Two-Dimensional Optomechanical Crystal Cavity with High Quantum Cooperativity

TL;DR

This paper demonstrates a 2D optomechanical crystal resonator with high quantum cooperativity, enabling quantum-coherent interactions at ultralow temperatures for advanced quantum information and sensing applications.

Contribution

It introduces a novel 2D phononic bandgap structure that isolates acoustic modes while facilitating heat removal, achieving quantum cooperativity greater than one at millikelvin temperatures.

Findings

Achieved quantum cooperativity C_eff ≈ 1.3 > 1 under continuous-wave driving.

Utilized a 2D phononic bandgap to isolate acoustic modes and enhance thermal management.

Enabled potential quantum transduction between microwave and optical frequencies.

Abstract

Optomechanical systems offer new opportunities in quantum information processing and quantum sensing. Many solid-state quantum devices operate at millikelvin temperatures -- however, it has proven challenging to operate nanoscale optomechanical devices at these ultralow temperatures due to their limited thermal conductance and parasitic optical absorption. Here, we demonstrate a two-dimensional optomechanical crystal resonator capable of achieving large cooperativity $C$ and small effective bath occupancy $n_b$, resulting in a quantum cooperativity $C_{\text{eff}}\equiv C/n_b \approx 1.3 > 1$ under continuous-wave optical driving. This is realized using a two-dimensional phononic bandgap structure to host the optomechanical cavity, simultaneously isolating the acoustic mode of interest in the bandgap while allowing heat to be removed by phonon modes outside of the bandgap. This achievement paves the way for a variety of applications requiring quantum-coherent optomechanical interactions, such as transducers capable of bi-directional conversion of quantum states between microwave frequency superconducting quantum circuits and optical photons in a fiber optic network.