Pulsed Optomechanics with Microfabricated High-Overtone Bulk Acoustic Wave Resonators

Microfabricated high-overtone bulk acoustic wave resonators (μHBARs) provide a robust solid-state platform for realizing quantum control of high-frequency mechanical excitations. These systems exhibit exceptional thermal anchoring and negligible optical absorption, enabling efficient photon–phonon coupling and long-lived mechanical modes under cryogenic operation. Building upon our recent demonstration of ground-state laser cooling of ultra-massive (7.5 μg) acoustic modes [1], we investigate the temporal dynamics of key processes such as thermal repopulation and laser-induced cooling in this platform using pulsed optomechanical protocols. By applying precisely timed optical cooling pulses followed by time-resolved thermometry, we aim to quantify phonon population decay, coherence times, and the recovery dynamics that govern quantum state stability. Access to this pulsed regime provides a new experimental understanding for exploring non-stationary optomechanical interactions, offering insight into transient phonon dynamics and establishing the foundation for controllable, time-domain quantum operations and long-lived storage protocols in bulk acoustic systems.



[1] Diamandi et al. Optomechanical control of long-lived bulk acoustic phonons in the quantum regime. Nat. Phys. 21, 1482–1488 (2025)