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Related papers: Bell inequality violation on small NISQ computers

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Recently, it was demonstrated by Son et al., Phys. Rev. Lett. \textbf{102}, 110404 (2009), that a separable bipartite continuous variable quantum system can violate the Clauser-Horne-Shimony-Holt (CHSH) inequality via operationally local…

Quantum Physics · Physics 2013-05-29 Mark S. Williamson , Libby Heaney , Wonmin Son

Quantum computing is an information processing paradigm that uses quantum-mechanical properties to speedup computationally hard problems. Although promising, existing gate-based quantum computers consist of only a few dozen qubits and are…

Quantum Physics · Physics 2021-08-26 Ramin Ayanzadeh , Poulami Das , Swamit S. Tannu , Moinuddin Qureshi

We describe a simple experimental setting where joint measurements performed on a single (classical or quantum) entity can violate both the Bell-CHSH inequality and the marginal laws (also called no-signaling conditions). Once emitted by a…

Quantum Physics · Physics 2021-09-09 Diederik Aerts , Massimiliano Sassoli de Bianchi

Today's Noisy Intermediate-Scale Quantum (NISQ) computers have scientific value, but quantum machines with broad practical value must be protected against noise using quantum error correction and fault-tolerant protocols. Recent studies of…

Quantum Physics · Physics 2025-03-13 John Preskill

The inherent noise in current Noisy Intermediate-Scale Quantum (NISQ) devices presents a major obstacle to the accurate implementation of quantum algorithms such as the Variational Quantum Eigensolver (VQE) for quantum chemistry…

Quantum computers promise considerable speedups over classical approaches, which has raised interest from many disciplines. Since any currently available implementations suffer from noise and imperfections, achieving concrete speedups for…

Emerging Technologies · Computer Science 2023-08-16 Felix Greiwe , Tom Krüger , Wolfgang Mauerer

Quantum correlations may violate the Bell inequalities. Most of the experimental schemes confirming this prediction have been realized in all-optical Bell tests suffering from the detection loophole. Experiment which closes this loophole…

Quantum Physics · Physics 2011-09-23 Magdalena Stobińska , Pavel Sekatski , Adam Buraczewski , Nicolas Gisin , Gerd Leuchs

The problem of closing the detection loophole with asymmetric systems, such as entangled atom-photon pairs, is addressed. We show that, for the Bell inequality I_3322, a minimal detection efficiency of 43% can be tolerated for one of the…

Quantum Physics · Physics 2009-11-13 Nicolas Brunner , Nicolas Gisin , Valerio Scarani , Christoph Simon

A common experimental strategy for demonstrating non-classical correlations is to show violation of a Bell inequality by measuring a continuously emitted stream of entangled photon pairs. The measurements involve the detection of photons by…

Quantum Physics · Physics 2015-03-11 Emanuel Knill , Scott Glancy , Sae Woo Nam , Kevin Coakley , Yanbao Zhang

The characterization of a quantum system can be complicated by non-ideal measurement processes. In many systems, the underlying physical measurement is only sensitive to a single fixed state, complementary outcomes are inferred by…

Quantum Physics · Physics 2014-12-24 Kaila C. S. Hall , Daniel K. L. Oi

Today's Noisy Intermediate-Scale Quantum (NISQ) computers support only limited sets of available quantum gates and restricted connectivity. Therefore, quantum algorithms must be transpiled in order to become executable on a given NISQ…

Quantum Physics · Physics 2023-04-13 Yanjun Ji , Sebastian Brandhofer , Ilia Polian

Imperfect detection efficiency remains one of the major obstacles in achieving loophole-free Bell tests over long distances. At the same time, the challenge of establishing a common reference frame for measurements becomes more pronounced…

Quantum Physics · Physics 2025-07-21 Paweł Cieśliński , Tamás Vértesi , Mateusz Kowalczyk , Wiesław Laskowski

Quantum computing is advancing rapidly, yet substantial gaps separate today's noisy intermediate-scale quantum (NISQ) devices from tomorrow's fault-tolerant application-scale quantum (FASQ) machines. We identify four related hurdles along…

Quantum Physics · Physics 2026-05-22 Jens Eisert , John Preskill

Given a pair of isolated devices that accept random binary inputs and return binary outputs, a user can deduce from the observed data alone if the underlying mechanism can be explained classically. Bell's theorem further states that a…

Quantum Physics · Physics 2026-05-21 Kuntal Sengupta , Lewis Wooltorton

Bell's theorem shows that local realistic theories place strong restrictions on observable correlations between different systems, giving rise to Bell's inequality which can be violated in experiments using entangled quantum states. Bell's…

With the surge of quantum computing platforms that continue to push the boundaries of capabilities of noisy intermediate-scale quantum computers, there is a growing interest in finding relevant applications and quantifying the corresponding…

We computationally investigate the complete polytope of Bell inequalities for 2 particles with small numbers of possible measurements and outcomes. Our approach is limited by Pitowsky's connection of this problem to the computationally hard…

Quantum Physics · Physics 2023-03-23 Daniel Collins , Nicolas Gisin

Noise in quantum hardware remains the biggest roadblock for the implementation of quantum computers. To fight the noise in the practical application of near-term quantum computers, instead of relying on quantum error correction which…

Quantum Physics · Physics 2021-10-14 Zhenyu Cai

Noisy Intermediate-Scale Quantum (NISQ) technology will be available in the near future. Quantum computers with 50-100 qubits may be able to perform tasks which surpass the capabilities of today's classical digital computers, but noise in…

Quantum Physics · Physics 2018-08-08 John Preskill

In the current era of Noisy Intermediate-Scale Quantum (NISQ) technology, the practical use of quantum computers remains inhibited by our inability to aptly decouple qubits from their environment to mitigate computational errors. In this…

Quantum Physics · Physics 2022-05-09 Thomas J. Maldonado , Johannes Flick , Stefan Krastanov , Alexey Galda