Entanglement as a resource for discrimination of classical environments

TL;DR

This paper investigates how quantum probes, especially Gaussian states, can be used to distinguish between local and common classical noise in bipartite harmonic oscillator systems, highlighting the superiority of joint position-quadrature measurements.

Contribution

It introduces discrimination strategies using quantum probes for classical noise environments and demonstrates the optimality of joint position-quadrature measurements with Gaussian states.

Findings

Joint position-quadrature measurement outperforms other homodyne schemes.

Gaussian probes are effective and experimentally friendly for noise discrimination.

The study compares practical measurement strategies with quantum-limited bounds.

Abstract

We address extended systems interacting with classical fluctuating environments and analyze the use of quantum probes to discriminate local noise, described by independent fluctuating fields, from common noise, corresponding to the interaction with a common one. In particular, we consider a bipartite system made of two non interacting harmonic oscillators and assess discrimination strategies based on homodyne detection, comparing their performances with the ultimate bounds on the error probabilities of quantum-limited measurements. We analyze in details the use of Gaussian probes, with emphasis on experimentally friendly signals. Our results show that a joint measurement of the position-quadrature on the two oscillators outperforms any other homodyne-based scheme for any input Gaussian state.