# Squeezing phase diffusion

## TL;DR

This paper demonstrates how an optical parametric oscillator can reduce phase diffusion in quantum optical channels, showing both theoretical and experimental results that identify a threshold for effective noise squeezing based on input energy and OPO parameters.

## Contribution

It introduces a method to counteract phase noise in quantum communication using OPOs, with a detailed analysis of the threshold conditions for noise squeezing.

## Key findings

- OPO can squeeze phase noise above a certain threshold
- The threshold depends on input energy and OPO parameters
- Experimental results confirm theoretical predictions

## Abstract

We address the use of optical parametric oscillator (OPO) to counteract phase-noise in quantum optical communication channels, and demonstrate reduction of phase diffusion for coherent signals travelling through a suitably tuned OPO. In particular, we theoretically and experimentally show that there is a threshold value on the phase-noise, above which OPO can be exploited to squeeze phase noise. The threshold depends on the energy of the input coherent state, and on the relevant parameters of the OPO, i.e. gain and input/output and crystal loss rates.