Strong coupling at room temperature with a centimeter-scale quartz crystal

TL;DR

This paper demonstrates strong optomechanical coupling at room temperature using a centimeter-scale quartz crystal, advancing quantum information processing and macroscopic quantum studies.

Contribution

It reports achieving and characterizing strong coupling in a bulk acoustic-wave resonator with independent control over power and detuning at room temperature.

Findings

Observation of normal-mode splitting indicating strong coupling

Mechanical linewidth estimated at 7.13 MHz

Single-photon coupling rate of 7.76 Hz

Abstract

Brillouin-based optomechanical systems with high-frequency acoustic modes provide a promising platform for implementing quantum-information processing and wavelength conversion applications, and for probing macroscopic quantum effects. Achieving strong coupling through electrostrictive Brillouin interaction is essential for coupling the massive mechanical mode to an optical field, thereby controlling and characterizing the mechanical state. However, achieving strong coupling at room temperature has proven challenging due to fast mechanical decay rates, which increase the pumping power required to surpass the coupling threshold. Here, we report an optomechanical system with independent control over pumping power and frequency detuning to achieve and characterize the strong-coupling regime of a bulk acoustic-wave resonator. Through spectral analysis of the cavity reflectivity, we identify clear signatures of strong coupling, i.e., normal-mode splitting and an avoided crossing in the detuned spectra, while estimating the mechanical linewidth $\Gamma_m/2\pi~=~7.13MHz$ and the single-photon coupling rate $g_0/2\pi~=~7.76Hz$ of our system. Our results provide valuable insights into the performances of room-temperature macroscopic mechanical systems and their applications in hybrid quantum devices.