Violating Bell inequalities with entangled optical frequency combs and multi-pixel homodyne detection

TL;DR

This paper theoretically explores the violation of Bell inequalities using entangled optical frequency combs and multi-pixel homodyne detection, highlighting potential for loophole-free quantum nonlocality tests with complex multimode light sources.

Contribution

It introduces a theoretical framework for testing Bell inequalities with frequency combs and homodyne detection, advancing the understanding of quantum correlations in multimode optical systems.

Findings

Feasible violation of Bell inequalities with frequency combs

Use of high-efficiency homodyne detection to close loopholes

Potential for scalable quantum information processing

Abstract

We have theoretically investigated the possibility of using any of several continuous-variable Bell-type inequalities - for which the dichotomic measurements are achieved with coarse-grained quadrature (homodyne) measurements - in a multi-party configuration where each participant is given a section, in the frequency domain, of the output of an optical parametric oscillator which has been synchronously-pumped with a frequency comb. Such light sources are undergoing intense study due to their novel properties, including the potential for production of light entangled in many hundreds of physical modes - a critical component for many proposals in optical or hybrid-optical quantum computation proposals. The situation we study notably uses only highly-efficient optical homodyne detection, meaning that in such systems the fair-sampling loophole would be relatively easy to avoid.