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Nov 7, 2018
11/18

by
M. Wolf

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This paper is in the public domain in USA. Metadata comes from the CrossRef API, see full record in the source URL below.

Topic: journals

Source: https://api.crossref.org/works/10.1093/mnras/67.1.91

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103

Oct 5, 2008
10/08

by
M. Wolf

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Book digitized by Google from the library of Oxford University and uploaded to the Internet Archive by user tpb.

Source: http://books.google.com/books?id=aqsCAAAAQAAJ&oe=UTF-8

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3.0

Nov 7, 2018
11/18

by
M. Wolf

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This paper is in the public domain in USA. Metadata comes from the CrossRef API, see full record in the source URL below.

Topic: journals

Source: https://api.crossref.org/works/10.1093/mnras/63.6.330

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4.0

Nov 7, 2018
11/18

by
M. Wolf

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This paper is in the public domain in USA. Metadata comes from the CrossRef API, see full record in the source URL below.

Topic: journals

Source: https://api.crossref.org/works/10.1093/mnras/63.8.506

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3.0

Nov 7, 2018
11/18

by
M. Wolf

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This paper is in the public domain in USA. Metadata comes from the CrossRef API, see full record in the source URL below.

Topic: journals

Source: https://api.crossref.org/works/10.1093/mnras/63.5.303

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3.0

Nov 7, 2018
11/18

by
M. Wolf

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This paper is in the public domain in USA. Metadata comes from the CrossRef API, see full record in the source URL below.

Topic: journals

Source: https://api.crossref.org/works/10.1093/mnras/64.2.112

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Nov 7, 2018
11/18

by
M. Wolf

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This paper is in the public domain in USA. Metadata comes from the CrossRef API, see full record in the source URL below.

Topic: journals

Source: https://api.crossref.org/works/10.1093/mnras/68.3.180

0
0.0

Jun 30, 2018
06/18

by
M. Wolf; J. Berezovsky

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We perform photoluminescence excitation measurements on individual CdSe/ZnS nanocrystal quantum dots (NCQDs) at room temperature to study optical transition energies and broadening. The observed features in the spectra are identified and compared to calculated transition energies using an effective mass model. The observed broadening is attributed to phonon broadening, spectral diffusion and size and shape inhomogeneity. The former two contribute the broadening transitions in individual QDs...

Topics: Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1407.5548

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Sep 17, 2013
09/13

by
P. Zasche; M. Wolf

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Three eclipsing binary systems with astrometric orbit have been studied. For a detailed analysis two circular-orbit binaries (VW Cep and HT Vir) and one binary with an eccentric orbit (zeta Phe) have been chosen. Merging together astrometry and the analysis of the times of minima, one is able to describe the orbit of such a system completely. The O-C diagrams and the astrometric orbits of the third bodies were analysed simultaneously for these three systems by the least-squares method. The...

Source: http://arxiv.org/abs/0711.3980v1

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303

Oct 30, 2006
10/06

by
Anna W. M. Wolf

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Sep 22, 2013
09/13

by
P. Zasche; M. Wolf

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Our main aim is the first detailed analysis of the two eclipsing binaries V456 Oph and V490 Cyg. The system V456 Oph has been studied both photometrically via an analysis of its light curve observed by the INTEGRAL/OMC and by the period analysis of all available times of minima. V490 Cyg has been studied by means of a period analysis only. Many new times of minima for both systems have recently been observed and derived. This allows us for the first time to study in detail the processes that...

Source: http://arxiv.org/abs/1101.5269v1

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Sep 20, 2013
09/13

by
J. Cislo; M. Wolf

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We investigate the relation between the Riesz and the Baez-Duarte criterion for the Riemann Hypothesis. In particular we present the relation between the function $R(x)$ appearing in the Riesz criterion and the sequence $c_k$ appearing in the Baez-Duarte formulation. It is shown that $R(x)$ can expressed by $c_k$ and vice versa the sequence $c_k$ can be obtained from the values of $R(x)$ at integer arguments. We give also some relations involving $c_k$ and $R(x)$, in particular value of the...

Source: http://arxiv.org/abs/math/0607782v1

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Sep 18, 2013
09/13

by
K. Malachowski; M. Wolf

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A mathematical model of radiotherapy is proposed. The study used the classical 24 hours way of fractionation with a weekend pause. We introduce the matrices of ``radiotherapy'' and ``growth''. We developed an equation of the fraction cell evolution, which we solved numerically. The results indicate that the accelerated growth of cells occurs due to the decrease of the fraction of slowly growing cells and increase of the cells that are fast growing.

Source: http://arxiv.org/abs/math/0605132v1

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Sep 21, 2013
09/13

by
J. Cislo; M. Wolf

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We give a brief overview of a few criteria equivalent to the Riemann Hypothesis. Next we concentrate on the Riesz and B{\'a}ez-Duarte criteria. We proof that they are equivalent and we provide some computer data to support them. It is not compressed to six pages version of the talk delivered by M.W. during the XXVII Workshop on Geometrical Methods in Physics, 28 June -- 6 July, 2008, Bia{\l}owie{\.z}a, Poland.

Source: http://arxiv.org/abs/0808.0640v2

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Jan 18, 2017
01/17

by
Anna W. M. Wolf

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Book Source: Digital Library of India Item 2015.58500 dc.contributor.author: Anna W. M. Wolf dc.date.accessioned: 2015-06-29T19:32:57Z dc.date.available: 2015-06-29T19:32:57Z dc.date.copyrightexpirydate: 0000-00-00 dc.date.digitalpublicationdate: 2004-05-13 dc.date.citation: 1942 dc.identifier: RMSC, IIIT-H dc.identifier.barcode: 128979 dc.identifier.origpath: /data6/upload/0149/486 dc.identifier.copyno: 1 dc.identifier.uri: http://www.new.dli.ernet.in/handle/2015/58500...

Topic: RMSC

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Sep 18, 2013
09/13

by
Michael M. Wolf

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We provide a generalization of the normal mode decomposition for non-symmetric or locality constrained situations. This allows for instance to locally decouple a bipartitioned collection of arbitrarily correlated oscillators up to elementary pairs into which all correlations are condensed. Similarly, it enables us to decouple the interaction parts of multi-mode channels into single-mode and pair-interactions where the latter are shown to be a clear signature of squeezing between system and...

Source: http://arxiv.org/abs/0707.0604v2

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Sep 22, 2013
09/13

by
Oleg Szehr; Michael M. Wolf

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We investigate the stability of quantum Markov processes with respect to perturbations of their transition maps. In the first part, we introduce a condition number that measures the sensitivity of fixed points of a quantum channel to perturbations. We establish upper and lower bounds on this condition number in terms of subdominant eigenvalues of the transition map. In the second part, we consider quantum Markov processes that converge to a unique stationary state and we analyze the stability...

Source: http://arxiv.org/abs/1210.1171v2

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Sep 18, 2013
09/13

by
J. Eisert; M. M. Wolf

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This article gives an elementary introduction to quantum computing. It is a draft for a book chapter of the "Handbook of Nature-Inspired and Innovative Computing", Eds. A. Zomaya, G.J. Milburn, J. Dongarra, D. Bader, R. Brent, M. Eshaghian-Wilner, F. Seredynski (Springer, Berlin Heidelberg New York, 2006).

Source: http://arxiv.org/abs/quant-ph/0401019v3

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Sep 24, 2013
09/13

by
M. M. Wolf; J. Eisert

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We consider the additivity of the minimal output entropy and the classical information capacity of a class of quantum channels. For this class of channels the norm of the output is maximized for the output being a normalized projection. We prove the additivity of the minimal output Renyi entropies with entropic parameters contained in [0, 2], generalizing an argument by Alicki and Fannes, and present a number of examples in detail. In order to relate these results to the classical information...

Source: http://arxiv.org/abs/quant-ph/0412133v3

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Jul 19, 2013
07/13

by
Teiko Heinosaari; Michael M. Wolf

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We consider pairs of quantum observables (POVMs) and analyze the relation between the notions of non-disturbance, joint measurability and commutativity. We specify conditions under which these properties coincide or differ---depending for instance on the interplay between the number of outcomes and the Hilbert space dimension or on algebraic properties of the effect operators. We also show that (non-)disturbance is in general not a symmetric relation and that it can be decided and quantified by...

Source: http://arxiv.org/abs/1005.5659v2

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69

Jul 20, 2013
07/13

by
David Reeb; Michael M. Wolf

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We prove a lower bound on the relative entropy between two finite-dimensional states in terms of their entropy difference and the dimension of the underlying space. The inequality is tight in the sense that equality can be attained for any prescribed value of the entropy difference, both for quantum and classical systems. We outline implications for thermodynamics and information theory, such as a necessary condition for a process to be close to thermodynamic reversibility, or an easily...

Source: http://arxiv.org/abs/1304.0036v1

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47

Sep 18, 2013
09/13

by
Motohisa Fukuda; Michael M. Wolf

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We study the additivity problems for the classical capacity of quantum channels, the minimal output entropy and its convex closure. We show for each of them that additivity for arbitrary pairs of channels holds iff it holds for arbitrary equal pairs, which in turn can be taken to be unital. In a similar sense, weak additivity is shown to imply strong additivity for any convex entanglement monotone. The implications are obtained by considering direct sums of channels (or states) for which we...

Source: http://arxiv.org/abs/0704.1092v2

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1.0

Jun 30, 2018
06/18

by
Oleg Szehr; Michael M. Wolf

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This article investigates the stability of the ground state subspace of a canonical parent Hamiltonian of a Matrix product state against local perturbations. We prove that the spectral gap of such a Hamiltonian remains stable under weak local perturbations even in the thermodynamic limit, where the entire perturbation might not be bounded. Our discussion is based on preceding work by D.A. Yarotsky that develops a perturbation theory for relatively bounded quantum perturbation of classical...

Topics: Quantum Physics, Mathematics, Mathematical Physics, Statistical Mechanics, Condensed Matter

Source: http://arxiv.org/abs/1402.4175

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Jun 28, 2018
06/18

by
Oleg Szehr; Michael M. Wolf

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We investigate elementary topological properties of sets of completely positive (CP) maps that arise in quantum Perron-Frobenius theory. We prove that the set of primitive CP maps of fixed Kraus rank is path-connected and we provide a complete classification of the connected components of irreducible CP maps at given Kraus rank and fixed peripheral spectrum in terms of a multiplicity index. These findings are then applied to analyse 1D quantum phases by studying equivalence classes of...

Topics: Quantum Physics, Mathematical Physics, Mathematics, General Topology

Source: http://arxiv.org/abs/1506.07550

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47

Sep 18, 2013
09/13

by
J. Eisert; M. M. Wolf

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This article provides an elementary introduction to Gaussian channels and their capacities. We review results on the classical, quantum, and entanglement assisted capacities and discuss related entropic quantities as well as additivity issues. Some of the known results are extended. In particular, it is shown that the quantum conditional entropy is maximized by Gaussian states and that some implications for additivity problems can be extended to the Gaussian setting.

Source: http://arxiv.org/abs/quant-ph/0505151v1

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0.0

Jun 30, 2018
06/18

by
Martin Idel; Michael M. Wolf

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Sinkhorn proved that every entry-wise positive matrix can be made doubly stochastic by multiplying with two diagonal matrices. In this note we prove a recently conjectured analogue for unitary matrices: every unitary can be decomposed into two diagonal unitaries and one whose row- and column sums are equal to one. The proof is non-constructive and based on a reformulation in terms of symplectic topology. As a corollary, we obtain a decomposition of unitary matrices into an interlaced product of...

Topics: Quantum Physics, Mathematics, Mathematical Physics

Source: http://arxiv.org/abs/1408.5728

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Jun 28, 2018
06/18

by
Michael Kech; Michael M. Wolf

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We analyze quantum state tomography in scenarios where measurements and states are both constrained. States are assumed to live in a semi-algebraic subset of state space and measurements are supposed to be rank-one POVMs, possibly with additional constraints. Specifically, we consider sets of von Neumann measurements and sets of local observables. We provide upper bounds on the minimal number of measurement settings or outcomes that are required for discriminating all states within the given...

Topics: Quantum Physics, Information Theory, Computing Research Repository, Mathematical Physics,...

Source: http://arxiv.org/abs/1507.00903

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29

Jul 20, 2013
07/13

by
Robert Koenig; Michael M. Wolf

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We investigate permutation-invariant continuous variable quantum states and their covariance matrices. We provide a complete characterization of the latter with respect to permutation-invariance, exchangeability and representing convex combinations of tensor power states. On the level of the respective density operators this leads to necessary criteria for all these properties which become necessary and sufficient for Gaussian states. For these we use the derived results to provide de...

Source: http://arxiv.org/abs/0804.3070v1

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Sep 18, 2013
09/13

by
Karl Gerd H. Vollbrecht; Michael M. Wolf

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We discuss conditional Renyi and Tsallis entropies for bipartite quantum systems of finite dimension. We investigate the relation between the positivity of conditional entropies and entanglement properties. It is in particular shown that any state having a negative conditional entropy with respect to any value of the entropic parameter is distillable since it violates the reduction criterion. Moreover we show that the entanglement of Werner states in odd dimensions can neither be detected by...

Source: http://arxiv.org/abs/quant-ph/0202058v1

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Jun 30, 2018
06/18

by
Motohisa Fukuda; Ion Nechita; Michael M. Wolf

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We study quantum channels with respect to their image, i.e., the image of the set of density operators under the action of the channel. We first characterize the set of quantum channels having polytopic images and show that additivity of the minimal output entropy can be violated in this class. We then provide a complete characterization of quantum channels $T$ that are universally image additive in the sense that for any quantum channel $S$, the image of $T \otimes S$ is the convex hull of the...

Topics: Quantum Physics, Mathematics, Mathematical Physics

Source: http://arxiv.org/abs/1408.2340

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56

Sep 19, 2013
09/13

by
K. G. H. Vollbrecht; M. M. Wolf

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We provide generalizations of known two-qubit entanglement distillation protocols for arbitrary Hilbert space dimensions. The protocols, which are analogues of the hashing and breeding procedures, are adapted to bipartite quantum states which are diagonal in a basis of maximally entangled states. We show that the obtained rates are optimal, and thus equal to the distillable entanglement, for a (d-1) parameter family of rank deficient states. Methods to improve the rates for other states are...

Source: http://arxiv.org/abs/quant-ph/0208152v1

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Sep 19, 2013
09/13

by
Antonio Acin; Valerio Scarani; Michael M. Wolf

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The relation between Bell inequalities with two two-outcome measurements per site and distillability is analyzed in systems of an arbitrary number of quantum bits. We observe that the violation of any of these inequalities by a quantum state implies that pure-state entanglement can be distilled from it. The corresponding distillation protocol may require that some of the parties join into several groups. We show that there exists a link between the amount of the Bell inequality violation and...

Source: http://arxiv.org/abs/quant-ph/0206084v1

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Sep 19, 2013
09/13

by
R. F. Werner; M. M. Wolf

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We construct a set of 2^(2^n) independent Bell correlation inequalities for n-partite systems with two dichotomic observables each, which is complete in the sense that the inequalities are satisfied if and only if the correlations considered allow a local classical model. All these inequalities can be summarized in a single, albeit non-linear inequality. We show that quantum correlations satisfy this condition provided the state has positive partial transpose with respect to any grouping of the...

Source: http://arxiv.org/abs/quant-ph/0102024v1

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Sep 22, 2013
09/13

by
Karl Gerd H. Vollbrecht; Michael M. Wolf

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We show that bipartite quantum states of any dimension, which do not have a positive partial transpose, become 1-distillable when one adds an infinitesimal amount of bound entanglement. To this end we investigate the activation properties of a new class of symmetric bound entangled states of full rank. It is shown that in this set there exist universal activator states capable of activating the distillation of any NPPT state.

Source: http://arxiv.org/abs/quant-ph/0201103v2

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Sep 20, 2013
09/13

by
Michael M. Wolf; David Perez-Garcia

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We investigate the quantum capacity of noisy quantum channels which can be represented by coupling a system to an effectively small environment. A capacity formula is derived for all cases where both system and environment are two-dimensional--including all extremal qubit channels. Similarly, for channels acting on higher dimensional systems we show that the capacity can be determined if the channel arises from a sufficiently small coupling to a qubit environment. Extensions to instances of...

Source: http://arxiv.org/abs/quant-ph/0607070v1

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29

Sep 21, 2013
09/13

by
Oleg Szehr; David Reeb; Michael M. Wolf

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We introduce a new framework that yields spectral bounds on norms of functions of transition maps for finite, homogeneous Markov chains. The techniques employed work for bounded semigroups, in particular for classical as well as for quantum Markov chains and they do not require additional assumptions like detailed balance, irreducibility or aperiodicity. We use the method in order to derive convergence bounds that improve significantly upon known spectral bounds. The core technical observation...

Source: http://arxiv.org/abs/1301.4827v1

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Sep 23, 2013
09/13

by
Teiko Heinosaari; Luca Mazzarella; Michael M. Wolf

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We provide a detailed analysis of the question: how many measurement settings or outcomes are needed in order to identify a quantum system which is constrained by prior information? We show that if the prior information restricts the system to a set of lower dimensionality, then topological obstructions can increase the required number of outcomes by a factor of two over the number of real parameters needed to characterize the system. Conversely, we show that almost every measurement becomes...

Source: http://arxiv.org/abs/1109.5478v2

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Sep 17, 2013
09/13

by
P. Zasche; M. Wolf; P. Svoboda

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The contact eclipsing binary system XX Leonis (P = 0.97 days, sp A8) has been analysed using the PHOEBE programme, based on the Wilson Devinney code. The BVRI light curves were obtained during spring 2006 using the 20-cm telescope and ST-7 CCD detector. The effective temperature of the primary component determined from the photometric analysis is T=(7889+/-61)K, the inclination of the orbit is i=(89.98+/-2.45)deg and the photometric mass ratio q=(0.41+/-0.01). Also the third body hypothesis was...

Source: http://arxiv.org/abs/0711.2955v1

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Jul 20, 2013
07/13

by
A. Serafini; J. Eisert; M. M. Wolf

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We address the question of the multiplicativity of the maximal p-norm output purities of bosonic Gaussian channels under Gaussian inputs. We focus on general Gaussian channels resulting from the reduction of unitary dynamics in larger Hilbert spaces. It is shown that the maximal output purity of tensor products of single-mode channels under Gaussian inputs is multiplicative for any p>1 for products of arbitrary identical channels as well as for a large class of products of different...

Source: http://arxiv.org/abs/quant-ph/0406065v1

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Jul 19, 2013
07/13

by
Michael M. Wolf; David Perez-Garcia

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Given a list of n complex numbers, when can it be the spectrum of a quantum channel, i.e., a completely positive trace preserving map? We provide an explicit solution for the n=4 case and show that in general the characterization of the non-zero part of the spectrum can essentially be given in terms of its classical counterpart - the non-zero spectrum of a stochastic matrix. A detailed comparison between the classical and quantum case is given. We discuss applications of our findings in the...

Source: http://arxiv.org/abs/1005.4545v1

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Sep 17, 2013
09/13

by
Kristan Temme; Michael M. Wolf; Frank Verstraete

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Stochastic exclusion processes play an integral role in the physics of non-equilibrium statistical mechanics. These models are Markovian processes, described by a classical master equation. In this paper a quantum mechanical version of a stochastic hopping process in one dimension is formulated in terms of a quantum master equation. This allows the investigation of coherent and stochastic evolution in the same formal framework. The focus lies on the non-equilibrium steady state. Two stochastic...

Source: http://arxiv.org/abs/0912.0858v2

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Jul 20, 2013
07/13

by
Reinhard F. Werner; Michael M. Wolf

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We study violations of n particle Bell inequalities (as developed by Mermin and Klyshko) under the assumption that suitable partial transposes of the density operator are positive. If all transposes with respect to a partition of the system into p subsystems are positive, the best upper bound on the violation is 2^((n-p)/2). In particular, if the partial transposes with respect to all subsystems are positive, the inequalities are satisfied. This is supporting evidence for a recent conjecture by...

Source: http://arxiv.org/abs/quant-ph/9910063v1

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Jun 29, 2018
06/18

by
Martin Idel; Daniel Lercher; Michael M. Wolf

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We propose and analyse a mathematical measure for the amount of squeezing contained in a continuous variable quantum state. We show that the proposed measure operationally quantifies the minimal amount of squeezing needed to prepare a given quantum state and that it can be regarded as a squeezing analogue of the "entanglement of formation". We prove that the measure is convex and superadditive and we provide analytic bounds as well as a numerical convex optimisation algorithm for its...

Topics: Mathematical Physics, Quantum Physics, Mathematics

Source: http://arxiv.org/abs/1607.00873

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Sep 20, 2013
09/13

by
A. Claret; G. Torres; M. Wolf

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For the past three decades, and until recently, there has been a serious discrepancy between the observed and theoretical values of the apsidal motion rate dw/dt of the eccentric eclipsing binary DI Her, which has even been interpreted occasionally as a possible failure of General Relativity (GR). Recent observations of the Rossiter-McLaughlin effect have shown convincingly that the reason for the anomaly is that the rotational axes of the stars and the orbital axis are misaligned, which...

Source: http://arxiv.org/abs/1002.2949v1

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Sep 18, 2013
09/13

by
Michael M. Wolf; J. Ignacio Cirac

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We investigate the possibility of dividing quantum channels into concatenations of other channels, thereby studying the semigroup structure of the set of completely-positive trace-preserving maps. We show the existence of 'indivisible' channels which can not be written as non-trivial products of other channels and study the set of 'infinitesimal divisible' channels which are elements of continuous completely positive evolutions. For qubit channels we obtain a complete characterization of the...

Source: http://arxiv.org/abs/math-ph/0611057v3

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Jul 20, 2013
07/13

by
Karl G. H. Vollbrecht; Michael M. Wolf

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We discuss the discriminating power of separability criteria, which are based on the spectrum of a quantum state and its reductions. Common examples are entropic inequalities utilizing conditional Tsallis or Renyi entropies. We prove that these inequalities are implied by the reduction criterion for any positive value of the entropic parameters. We show however, that arbitrary sets of criteria based on spectral and local information can never be sufficient by establishing a separable,...

Source: http://arxiv.org/abs/quant-ph/0107014v1

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Jul 20, 2013
07/13

by
R. F. Werner; M. M. Wolf

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We discuss the entanglement properties of bipartite states with Gaussian Wigner functions. Separability and the positivity of the partial transpose are characterized in terms of the covariance matrix of the state, and it is shown that for systems composed of a single oscillator for Alice and an arbitrary number for Bob, positivity of the partial transpose implies separability. However, this implications fails with two oscillators on each side, as we show by a five parameter family of explicit...

Source: http://arxiv.org/abs/quant-ph/0009118v1

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Sep 18, 2013
09/13

by
Daniel Lercher; Géza Giedke; Michael M. Wolf

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The quantum capacity of bosonic Gaussian quantum channels can be non-additive in a particularly striking way: a pair of such optical-fiber type channels can individually have zero quantum capacity but super-activate each other such that the combined channel has strictly positive capacity. This has been shown in [Nature Photonics 5, 624 (2011)] where it was conjectured that squeezing is a necessary resource for this phenomenon. We provide a proof of this conjecture by showing that for gauge...

Source: http://arxiv.org/abs/1209.5574v2

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Sep 18, 2013
09/13

by
Christian B. Mendl; Michael M. Wolf

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The set of doubly-stochastic quantum channels and its subset of mixtures of unitaries are investigated. We provide a detailed analysis of their structure together with computable criteria for the separation of the two sets. When applied to O(d)-covariant channels this leads to a complete characterization and reveals a remarkable feature: instances of channels which are not in the convex hull of unitaries can return to it when either taking finitely many copies of them or supplementing with a...

Source: http://arxiv.org/abs/0806.2820v1

49
49

Sep 21, 2013
09/13

by
Michael M. Wolf; David Perez-Garcia

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Using tools from classical signal processing, we show how to determine the dimensionality of a quantum system as well as the effective size of the environment's memory from observable dynamics in a model-independent way. We discuss the dependence on the number of conserved quantities, the relation to ergodicity and prove a converse showing that a Hilbert space of dimension D+2 is sufficient to describe every bounded sequence of measurements originating from any D-dimensional linear equations of...

Source: http://arxiv.org/abs/0901.2542v2