Detecting nonclassicality in randomly-displaced copies of a squeezed state

TL;DR

The paper presents a method to detect quadrature squeezing in quantum states with randomly varying displacements by converting quadrature squeezing into number squeezing using a specific interaction Hamiltonian.

Contribution

It introduces a novel approach that transfers nonclassicality from quadrature to number squeezing, enabling detection despite random displacements.

Findings

Successfully detects squeezing with random displacements

Uses $g^{(2)}(0)<1$ as a nonclassicality criterion

Provides a Hamiltonian-based conversion method

Abstract

We address a fundamental question: Can one determine whether a received signal is squeezed when each copy arrives with a different displacement/amplitude? We introduce an interaction Hamiltonian that converts quadrature squeezing into number squeezing. Using this conversion, we test whether the copies satisfy $g^{(2)}(0)<1$. The Hamiltonian itself does not create nonclassicality; it only transfers it from quadrature squeezing to number squeezing. This allows us to identify squeezing even when individual copies have random displacements.