Corralling phonons with light - Jack Sankey

Mechanical technology is everywhere, from the accelerometers and electronic filters in smartphones to ultrasensitive force detectors at the atomic level. The most sensitive devices -- now routinely operating in the quantum regime -- often owe their low noise to the acoustic shielding provided by "phononic crystals" (periodic mechanical structures) surrounding them. Until recently, these systems were built by deliberately adding structural defects to the crystal. Here we present a different paradigm, starting with a perfect crystal and then using the mechanical properties of light to disrupt its periodicity. This creates a single, optically programmable defect mode with highly adjustable mechanical properties. In particular, we can now smoothly control the spatial profile and inertial mass of a single mode, transforming a vibration from one spanning the entire crystal to one gathered into just a few unit cells around the light. This speedy, reversible, all-optical control gives us a brand new way to engineer mechanical systems with on-the-fly reconfigurability. The concept naturally extends to programmable dimers, phononic waveguides, lattices, and more, vastly expanding the ways in which light can redirect mechanical motion. We also find a collective enhancement in this system that may provide a new route toward large-scale quantum motion.

Bio: Jack Sankey studied spin transfer and nanomagnetism at Cornell for a PhD and optomechanics at Yale as a postdoc, before joining McGill in 2012 as the Tier II CRC of Experimental Optomechanics (2012-2022). In 2013, he was awarded a Sloan Fellowship for his work in Optomechanics, and now holds the MacDonald Chair of Physics at McGill (2025-2030). These days, he and Prof. Lilian Childress co-lead the Quantum Optics and Sensing Lab at McGill, studying quantum optomechanics, dark matter, diamond quantum optics, acoustic vision, and (with Prof. Shirin Enger) quantum-limited medical sensors.


The event is sponsored by Quantum City.