Kuno Yoshihito
Graduate School of Engineering Science, Akita University, Akita 010-8502, Japan.
J Phys Condens Matter. 2024 Sep 27;36(50). doi: 10.1088/1361-648X/ad7cb4.
Quantum nonlocality is an important concept in quantum physics. In this work, we study the quantum nonlocality in a fermion many-body system under quasi-periodic disorders. The Clauser-Horne-Shimony-Holt (CHSH) inequality is systematically investigated, which quantifies quantum nonlocality between two sites. We find particular behaviors of the quantifiers of quantum nonlocality around the extended and critical phase transitions in the system and further that the CHSH inequality is not broken in the globally averaged picture of the maximum value of the quantum nonlocality, but the violation probability of the CHSH inequality for two site pairs in the system becomes sufficiently finite in the critical phase and on a critical phase boundary. Further, we investigate an extension of the CHSH inequality, Mermin-Klyshko-Svetlichny (MKS) polynomials, which can characterize multipartite quantum nonlocality. We also find a similar behavior to the case of CHSH inequality. In particular, in the critical regime and on a transition point, the adjacent three-qubit MKS polynomial in a portion of the system exhibits a quantum nonlocal violation regime with a finite probability in the critical phase.
量子非定域性是量子物理学中的一个重要概念。在这项工作中，我们研究了准周期无序下费米子多体系统中的量子非定域性。系统地研究了克劳泽 - 霍恩 - 希莫尼 - 霍尔特（CHSH）不等式，该不等式量化了两个位点之间的量子非定域性。我们发现了系统中扩展和临界相变附近量子非定域性量化指标的特殊行为，并且进一步发现，在量子非定域性最大值的全局平均图景中，CHSH不等式并未被违背，但在临界相和临界相边界上，系统中两个位点对的CHSH不等式违背概率变得足够有限。此外，我们研究了CHSH不等式的扩展——默明 - 克利什科 - 斯韦特利奇尼（MKS）多项式，它可以表征多体量子非定域性。我们还发现了与CHSH不等式情况类似的行为。特别是，在临界区域和一个转变点上，系统一部分中的相邻三量子比特MKS多项式在临界相中呈现出具有有限概率的量子非定域违背区域。
