Hybrid nonlocality via atom photon interactions with and without impurities

TL;DR

This paper introduces a hybrid measurement scheme to demonstrate nonlocality in atom-photon systems, analyzing Bell violations under ideal and disordered conditions within cavity QED, and explores the link between Wigner negativity and nonlocality.

Contribution

It proposes a novel hybrid measurement approach for Bell tests in atom-photon systems and studies its robustness under disorder and imperfections.

Findings

Hybrid measurement scheme successfully demonstrates Bell violations in cavity QED.

Disorder in atom-cavity coupling leads to saturation of Bell violation, unlike oscillatory behavior in ordered systems.

Connection between Wigner negativity and hybrid nonlocality is examined.

Abstract

To obtain Bell statistics from hybrid systems composed of finite- and infinite-dimensional systems, we propose a hybrid measurement scheme, in which the continuous mode is measured using the generalized pseudospin operators, while the finite (two)-dimensional system is measured in the usual Pauli basis. Maximizing the Bell expression with these hybrid measurement settings leads to the violations of local realism in hybrid system which is referred to as hybrid nonlocality. We demonstrate the utility of our strategy in a realistic setting of cavity quantum electrodynamics, where an atom interacts resonantly with a single mode of an electromagnetic field under the Jaynes-Cummings Hamiltonian. We dynamically compute the quenched averaged value of hybrid nonlocality in imperfect situations by incorporating disorder in the atom-cavity coupling strength. In the disordered case, we introduce two kinds of measurement scenarios to determine the Bell statistics -- in one situation, experimentalists can tune the optimal settings according to the interaction strength while such controlled power is absent in the other case. In contrast to the oscillatory behavior observed in the ordered case, the quenched averaged violation saturates to a finite value in some parameter regimes in the former case. We also examine the connection between Wigner negativity and hybrid nonlocality.