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We propose an innovative method to enhance the detection and protection of quantum entanglement, a cornerstone of quantum mechanics with applications in computing, communication, and beyond. While entanglement can be represented through…

Quantum Physics · Physics 2024-12-17 Haruki Matsunaga , Le Bin Ho

We introduce a new entanglement measure based on optimal entanglement witness. First of all, we show that the entanglement measure satisfies some necessary properties, including zero entanglements for all separable states, convexity,…

Quantum Physics · Physics 2024-02-20 Nan Yang , Jiaji Wu , Xianyun Dong , Longyu Xiao , Jing Wang , Ming Li

Entanglement does not correspond to any observable and its evaluation always corresponds to an estimation procedure where the amount of entanglement is inferred from the measurements of one or more proper observables. Here we address…

Quantum Physics · Physics 2009-11-13 Marco G. Genoni , Paolo Giorda , Matteo G. A. Paris

Entanglement witnesses (EWs) are a collection of observables that can characterize separable states and, experimentally, estimating EWs can verify entangled states. In this work, we show that a fixed measurement setting on a multipartite…

Quantum Physics · Physics 2026-05-29 Jaemin Kim , Anindita Bera , Dariusz Chruściński , Joonwoo Bae

We explore the possibility of entanglement detection in continuous variable systems by entanglement witnesses based on covariance matrices, constructible from random homodyne measurements. We propose new linear constraints characterizing…

Quantum Physics · Physics 2021-01-20 Tatiana Mihaescu , Hermann Kampermann , Giulio Gianfelici , Aurelian Isar , Dagmar Bruss

We introduce a family of entanglement witnesses for continuous variable systems, which rely on the sole assumption that their dynamics is that of coupled harmonic oscillators at the time of the test. Entanglement is inferred from the…

Quantum Physics · Physics 2024-07-31 Pooja Jayachandran , Lin Htoo Zaw , Valerio Scarani

We propose new entanglement measures as the detection performance based on the hypothesis testing setting. We clarify how our measures work for detecting an entangled state by extending the quantum Sanov theorem. Our analysis covers the…

Quantum Physics · Physics 2025-01-08 Masahito Hayashi , Yuki Ito

We propose three criteria for identifying continuous variable entanglement between two many-particle systems with no restrictions on the quantum state of the local oscillators used in the measurements. Mistakenly asserting a coherent state…

Quantum Physics · Physics 2009-11-13 A. J. Ferris , M. K. Olsen , E. G. Cavalcanti , M. J. Davis

In quantum information theory, the reliable and effective detection of entanglement is of paramount importance. However, given an unknown state, assessing its entanglement is a challenging task. To attack this problem, we investigate the…

Quantum Physics · Physics 2015-12-09 Jochen Szangolies , Hermann Kampermann , Dagmar Bruß

We use quantum entanglement witnesses derived from Gaussian operators to study the separable criteria of continuous variable states. We transform the validity of a Gaussian witness to a Bosonic Gaussian channel problem. It follows that the…

Quantum Physics · Physics 2022-08-29 Xiao-yu Chen , Maoke Miao , Rui Yin , Jiantao Yuan

We focus on determining the separability of an unknown bipartite quantum state $\rho$ by invoking a sufficiently large subset of all possible entanglement witnesses given the expected value of each element of a set of mutually orthogonal…

Quantum Physics · Physics 2009-11-13 Lawrence M. Ioannou , Benjamin C. Travaglione

We propose a family of entanglement witnesses and corresponding positive maps that are not completely positive based on local orthogonal observables. As applications the entanglement witness of the $3\times 3$ bound entangled state [P.…

Quantum Physics · Physics 2009-11-10 Sixia Yu , Nai-le Liu

Entanglement in continuous-variable non-Gaussian states provides irreplaceable advantages in many quantum information tasks. However, the sheer amount of information in such states grows exponentially and makes a full characterization…

Multipartite entanglement detection is crucial for the develop of quantum information science and quantum computation, communication, simulation and metrology tasks. In contrast to experiments, where several handreds of qubits have been…

Quantum Physics · Physics 2024-11-06 Xiao-yu Chen

We study the detection of continuous-variable entanglement, for which most of the existing methods designed so far require a full specification of the devices, and we present protocols for entanglement detection in a scenario where the…

Quantum Physics · Physics 2021-05-19 Paolo Abiuso , Stefan Bäuml , Daniel Cavalcanti , Antonio Acín

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…

Quantum Physics · Physics 2009-07-02 Gerardo Adesso , Fabrizio Illuminati

We present an approach to estimate the operational distinguishability between an entangled state and any separable state directly from measuring an entanglement witness. We show that this estimation also implies bounds on a variety of other…

Quantum Physics · Physics 2024-04-01 Liang-Liang Sun , Xiang Zhou , Armin Tavakoli , Zhen-Peng Xu , Sixia Yu

We present a class of entanglement identifiers which has the following experimentally friendly feature: once the expectation value of the identifier exceeds some definite limit, we can conclude the state is entangled, even if not all…

Quantum Physics · Physics 2013-08-22 Wieslaw Laskowski , Marcin Markiewicz , Tomasz Paterek , Ryszard Weinar

We derive a family of entanglement criteria for continuous variable systems based on the R\'enyi entropy of complementary distributions. We show that these entanglement witnesses can be more sensitive than those based on second-order…

Quantum Physics · Physics 2015-05-18 A. Saboia , F. Toscano , S. P. Walborn

Quantum correlations are at the core of the power of quantum information and are necessary to reach a quantum computational advantage. In the context of continuous-variable quantum systems, another necessary ressource for quantum advantages…

Quantum Physics · Physics 2024-07-26 Carlos E. Lopetegui , Mathieu Isoard , Nicolas Treps , Mattia Walschaers
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