Study of quantum entanglement and Bell’s theory

Yong Du, Xiao-Gang He, Chia-Wei Liu +1 more

Abstract We present our new findings on how various fundamental interactions decisively shape quantum entanglement and the Bell measure within and beyond the quantum field theory (QFT). In QFT, parity symmetry plays a key role in determining entanglement. Parity-conserving interactions produce maximally entangled bipartite systems, while maximally parity-violating interactions result in disentangled bipartite systems, placing the Bell measure on the boundary between classical and quantum theories. By examining the relation between quantum entanglement and Bell measure, we find that clean signals for interactions beyond QFT may be obtained. We propose methods to test these potential signals. Furthermore, we highlight the previously overlooked influence of magnetic fields within detectors, which radically alters predictions for quantum entanglement and Bell nonlocality. This environmental effect induces spurious P and charge-parity (CP) violations, which has to be carefully accounted for to reveal the true P, CP, and Bell nonlocality effects.

G. Fano, S. M. Blinder

Kaifeng Bu, Asutosh Kumar, Junde Wu

Bell inequality is a mathematical inequality derived using the assumptions of locality and realism. Its violation guarantees the existence of quantum correlations in a quantum state. Bell inequality acts as an entanglement witness in the sense that a pure bipartite quantum state, having nonvanishing entanglement, always violates a Bell inequality. We construct Bell-type inequalities for product states in quantum coherence theory for different measures of coherence, and find that the maximally entangled states violate these inequalities. We further show that Bell-type inequalities for relative entropy of coherence is violated by all two-qubit pure entangled states, serving as an entanglement witness.

Kaifeng Bu, Junde Wu

Bell inequality is a mathematical inequality derived using the assumptions of locality and realism. Its violation guarantees the existence of quantum correlations in a quantum state. Bell inequality acts as an entanglement witness in the sense that a pure bipartite quantum state, having nonvanishing entanglement, always violates a Bell inequality. We construct Bell-type inequalities for product states in quantum coherence theory for different measures of coherence, and find that the maximally entangled states violate these inequalities. We further show that Bell-type inequalities for relative entropy of coherence is violated by all two-qubit pure entangled states, serving as an entanglement witness.

Aditi Sen