Violations of Bell's inequality for Gaussian states with homodyne detection and nonlinear interactions

TL;DR

This paper demonstrates that Bell's inequality violations can be observed in Gaussian states using homodyne detection combined with nonlinear local operations, with robustness against detection inefficiencies.

Contribution

It introduces a method to observe Bell violations in Gaussian states via nonlinear local rotations, expanding the tools for quantum nonlocality tests.

Findings

Bell violations are achievable with Gaussian states using nonlinear operations.

Finite detection efficiency only mildly impacts Bell violation detection.

The approach may extend to entanglement distillation applications.

Abstract

We show that homodyne measurements can be used to demonstrate violations of Bell's inequality with Gaussian states, when the local rotations used for these types of tests are implemented using nonlinear unitary operations. We reveal that the local structure of the Gaussian state under scrutiny is crucial in the performance of the test. The effects of finite detection efficiency is thoroughly studied and shown to only mildly affect the revelation of Bell violations. We speculate that our approach may be extended to other applications such as entanglement distillation where local operations are necessary elements besides quantum entanglement.