Microscopic Theory of Squeezed Light in Quantum Dot Systems

TL;DR

This paper develops a cavity-QED theoretical framework for generating and analyzing squeezed light from semiconductor quantum dots in microcavities, identifying conditions for significant squeezing with low pump power.

Contribution

It introduces a comprehensive quantum theory for squeezed light generation in QD microcavities, highlighting the role of four-wave mixing quantum correlations.

Findings

Achieves up to 5 dB squeezing with ~1 μW pump power.

Identifies conditions for amplitude-quadrature squeezing in QD systems.

Shows quantum correlations influence gain spectrum and squeezing.

Abstract

We present a cavity-QED theory for generating squeezed light from semiconductor quantum dots (QDs) integrated in microcavities. We formulate equations of motion for an inhomogeneously broadened QD ensemble that is incoherently pumped and simultaneously driven by a coherent seed field, solve for steady states, and compute the output-field quadrature variances. The analysis identifies operating conditions that yield amplitude-quadrature squeezing, with photon-number fluctuations reduced below the coherent-state limit and squeezing levels as large as 5 dB attainable with presently accessible QD and cavity parameters using only ~ 1 uW pump power. We further show that quantum correlations originating from four-wave mixing play a dual role: they both shape the gain spectrum and generate squeezing. These correlations constitute the quantum counterpart of the mean-field (semiclassical) mechanisms responsible for self-mode-locking in QD lasers and the ultra-narrow lasing linewidths achieved under self-injection locking.