Laser cooling of high temperature oscillator by multi-level system

TL;DR

This paper investigates laser cooling of a mechanical oscillator coupled to a three-level system, revealing how different configurations affect cooling efficiency and the potential for lasing at high temperatures.

Contribution

It extends standard cooling analysis to high-temperature regimes and compares Ladder and EIT cooling schemes, highlighting their behaviors beyond the Lamb-Dicke regime.

Findings

Ladder-system cooling rate degrades at large classical motion.

EIT cooling maintains negative cooling rate at high motional excitation.

Oscillator can exhibit both cooling and lasing behaviors at steady state.

Abstract

We study the laser cooling of a mechanical oscillator through the coupling with a dissipative three-level system. Under a background temperature beyond the Lamb-Dicke regime, we extend the standard cooling analysis by separately studying the classical motion and the quantum dynamics of the oscillator. In Ladder-system cooling, the cooling rate degrades by orders of magnitude at large classical motion. This phenomenon causes a critical transition of the final temperature at a hot background. In stark contrast, electromagnetic-induced-transparency (EIT) cooling with a $\Lambda$-system produces significant negative cooling rate at high motional excitation. At steady state, the oscillator could exhibit both cooling and lasing behaviours. We argue that a successful EIT cooling requires either a poor quality oscillator to suppress the lasing effect, or terminating the cooling process at a transient stage.