Bistability of a slow mechanical oscillator coupled to a laser-driven two-level system

TL;DR

This paper explores the bistability phenomenon in a slow mechanical oscillator strongly coupled to a laser-driven two-level system, revealing new nonlinear behaviors in the regime where the oscillator's frequency is much less than the system's linewidth.

Contribution

It demonstrates the emergence of bistability in a coupled system with slow oscillators and two-level systems, extending understanding of nonlinear dynamics in such quantum-mechanical setups.

Findings

Bistability occurs at strong coupling in slow oscillators.

System behavior resembles optical cavity optomechanics.

Potential for experimental detection of bistability in molecular systems.

Abstract

It has been recently proposed that single molecule spectroscopy could be employed to detect the motion of nano-mechanical resonators. Estimates of the coupling constant (g) between the molecular two-level system and the oscillator indicate that it can reach values much larger than the mechanical resonating pulsation (omega_m) and the two-level system linewidth (Gamma). Other experimental realization of the same system are also approching this strong coupling regim. In this paper we investigate the behavior of the system in the limit for slow mechanical oscillator omega_m << Gamma}. We find that, for sufficiently large coupling, the system undergoes a bistability reminiscent of that observed in optical cavities coupled to mechanical resonators.