Low-temperature diamond optomechanics*

Diamond mechanical devices have the potential to serve as a hybrid platform for facilitating quantum interactions between photons, phonons, and the spin and orbital degrees of freedom of embedded defect qubits, such as nitrogen-vacancy (NV) centers, which can couple to mechanical motion via crystal strain. Recent experiments [1,2] have demonstrated hybrid mechanical systems in diamond consisting of nanofabricated mechanical resonators that host coherent NV centers. However, an outstanding challenge to reaching the high-cooperativity regime in these systems, where such applications as phonon-mediated spin-spin interactions and NV-assisted mechanical cooling become realizable, is the demonstration of long-lived, high-strain mechanical modes near their ground state of motion. As a step toward this goal, we design and fabricate single-crystal diamond optomechanical crystals which host GHz-scale mechanical modes with large zero-point strain and characterize them at 6K in a closed-cycle cryostat. We observe optomechanically-driven phonon lasing, optomechanically-induced transparency, and laser cooling of the mechanical motion in these devices.
1. D. Lee, et al., J. Opt. 19 033001 (2017)
2. J. V. Cady, et al., Quantum Sci. Tech. 4 2 (2019)