Invited
Harnessing Phonons at the Mesoscale: From Silicon Lasers to High Frequency Cavity-optomechanics

Abstract: We explore new strategies to shape Brillouin interactions in micron-scale guided-wave systems and macroscopic cavity optomechanical systems for both classical and quantum applications.

In recent years, acoustic phonons have emerged as a powerful resource for signal processing, precision metrology, and quantum information. Phonons are quantum-coherent carriers of information with numerous advantages over their electromagnetic counterparts. These include the ability to guide and store signals in much smaller volumes for longer periods of time. The advantages of phonons multiply when the interactions between phonons, photons, and microwave signals can be shaped to create powerful new hybrid technologies. In this talk, we explore methods for controlling and shaping the interactions between photons and acoustic phonons as the basis for both classical and quantum information processing applications. we begin by describing how traveling-wave photon-phonon coupling can be engineered within silicon-based optomechanical waveguides to realize a range of new optomechanical (Brillouin) interactions systems. We harness these interactions to produce new forms mode cooling, non-reciprocal inter-band coupling, integrated signal processing technologies, and new types amplifiers and laser oscillators for silicon photonics.

Looking beyond silicon photonics, the opportunity for such hybrid interactions become quite intriguing when we consider the untapped potential offered by phonons at cryogenic temperatures. At reduced temperatures, intrinsic sources of phonon dissipation plummet, permitting acoustic phonons to live for an astounding number of cycles in pristine crystalline media. Leveraging these same physical principles, we describe new methods to control of ultra-long-lived phonon modes within bulk acoustic wave resonator geometries using light. We show that these bulk acoustic wave techniques open the door to new forms of cryogenic phonon spectroscopy, precision metrology techniques, and high frequency (10-100 GHz) cavity-optomechanical systems with potential for improved robustness against thermal decoherence as the basis for quantum optomechanical signal processing.