Bell correlations at finite temperature

2018/05/31 by Matteo Fadel, Jordi Tura
Computer Science · Mathematics · Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Bell state #Bell test experiments #Bell's theorem #Harmonic oscillator #Mathematics #Multipartite #Operator (biology) #Physics #Quantum #Quantum Information and Cryptography #Quantum entanglement #Quantum many-body systems #Quantum mechanics #Quantum nonlocality #Qubit #Schrödinger's cat #Spin (aerodynamics) #quant-ph

paper · pdf · doi:10.22331/q-2018-11-19-107

published as Quantum 2, 107 (2018) · 9 pages (7 + Appendix), 2 figures. Version accepted for publication in Quantum

arxiv created 2018/11/16 · openalex publication_date 2018/11/19 · arxiv updated 2018/11/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We show that spin systems with infinite-range interactions can violate at thermal equilibrium a multipartite Bell inequality, up to a finite critical temperature<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>T</mml:mi><mml:mi>c</mml:mi></mml:msub></mml:math>. Our framework can be applied to a wide class of spin systems and Bell inequalities, to study whether nonlocality occurs naturally in quantum many-body systems close to the ground state. Moreover, we also show that the low-energy spectrum of the Bell operator associated to such systems can be well approximated by the one of a quantum harmonic oscillator, and that spin-squeezed states are optimal in displaying Bell correlations for such Bell inequalities.

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