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We present a sample- and time-efficient algorithm to learn any bosonic Fock state acted upon by an arbitrary Gaussian unitary. As a special case, this algorithm efficiently learns states produced in Fock state BosonSampling, thus resolving…

In this work, we prove the generation of genuine tripartite continuous-variable entanglement in the unitary dynamics of the simultaneous measurement process of position and momentum observables raised by Arthurs and Kelly, considering a…

Quantum Physics · Physics 2023-07-25 J. A. Mendoza-Fierro , L. M. Arévalo Aguilar

Positivity of the density operator reflects itself in terms of sequences of inequalities on observable moments. Uncertainty relations for non-commuting observables form a subset of these inequalities. In addition, criterion of positivity…

Quantum Physics · Physics 2008-12-21 A R Usha Devi , A K Rajagopal

Quantum thermodynamics can be naturally phrased as a theory of quantum state transformation and energy exchange for small-scale quantum systems undergoing thermodynamical processes, thereby making the resource theoretical approach very well…

Quantum Physics · Physics 2023-07-19 Uttam Singh , Jarosław K. Korbicz , Nicolas J. Cerf

Continuous-variable Gaussian entanglement is an attractive notion, both as a fundamental concept in quantum information theory, based on the well-established Gaussian formalism for phase-space variables, and as a practical resource in…

Quantum Physics · Physics 2026-05-07 E. Shchukin , P. van Loock

We provide necessary and sufficient conditions for the partial transposition of bipartite harmonic quantum states to be nonnegative. The conditions are formulated as an infinite series of inequalities for the moments of the state under…

Quantum Physics · Physics 2009-11-11 E. Shchukin , W. Vogel

In this work we develop new methods for the characterisation of continuous variable quantum states using heterodyne measurement in both the trusted and untrusted settings. First, building on quantum state tomography with heterodyne…

Quantum Physics · Physics 2020-06-09 Ulysse Chabaud , Tom Douce , Frédéric Grosshans , Elham Kashefi , Damian Markham

We show that partial transposition for pure and mixed two-particle states in a discrete $N$-dimensional Hilbert space is equivalent to a change in sign of a "momentum-like" variable of one of the particles in the Wigner function for the…

Quantum Physics · Physics 2017-05-29 Yehuda B. Band , Pier A. Mello

Gaussian bipartite states are basic tools for the realization of quantum information protocols with continuous variables. Their complete characterization is obtained by the reconstruction of the corresponding covariance matrix. Here we…

Quantum Physics · Physics 2016-04-27 D. Buono , G. Nocerino , V. D'Auria , A. Porzio , S. Olivares , M. G. A. Paris

Gaussian states and measurements collectively are not powerful-enough resources for quantum computing, as any Gaussian dynamics can be simulated efficiently, classically. However, it is known that any one non-Gaussian resource -- either a…

Quantum Physics · Physics 2021-12-17 Christos N. Gagatsos , Saikat Guha

We present a framework for deciding whether a quantum state is separable or entangled using covariance matrices of locally measurable observables. This leads to the covariance matrix criterion as a general separability criterion. We…

Quantum Physics · Physics 2008-12-03 Oleg Gittsovich , Otfried Gühne , Philipp Hyllus , Jens Eisert

Detection and classification of entanglement properties of a multi-qubit system is a topic of great interest. This topic has been studied extensively and thus we found different approaches for the detection and classification of multi-qubit…

Quantum Physics · Physics 2023-05-02 Anu Kumari , Satyabrata Adhikari

The convex set of quantum states of a composite $K \times K$ system with positive partial transpose is analysed. A version of the hit and run algorithm is used to generate a sequence of random points covering this set uniformly and an…

Quantum Physics · Physics 2019-02-27 Konrad Szymański , Benoît Collins , Tomasz Szarek , Karol Życzkowski

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…

Quantum Physics · Physics 2016-08-14 Remigiusz Augusiak , Julia Stasińska

Determining whether a quantum state is separable or entangled is a problem of fundamental importance in quantum information science. This is a brief review in which we consider the problem for states in infinite dimensional Hilbert spaces.…

Computational Complexity · Computer Science 2007-05-23 Stefano Mancini , Simone Severini

We consider entanglement distillation from a single-copy of a multipartite state, and instead of rates we analyze the "quality" of the distilled entanglement. This "quality" is quantified by the fidelity with the GHZ-state. We show that…

Quantum Physics · Physics 2009-11-11 Ll. Masanes

Fluctuation theorems (FTs) quantify the thermodynamic reversibility of a system, and for deterministic systems they are defined in terms of the dissipation function. However, in a nonequilibrium steady state of deterministic dynamics, the…

Statistical Mechanics · Physics 2026-03-24 Stephen Sanderson , Charlotte F. Petersen , Debra J. Searles

We consider the transformation of multi-partite states in the single copy setting under positive-partial-transpose-preserving operations (PPT-operations) and obtain both qualitative and quantitative results. Firstly, for some pure state…

Quantum Physics · Physics 2007-05-23 Satoshi Ishizaka , Martin B. Plenio

We study the structure of stationary non equilibrium states for interacting particle systems from a microscopic viewpoint. In particular we discuss two different discrete geometric constructions. We apply both of them to determine non…

Statistical Mechanics · Physics 2017-09-15 Leonardo De Carlo , Davide Gabrielli

We construct a large class of bipartite M x N quantum states which defines a proper subset of states with positive partial transposes (PPT). Any state from this class is PPT but the positivity of its partial transposition is recognized with…

Quantum Physics · Physics 2009-11-13 Dariusz Chruscinski , Jacek Jurkowski , Andrzej Kossakowski