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According to usual definitions, entangled states cannot be given a separable decomposition in terms of products of local density operators. If we relax the requirement that the local density operators be positive, then an entangled quantum…

Quantum Physics · Physics 2015-10-28 Hussain Anwar , Sania Jevtic , Oliver Rudolph , Shashank Virmani

We propose a new method for detecting entanglement of two qubits and discuss its relation with the Clauser-Horne-Shimony-Holt (CHSH) Bell inequality. Without the need for full quantum tomography for the density matrix we can experimentally…

Quantum Physics · Physics 2007-05-23 Kai Chen , Ling-An Wu

Quantum entanglement, after playing a significant role in the development of the foundations of quantum mechanics, has been recently rediscovered as a new physical resource with potential commercial applications such as, for example,…

Quantum Physics · Physics 2009-11-07 Pawel Horodecki , Artur Ekert

Instantaneous measurements of non-local observables between space-like separated regions can be performed without violating causality. This feat relies on the use of entanglement. Here we propose novel protocols for this task and the…

Quantum Physics · Physics 2015-05-20 Salman Beigi , Robert Koenig

We present the generalized state-dependent entropic uncertainty relations in multiple measurements setting, and the optimal lower bound is obtained by considering different measurement sequences. We then apply this uncertainty relation to…

Quantum Physics · Physics 2023-06-05 Li-Hang Ren , Yun-Hao Shi , Jin-Jun Chen , Heng Fan

It is a specific type of quantum correlated state that achieves optimal precision in parameterestimation under unitary encoding. We consider the potential experimental limitation on probe entanglement, and find a relation between achievable…

Quantum Physics · Physics 2026-01-06 Debarupa Saha , Ujjwal Sen

The quantum vacuum has long been known to be characterized by field correlations between spacetime points. These correlations can be swapped with a pair of particle detectors, modelled as simple two-level quantum systems (Unruh-DeWitt…

High Energy Physics - Theory · Physics 2020-10-29 Matthew P. G. Robbins , Laura J. Henderson , Robert B. Mann

We show that a bound impurity in a Bose-Einstein condensate can be directly mapped to an Unruh-DeWitt detector interacting with a relativistic quantum field. We provide explicit experimental parameters for an implementation using…

Quantum Physics · Physics 2026-02-03 T. Rick Perche , Francesco Gozzini , Markus K. Oberthaler

Quantum entanglement is an indispensable resource for many significant quantum information processing tasks. Thus, distilling more entanglement from less entangled resource is a task of practical significance and has been investigated for…

Quantum Physics · Physics 2024-01-18 Zhaofeng Su , Nina Sukhodoeva

Quantum entanglement harvesting in the relativistic setup attracted a lot of attention in recent times. Acquiring more entanglement within two qubits may be very desirable to establish fruitful communication between them. On the other hand…

General Relativity and Quantum Cosmology · Physics 2023-10-17 Dipankar Barman , Bibhas Ranjan Majhi

We introduce two families of criteria for detecting and quantifying the entanglement of a bipartite quantum state of arbitrary local dimension. The first is based on measurements in mutually unbiased bases and the second is based on…

Quantum Physics · Physics 2023-11-08 Simon Morelli , Marcus Huber , Armin Tavakoli

An important problem in quantum information theory is to understand what makes entangled quantum systems non-local or hard to simulate efficiently. In this work we consider situations in which various parties have access to a restricted set…

Quantum Physics · Physics 2014-12-19 Hussain Anwar , Sania Jevtic , Oliver Rudolph , Shashank Virmani

In this paper, I provide a formal set of assumptions and give a natural criterion for a quantum field theory to admit particles. I construct a na\"ive approach to localization for a free bosonic quantum field theory and show how this…

Mathematical Physics · Physics 2010-07-06 David Philip Schroeren

We present a completely localized solution to the problem of entanglement degradation in non-inertial frames. A two mode squeezed state is considered from the viewpoint of two observers, Alice (inertial) and Rob (accelerated), and a model…

Quantum Physics · Physics 2014-05-29 Andrzej Dragan , Jason Doukas , Eduardo Martin-Martinez

Measuring an entangled state of two particles is crucial to many quantum communication protocols. Yet Bell state distinguishability using a finite apparatus obeying linear evolution and local measurement is theoretically limited. We extend…

Quantum Physics · Physics 2011-09-09 N. Pisenti , C. P. E. Gaebler , T. W. Lynn

Unruh-DeWitt detectors interacting locally with a quantum field are systems under consideration for relativistic quantum information processing. In most works, the detectors are assumed to be point-like and, therefore, couple with the same…

Quantum Physics · Physics 2014-05-05 Antony R. Lee , Ivette Fuentes

A set of orthogonal product states of a composite Hilbert space is genuinely nonlocal if the states are locally indistinguishable across any bipartition. In this work, we construct a minimal set of party asymmetry genuine nonlocal set in…

Quantum Physics · Physics 2025-08-21 Atanu Bhunia , Indrani Chattopadhyay , Debasis Sarkar

Bell nonlocality plays a fundamental role in quantum theory. Numerous tests of the Bell inequality have been reported since the ground-breaking discovery of the Bell theorem.Up to now, however, most discussions of the Bell scenario have…

Quantum Physics · Physics 2018-11-08 Meng-Jun Hu , Zhi-Yuan Zhou , Xiao-Min Hu , Chuan-Feng Li , Guang-Can Guo , Yong-Sheng Zhang

Experimental detection of entanglement certainly disturbs the underlying shared state. It is possible that the entanglement content of the system is lost in the process of its detection. This observation has led to the study of sequential…

Quantum Physics · Physics 2022-08-18 Chirag Srivastava , Mahasweta Pandit , Ujjwal Sen

Given a bipartite quantum state rho with subsystems A and B of arbitrary dimensions, we study the entanglement detecting capabilities of locally noneffective, or cyclic, unitary operations [L. B. Fu, Europhys. Lett., vol. 75, pp. 1-7,…

Quantum Physics · Physics 2009-12-21 Sevag Gharibian , Hermann Kampermann , Dagmar Bruss