Nonlocality in Quantum Dynamics

John R. Fanchi

Sandu Popescu

E. Strambini, K. S. Makarenko, G. Abulizi +2 more

Nonlocality is a key feature discriminating quantum and classical physics. Quantum-interference phenomena, such as Young's double slit experiment, are one of the clearest manifestations of nonlocality, recently addressed as dynamical to specify its origin in the quantum equations of motion. It is well known that loss of dynamical nonlocality can occur due to (partial) collapse of the wavefunction due to a measurement, such as which-path detection. However, alternative mechanisms affecting dynamical nonlocality have hardly been considered, although of crucial importance in many schemes for quantum information processing. Here, we present a fundamentally different pathway of losing dynamical nonlocality, demonstrating that the detailed geometry of the detection scheme is crucial to preserve nonlocality. By means of a solid-state quantum-interference experiment we quantify this effect in a diffusive system. We show that interference is not only affected by decoherence, but also by a loss of dynamical nonlocality based on a local reduction of the number of quantum conduction channels of the interferometer. With our measurements and theoretical model we demonstrate that this mechanism is an intrinsic property of quantum dynamics. Understanding the geometrical constraints protecting nonlocality is crucial when designing quantum networks for quantum information processing.

Po‐Wen Chen, Md. Manirul Ali, Shiaw-Huei Chen

Abstract We investigate the transient non-Markovian dynamics of quantum nonlocality for a pair of two-level atoms coupled to a common thermal-squeezed environment. We use Bell-CHSH inequality, steering inequality, and entanglement as theoretical tools to investigate the nonlocality dynamics. We see significant differences between the non-Markovian nonlocality dynamics and its Markovian counterpart. We mainly focus on quantum steering nonlocality which has gained much interest recently. An enhanced quantum nonlocality is shown through the violation of steering inequality and entanglement in the non-Markovian regime of the structured environment. A close correspondence is shown between steering nonlocality and entanglement dynamics.

Andrey Anatoljevich Grib, Waldyr A. Rodrigues

Huai-Xin Lu, Yingde Li

This paper studies the dynamics of nonlocality for a bosonic entangled coherent state in a phase damping model. The density operator of the system is solved by using a superoperator method. The dynamics of nonlocality for the bosonic entangled coherent state is uncovered by the Bell operator based on the pseudospin operator of a light field. The dynamics of the nonlocality for this state has also been studied by other Bell operators. The result of the numerical calculations of the Bell function shows that the quantum nonlocality heavily depends on the chosen Bell operator.