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Gaussian states are widely regarded as one of the most relevant classes of continuous-variable (CV) quantum states, as they naturally arise in physical systems and play a key role in quantum technologies. This motivates a fundamental…

Measures of entanglement, fidelity and purity are basic yardsticks in quantum information processing. We propose how to implement these measures using linear devices and homodyne detectors for continuous variable Gaussian states. In…

Quantum Physics · Physics 2009-11-07 M. S. Kim , Jinhyoung Lee , W. J. Munro

We present quantum fidelity benchmarks for continuous-variable (CV) quantum devices to outperform quantum channels which can transmit at most $k$-dimensional coherences for positive integers $k$. We determine an upper bound of an average…

Quantum Physics · Physics 2016-06-06 Ryo Namiki

In this paper we discuss the fidelity of states in infinite dimensional systems, give an elementary proof of the infinite dimensional version of Uhlmann's theorem, and then, apply it to generalize several properties of the fidelity from…

Quantum Physics · Physics 2011-07-05 Jinchuan Hou , Xiaofei Qi

We derive several bounds on fidelity between quantum states. In particular we show that fidelity is bounded from above by a simple to compute quantity we call super--fidelity. It is analogous to another quantity called sub--fidelity. For…

Quantum Physics · Physics 2008-11-19 J. A. Miszczak , Z. Puchała , P. Horodecki , A. Uhlmann , K. Życzkowski

This paper reviews recent advances in quantum learning theory for continuous-variable (CV) systems. Quantum learning theory investigates how to extract classical information from quantum systems as efficiently as possible. CV systems are…

Quantum Physics · Physics 2026-05-11 Francesco Anna Mele

In the theory of quantum transmission of information the concept of fidelity plays a fundamental role. An important class of channels, which can be experimentally realized in quantum optics, is that of Gaussian quantum channels. In this…

Quantum Physics · Physics 2009-10-31 Gh. -S. Paraoanu , H. Scutaru

We present a detailed report on the decoherence of quantum states of continuous variable systems under the action of a quantum optical master equation resulting from the interaction with general Gaussian uncorrelated environments. The rate…

Quantum Physics · Physics 2007-05-23 A. Serafini , M. G. A. Paris , F. Illuminati , S. De Siena

Continuous-variable (CV) cluster states are a universal quantum computing platform that has experimentally out-scaled qubit platforms by orders of magnitude. Room-temperature implementation of CV cluster states has been achieved with…

The fidelity of a quantum transformation is strongly linked with the prior partial information of the state to be transformed. We illustrate this interesting point by proposing and demonstrating the superior cloning of coherent states with…

Quantum Physics · Physics 2009-11-13 Metin Sabuncu , Gerd Leuchs , Ulrik L. Andersen

We derive a computable analytical formula for the quantum fidelity between two arbitrary multimode Gaussian states which is simply expressed in terms of their first- and second-order statistical moments. We also show how such a formula can…

Quantum Physics · Physics 2015-12-23 Leonardo Banchi , Samuel L. Braunstein , Stefano Pirandola

It is shown that the fidelity, a basic notion of quantum information science, may be used to characterize quantum phase transitions, regardless of what type of internal order is present in quantum many-body states. If the fidelity of two…

Statistical Mechanics · Physics 2007-05-23 Huan-Qiang Zhou , John Paul Barjaktarevic

In quantum/wave systems with chaotic classical analogs, wavefunctions evolve in highly complex, yet deterministic ways. A slight perturbation of the system, though, will cause the evolution to diverge from its original behavior increasingly…

Chaotic Dynamics · Physics 2009-11-07 Nicholas R. Cerruti , Steven Tomsovic

The size of the Hilbert space for a multiqubit state scales exponentially with the number of constituent qubits. Often this leads to a similar exponential scaling of the experimental resources required to characterize the state. Contrary to…

Quantum Physics · Physics 2024-05-06 Konstantin Tiurev , Anders S. Sørensen

The entanglement fidelity provides a measure of how well the entanglement between two subsystems is preserved in a quantum process. By using a simple model we show that in some cases this quantity in its original definition fails in the…

Quantum Physics · Physics 2009-11-13 Yang Xiang , Shi-Jie Xiong

Continuous-Variable (CV) devices are a promising platform for demonstrating large-scale quantum information protocols. In this framework, we define a general quantum computational model based on a CV hardware. It consists of vacuum input…

Quantum Physics · Physics 2019-02-06 Tom Douce , Damian Markham , Elham Kashefi , Peter van Loock , Giulia Ferrini

Fidelity estimation for entangled states constitutes an essential building block for quality control and error detection in quantum networks. Nonetheless, quantum networks often encounter heterogeneous and correlated noise, leading to…

Quantum Physics · Physics 2024-11-18 Liangzhong Ruan , Bas Dirkse

Basic properties of Uhlmann's partial fidelities are discussed. Statistical interpretation in terms of POVM measurements is established. Multiplicativity properties are considered. The relationship between partial fidelities and partitioned…

Quantum Physics · Physics 2010-04-05 Alexey E. Rastegin

We present a class of non-Gaussian two-mode continuous variable states for which the separability criterion for Gaussian states can be employed to detect whether they are separable or not. These states reduce to the two-mode Gaussian states…

Quantum Physics · Physics 2016-08-16 Derek McHugh , Vladimír Bužek , Mário Ziman

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…

Quantum Physics · Physics 2009-11-13 Robert Koenig , Michael M. Wolf