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Experimental tests of Bell's inequality allow to distinguish quantum mechanics from local hidden variable theories. Such tests are performed by measuring correlations of two entangled particles (e.g. polarization of photons or spins of…

Quantum entanglement plays a vital role in many quantum information and communication tasks. Entangled states of higher dimensional systems are of great interest due to the extended possibilities they provide. For example, they allow the…

In this note we wish to demonstrate that the concept of efficiency loophole, as far as a local realistic model is concerned, is a self-defeating one since it implies that the static fields (for example, electric or gravitational) of and…

General Physics · Physics 2007-05-23 M. R. Mahdavi

The observation that violating Bell inequalities with high probability is possible even when the local measurements are randomly chosen, as occurs when local measurements cannot be suitably calibrated or the parties do not share a common…

Quantum Physics · Physics 2013-08-06 Esteban S. Gómez , Gustavo Cañas , Johanna F. Barra , Adán Cabello , Gustavo Lima

We present a detailed analysis of the Bell measurement scheme proposed in [Phys. Rev. Lett. 114, 113603 (2015)] based on a logical qubit using Greenberger-Horne-Zeilinger (GHZ) entanglement of photons. The success probability of the…

Quantum Physics · Physics 2015-12-02 Seung-Woo Lee , Kimin Park , Timothy C. Ralph , Hyunseok Jeong

An alternative method of detection-loophole-free Bell test is proposed using local hidden variable (LHV) models with optimal detection efficiencies. A framework for constructing such optimal LHV models is presented. Optimal LHV models for…

Quantum Physics · Physics 2015-03-24 Fuming Wang

We propose a feasible optical setup allowing for a loophole-free Bell test with efficient homodyne detection. A non-gaussian entangled state is generated from a two-mode squeezed vacuum by subtracting a single photon from each mode, using…

Quantum Physics · Physics 2009-11-10 R. Garcia-Patron Sanchez , J. Fiurasek , N. J. Cerf , J. Wenger , R. Tualle-Brouri , Ph. Grangier

We show that hybrid local measurements combining homodyne measurements and photodetection provide violations of a Bell inequality with arbitrarily low photodetection efficiency. This is shown in two different scenarios: when one part…

The violation of Bell inequalities where both detection and locality loopholes are closed is crucial for device independent assessments of quantum information. While of technological nature, the simultaneous closing of both loopholes still…

Quantum Physics · Physics 2015-06-17 Colin Teo , Jiří Minář , Daniel Cavalcanti , Valerio Scarani

We derive tight quadratic inequalities for all kinds of hybrid separable-inseparable $n$-particle density operators on an arbitrary dimensional space. This methodology enables us to truly derive a tight quadratic inequality as tests for…

Quantum Physics · Physics 2009-11-07 Koji Nagata , Masato Koashi , Nobuyuki Imoto

The violation of a Bell inequality is an experimental observation that forces one to abandon a local realistic worldview, namely, one in which physical properties are (probabilistically) defined prior to and independent of measurement and…

Although our understanding of Bell's theorem and experimental techniques to test it have improved over the last 40 years, thus far all Bell tests have suffered at least from the detection or the locality loophole. Most photonic Bell tests…

Quantum Physics · Physics 2015-02-19 Falk Töppel , Magdalena Stobińska

According to recent reports, the last loopholes in testing Bell's inequality are closed. It is argued that the really important task in this field has not been tackled yet and that the leading experiments claiming to close locality and…

Quantum Physics · Physics 2007-05-23 L. Vaidman

The demonstration and use of nonlocality, as defined by Bell's theorem, rely strongly on dealing with non-detection events due to losses and detector inefficiencies. Otherwise, the so-called detection loophole could be exploited. The only…

Quantum Physics · Physics 2016-01-20 Gilles Pütz , Nicolas Gisin

Bell inequality tests based on high-dimensional entanglement usually require measurements that can resolve multiple possible outcomes. However, the implementation of high-dimensional multi-outcome measurements is often only emulated via a…

We consider the entanglement between two internal states of a single atom and two photon number states describing either the vaccum or a single photon and thus containing, on average, less than one photon. We show that this intriguing…

Quantum Physics · Physics 2015-05-30 N. Sangouard , J. -D. Bancal , N. Gisin , W. Rosenfeld , P. Sekatski , M. Weber , H. Weinfurter

An experimental scheme is proposed to test Bell's inequality by using superconducting nanocircuits. In this scheme, quantum entanglement of a pair of charge qubits separated in a sufficient long distance may be created by cavity quantum…

Quantum Physics · Physics 2009-11-10 Guang-Ping He , Shi-Liang Zhu , Z. D. Wang , Hua-Zhong Li

Applications such as Device-Independent Quantum Key Distribution (DIQKD) require loophole-free certification of long-distance quantum correlations. However, these distances remain severely constrained by detector inefficiencies and…

Quantum Physics · Physics 2025-04-25 Anubhav Chaturvedi , Marcin Pawłowski , Máté Farkas

The demonstration and use of nonlocality, as defined by Bell's theorem, rely strongly on dealing with non-detection events due to losses and detectors' inefficiencies. Otherwise, the so-called detection loophole could be exploited. The only…

Quantum computational experiments exploiting Noisy Intermediate-Scale Quantum (NISQ) devices to demonstrate violation of a Bell inequality are proposed. They consist of running specified quantum algorithms on few-qubit computers. If such a…

Quantum Physics · Physics 2020-09-02 H. W. L. Naus , H. Polinder