretation.
| [
{
"version": "v1",
"created": "Mon, 29 Jan 2007 22:46:27 GMT"
},
{
"version": "v2",
"created": "Sat, 17 Feb 2007 23:40:53 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Martin",
"Damien",
""
]
]
|
quant-ph/0701224 | Luc Bouten | Luc Bouten, John K. Stockton, Gopal Sarma and Hideo Mabuchi | Scattering of polarized laser light by an atomic gas in free space: a
QSDE approach | 9 pages, 2 figures | Phys. Rev. A 75, 052111 (2007) | 10.1103/PhysRevA.75.052111 | null | quant-ph | null | We propose a model, based on a quantum stochastic differential equation
(QSDE), to describe the scattering of polarized laser light by an atomic gas.
The gauge terms in the QSDE account for the direct scattering of the laser
light into different field channels. Once the model has been set, we can
rigorously derive quantum filtering equations for balanced polarimetry and
homodyne detection experiments, study the statistics of output processes and
investigate a strong driving, weak coupling limit.
| [
{
"version": "v1",
"created": "Tue, 30 Jan 2007 19:24:06 GMT"
}
]
| 2013-05-29T00:00:00 | [
[
"Bouten",
"Luc",
""
],
[
"Stockton",
"John K.",
""
],
[
"Sarma",
"Gopal",
""
],
[
"Mabuchi",
"Hideo",
""
]
]
|
quant-ph/0701225 | Guido Bacciagaluppi | Guido Bacciagaluppi | Probability, Arrow of Time and Decoherence | 26 pages | null | null | null | quant-ph | null | This paper relates both to the metaphysics of probability and to the physics
of time asymmetry. Using the formalism of decoherent histories, it investigates
whether intuitions about intrinsic time directedness that are often associated
with probability can be justified in the context of no-collapse approaches to
quantum mechanics. The standard (two-vector) approach to time symmetry in the
decoherent histories literature is criticised, and an alternative approach is
proposed, based on two decoherence conditions ('forwards' and 'backwards')
within the one-vector formalism. In turn, considerations of forwards and
backwards decoherence and of decoherence and recoherence suggest that a
time-directed interpretation of probabilities, if adopted, should be both
contingent and perspectival.
| [
{
"version": "v1",
"created": "Tue, 30 Jan 2007 03:37:11 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Bacciagaluppi",
"Guido",
""
]
]
|
quant-ph/0701226 | Kaige Wang | De-Zhong Cao, Jun Xiong, Hua Tang, Lu-Fang Lin, Su-Heng Zhang, and
Kaige Wang | Complementarity in a macroscopic observation | 6 pages, 4 figures | null | null | null | quant-ph | null | Complementarity is usually considered as a phenomenon of microscopic systems.
In this paper we report an experimental observation of complementarity in the
correlated double-slit interference with a pseudothermal light source. The
thermal light beam is divided into test and reference beams which are
correlated with each other. The double-slit is set in the test arm, and the
interference pattern can be observed in the intensity correlation between the
two arms. The experimental results show that the disappearance of interference
fringe depends on whether which-path information is gained through the
reference arm. The experiment therefore witnesses the complementarity occurring
in a macroscopic system.
| [
{
"version": "v1",
"created": "Tue, 30 Jan 2007 11:14:58 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Cao",
"De-Zhong",
""
],
[
"Xiong",
"Jun",
""
],
[
"Tang",
"Hua",
""
],
[
"Lin",
"Lu-Fang",
""
],
[
"Zhang",
"Su-Heng",
""
],
[
"Wang",
"Kaige",
""
]
]
|
quant-ph/0701227 | Ramazan Sever | Ramazan Sever, Mahmut Bucurgat, Cevdet Tezcan, Ozlem Yesiltas | Bound state solution of the Schrodinger equation for Mie potential | 10 pages | J. Math, Chem. 43, 749(2007) | null | null | quant-ph | null | Exact solution of Schrodinger equation for the Mie potential is obtained for
an arbitrary angular momentum. The energy eigenvalues and the corresponding
wavefunctions are calculated by the use of the Nikiforov-Uvarov method.
Wavefunctions are expressed in terms of Jacobi polynomials. The bound states
are calculated numerically for some values of l and $n$ with n<5. They are
applied to several diatomic molecules.
| [
{
"version": "v1",
"created": "Tue, 30 Jan 2007 12:05:52 GMT"
},
{
"version": "v2",
"created": "Mon, 28 Jan 2008 08:31:10 GMT"
}
]
| 2008-01-28T00:00:00 | [
[
"Sever",
"Ramazan",
""
],
[
"Bucurgat",
"Mahmut",
""
],
[
"Tezcan",
"Cevdet",
""
],
[
"Yesiltas",
"Ozlem",
""
]
]
|
quant-ph/0701228 | Pawel Maslanka | K.Andrzejewski, K.Bolonek, J.Gonera, P.Maslanka | Canonical formalism and quantization of perturbative sector of
higher-derivative theories | 16 pages, no figures | null | 10.1103/PhysRevA.76.032110 | null | quant-ph | null | The theories defined by Lagrangians containing second time derivative are
considered. It is shown that if the second derivatives enter only the terms
multiplied by coupling constant one can consistently define the perturbative
sector via Dirac procedure. The possibility of introducing standard canonical
variables is analysed in detail. The ambiguities in quantization procedure are
pointed out.
| [
{
"version": "v1",
"created": "Tue, 30 Jan 2007 12:19:59 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Andrzejewski",
"K.",
""
],
[
"Bolonek",
"K.",
""
],
[
"Gonera",
"J.",
""
],
[
"Maslanka",
"P.",
""
]
]
|
quant-ph/0701229 | Yuri Rostovtsev | Vladimir A. Sautenkov, Hebin Li, Yuri V. Rostovtsev, Marlan O. Scully | Ultra-dispersive adaptive prism | null | Phys. Rev. A 81, 063824 (2010) | 10.1103/PhysRevA.81.063824 | null | quant-ph | null | We have experimentally demonstrated an ultra-dispersive optical prism made
from coherently driven Rb atomic vapor. The prism possesses spectral angular
dispersion that is six orders of magnitude higher than that of a prism made of
optical glass; it is the highest spectral angular dispersion that has ever been
shown (such angular dispersion allows one to spatially resolve light beams with
different frequencies separated by a few kHz). The prism operates near the
resonant frequency of atomic vapor and its dispersion is optically controlled
by a coherent driving field.
| [
{
"version": "v1",
"created": "Tue, 30 Jan 2007 15:42:18 GMT"
}
]
| 2010-07-05T00:00:00 | [
[
"Sautenkov",
"Vladimir A.",
""
],
[
"Li",
"Hebin",
""
],
[
"Rostovtsev",
"Yuri V.",
""
],
[
"Scully",
"Marlan O.",
""
]
]
|
quant-ph/0701230 | Maurice Kibler | O. Albouy (IPNL), M.R. Kibler (IPNL) | SU(2) nonstandard bases: the case of mutually unbiased bases | 33 pages; version2: rescaling of generalized Hadamard matrices,
acknowledgment and references added, misprints corrected; version 3:
published in SIGMA (Symmetry, Integrability and Geometry: Methods and
Applications) at http://www.emis.de/journals/SIGMA/ (22 pages) | SIGMA (Symmetry, Integrability and Geometry: Methods and
Applications) 3 (2007) 076 | null | null | quant-ph math-ph math.MP | null | This paper deals with bases in a finite-dimensional Hilbert space. Such a
space can be realized as a subspace of the representation space of SU(2)
corresponding to an irreducible representation of SU(2). The representation
theory of SU(2) is reconsidered via the use of two truncated deformed
oscillators. This leads to replace the familiar scheme {j^2, j_z} by a scheme
{j^2, v(ra)}, where the two-parameter operator v(ra) is defined in the
enveloping algebra of the Lie algebra su(2). The eigenvectors of the commuting
set of operators {j^2, v(ra)} are adapted to a tower of chains SO(3) > C(2j+1),
2j integer, where C(2j+1) is the cyclic group of order 2j+1. In the case where
2j+1 is prime, the corresponding eigenvectors generate a complete set of
mutually unbiased bases. Some useful relations on generalized quadratic Gauss
sums are exposed in three appendices.
| [
{
"version": "v1",
"created": "Tue, 30 Jan 2007 14:59:27 GMT"
},
{
"version": "v2",
"created": "Sat, 10 Feb 2007 18:08:33 GMT"
},
{
"version": "v3",
"created": "Mon, 9 Jul 2007 09:15:15 GMT"
}
]
| 2009-09-29T00:00:00 | [
[
"Albouy",
"O.",
"",
"IPNL"
],
[
"Kibler",
"M. R.",
"",
"IPNL"
]
]
|
quant-ph/0701231 | Paolo Perinotti Dr. | Paolo Perinotti and Giacomo M. D'Ariano | Optimal estimation of ensemble averages from a quantum measurement | 4 pages, contribution for the proceedings of the QCMC06 at Tsukuba,
Japan. qcmc06.sty | null | null | null | quant-ph | null | We consider the general measurement scenario in which the ensemble average of
an operator is determined via suitable data-processing of the outcomes of a
quantum measurement described by a POVM. After reviewing the optimization of
data processing that minimizes the statistical error of the estimation, we
provide a compact formula for the evaluation of the estimation error.
| [
{
"version": "v1",
"created": "Tue, 30 Jan 2007 15:01:02 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Perinotti",
"Paolo",
""
],
[
"D'Ariano",
"Giacomo M.",
""
]
]
|
quant-ph/0701232 | Miloslav Znojil | Miloslav Znojil | A return to observability near exceptional points in a schematic
PT-symmetric model | 14 pp., 1 fig | Phys. Lett. B 647 (2007) 225 - 230 | 10.1016/j.physletb.2007.01.046 | null | quant-ph | null | Many indefinite-metric (often called pseudo-Hermitian or PT-symmetric)
quantum models H prove "physical" (i.e., Hermitian with respect to an
innovated, ad hoc scalar product) inside a characteristic domain of parameters
D. This means that the energies get complex (= unobservable) beyond the
boundary (= Kato's "exceptional points", EPs). In a solvable example we detect
an enlargement of D caused by the emergence of a new degree of freedom. We
conjecture that such a beneficial mechanism of a return to the real spectrum
near EPs may be generic and largely model-independent.
| [
{
"version": "v1",
"created": "Tue, 30 Jan 2007 15:12:19 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Znojil",
"Miloslav",
""
]
]
|
quant-ph/0701233 | Hongbao Zhang | Song He, Shuxin Shao, and Hongbao Zhang | Quantum Helicity Entropy of Moving Bodies | version to appear in Journal of Physics A as a Fast Track
Communication | J.Phys.A40:F857-F862,2007 | 10.1088/1751-8113/40/36/F02 | null | quant-ph hep-th | null | Lorentz transformation of the reduced helicity density matrix for a massive
spin 1/2 particle is investigated in the framework of relativistic quantum
information theory for the first time. The corresponding helicity entropy is
calculated, which shows no invariant meaning as that of spin. The variation of
the helicity entropy with the relative speed of motion of inertial observers,
however, differs significantly from that of spin due to their distinct
transformation behaviors under the action of Lorentz group. This novel and odd
behavior unique to the helicity may be readily detected by high energy physics
experiments. The underlying physical explanations are also discussed.
| [
{
"version": "v1",
"created": "Tue, 30 Jan 2007 21:04:28 GMT"
},
{
"version": "v2",
"created": "Fri, 2 Feb 2007 15:56:11 GMT"
},
{
"version": "v3",
"created": "Mon, 30 Jul 2007 11:27:49 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"He",
"Song",
""
],
[
"Shao",
"Shuxin",
""
],
[
"Zhang",
"Hongbao",
""
]
]
|
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