Simultaneous ground-state cooling of multiple degenerate mechanical modes through cross-Kerr effect

TL;DR

This paper proposes a scalable method using cross-Kerr nonlinearity to overcome dark mode effects, enabling simultaneous ground-state cooling of multiple degenerate mechanical modes in optomechanical systems.

Contribution

The authors introduce a universal scheme employing cross-Kerr effects to break dark mode effects, allowing for scalable simultaneous cooling of multiple mechanical modes.

Findings

Achieves up to four stable steady states with CK effect

Identifies optimal CK coupling strength and laser power for cooling

Extends method to multiple modes with multiple CK effects

Abstract

Simultaneous ground-state cooling of multiple degenerate mechanical modes is a tough issue in optomechanical system due to the existence of the dark mode effect. Here we propose a universal and scalable method to break the dark mode effect of two degenerate mechanical modes by introducing the cross-Kerr (CK) nonlinearity. At most four stable steady states can be achieved in our scheme in the presence of the CK effect, different from the bistable behavior of the standard optomechanical system. Under the constant input laser power, the effective detuning and mechanical resonant frequency can be modulated by the CK nonlinearity, which results in an optimal CK coupling strength for cooling. Similarly, there will be an optimal input laser power for cooling when the CK coupling strength stays fixed. Our scheme can be extended to break the dark mode effect of multiple degenerate mechanical modes by introducing more than one CK effects. To fulfill the requirement of the simultaneous ground-state cooling of N multiple degenerate mechanical modes N-1 CK effects with different strengths are needed. Our proposal provides new insights in dark mode control and might pave the way to manipulating of multiple quantum states in macroscopic system.