Squeezing of a two-level system due to classical phase noisy laser

Abstract

Based on the Heisenberg uncertainty relation and the entropy uncertainty relation, the nonclassical effects described by variance squeezing and entropy squeezing for a two-level system driven by a classical phase noisy laser are investigated. Analytical expressions of the variance squeezing and entropy squeezing subjected to the classical phase noisy laser are derived. Our results show that the nonclassical squeezed effects can be protected for a long time in both the Markovian and non-Markovian regions by controlling the ratios between the phase diffusion rate and the system-laser coupling strength. Besides, we also develop an effective strategy to enhance the nonclassical squeezed effects with the help of filtering operation. The underlying physical mechanism to enhance the squeezing is also analyzed.