Towards Quantum Optomechanics Using Bulk Acoustic Wave Resonators

Superconducting circuits are one of the most sophisticated architectures for quantum information processing to date. Their operation at microwave (MW) frequencies, however, confines these circuits to the base stages of dilution refrigerators. MW-to-optical conversion in the quantum regime could enhance the scalability and range of applications of superconducting circuits, using optical photons as noise-free carriers of quantum information that connect circuits in different refrigerators. This requires a conversion process that is coherent, efficient, and with minimal added noise, which has not been demonstrated yet.

We present our advances in developing a cryogenic cavity optomechanical device based on a bulk-acoustic-wave (BAW) mechanical resonator, which can act as an essential part of a MW-to-optical transducer. Strong coupling to BAWs has been demonstrated both for microwave photons [1] and for optical photons [2]. Building on these works, we are developing an optomechanical system for operation at mK temperatures inside a dilution fridge that is also compatible with coupling to superconducting circuits. We discuss the requirements for such a system, and our progress on meeting these.

[1] Chu et al. (2018) Nature, 563(7733), 666–670
[2] Kharel et al. (2018) Arxiv 1812.06202