Bell's inequality violation by dynamical Casimir photons in a superconducting microwave circuit

TL;DR

This paper demonstrates how Bell's inequality violations can be observed using dynamical Casimir photons in a superconducting microwave circuit, considering realistic noise and loss conditions.

Contribution

It provides an analytical framework for observing Bell violations in a circuit QED setup with dynamical Casimir radiation, including effects of noise, asymmetry, and loss.

Findings

Bell violation observable up to 40 mK temperature

Bell violation persists with up to 65% signal loss

Analytical expressions for Bell operator expectation values

Abstract

We study the Bell's inequality violation by dynamical Casimir radiation with pseudospin measurement. We consider a circuit quantum electrodynamical set-up where a relativistically moving mirror is simulated by variable external magnetic flux in a SQUID terminating a superconducting-microwave waveguide. We analytically obtain expectation values of the Bell operator optimized with respect to channel orientations, in terms of the system parameters. We consider the effects of local noise in the microwave field modes, asymmetry between the field modes resulting from nonzero detuning, and signal loss. Our analysis provides ranges of the above experimental parameters for which Bell violation can be observed. We show that Bell violation can be observed in this set-up up to 40 mK temperature as well as up to 65 % signal loss.