Time-delayed quantum coherent Pyragas feedback control of photon squeezing in a degenerate parametric oscillator

TL;DR

This paper demonstrates how time-delayed quantum coherent Pyragas feedback control can modulate the squeezing of the output field in a degenerate parametric oscillator, offering a measurement-free method to control quantum states.

Contribution

It introduces a novel application of time-delayed Pyragas feedback control to quantum squeezing in a degenerate parametric oscillator, showing how feedback parameters influence squeezing.

Findings

Time-delayed feedback can enhance quantum squeezing.

Feedback parameters control the degree of squeezing.

Quantum coherence is preserved through measurement-free control.

Abstract

Quantum coherent feedback control is a measurement-free control method fully preserving quantum coherence. In this paper we show how time-delayed quantum coherent feedback can be used to control the degree of squeezing in the output field of a cavity containing a degenerate parametric oscillator. We focus on the specific situation of Pyragas-type feedback control where time-delayed signals are fed back directly into the quantum system. Our results show how time-delayed feedback can enhance or decrease the degree of squeezing as a function of time delay and feedback strength.