Interference-assisted squeezing in fluorescence radiation

TL;DR

This paper investigates how quantum interference in a four-level atom affects the squeezing properties of resonance fluorescence, revealing significant enhancements and degradations depending on system parameters.

Contribution

It provides a detailed analysis of interference-assisted squeezing in fluorescence radiation, including analytical dressed state descriptions and numerical results.

Findings

Quantum interference can enhance steady-state squeezing in fluorescence.

Interference effects depend on driving field strength and detuning.

Spectral squeezing can be degraded by increased decay rates due to interference.

Abstract

The squeezing spectrum of the resonance fluorescence is studied for a coherently driven four-level atom in the Y-type configuration. It is found that the squeezing properties of the fluorescence radiation are modified significantly when quantum interference of the spontaneous decays channels is included. We show a considerable enhancement of steady-state squeezing in spectral components for strong and off-resonant driving fields. The squeezing may be increased in both the inner and outer sidebands of the spectrum depending upon the choice of parameters. We also show that the interference can degrade the spectral squeezing by increasing the decay rates of atomic transitions. An analytical description using dressed states is provided to explain the numerical results.