Simultaneous cooling of coupled mechanical resonators in cavity optomechanics

TL;DR

This paper proposes a theoretical scheme to cool two coupled mechanical resonators to their ground state using an optomechanical interface, enabling quantum coherence studies in multi-mode systems.

Contribution

It introduces a novel theoretical method for ground-state cooling of coupled mechanical resonators via an optomechanical interface, including analytical results and extension to resonator chains.

Findings

Ground-state cooling is feasible in the resolved-sideband regime.

Optimal driving conditions are identified for minimal phonon numbers.

Analytical expressions for cooling limits are derived.

Abstract

Quantum manipulation of coupled mechanical resonators has become an important research topic in optomechanics because these systems can be used to study the quantum coherence effects involving multiple mechanical modes. A prerequisite for observing macroscopic mechanical coherence is to cool the mechanical resonators to their ground state. Here we propose a theoretical scheme to cool two coupled mechanical resonators by introducing an optomechanical interface. The final mean phonon numbers in the two mechanical resonators are calculated exactly and the results show that the ground-state cooling is achievable in the resolved-sideband regime and under the optimal driving. By adiabatically eliminating the cavity field in the large-decay regime, we obtain analytical results of the cooling limits, which show the smallest achievable phonon numbers and the parameter conditions under which the optimal cooling is achieved. Finally, the scheme is extended to the cooling of a chain of coupled mechanical resonators.