Quantum and Topological Phononics with Ultrasound Waves on a Chip

ABSTRACT

Phonons hosted by mesoscopic mechanical resonators can be strongly isolated from the environment, enabling coherence times in excess of 100 ms using modern dissipation engineering techniques. Tailored coupling to other quantum systems then allows manipulating the phonons’ quantum state. We have, for example, used a superconducing microwave circuit for coherent control, and an optical interferometer for measurement-based quantum control of phonon modes. Experiments are underway to couple such long-lived phonons to non-linear quantum systems including electron spins and superconducting qubits. These platforms may find applications as quantum transducers and memories. In another line of research, have realized a phononic topological insulator of the valley-Hall kind, in analogy to its photonic counterpart. At its boundary, phonon modes propagate robustly and with ultralow absorption loss (~3 dB/km), thanks again to dissipation engineering. We quantify backscattering and confirm robust propagation even around sharp bends, as long as they satisfy the lattice symmetry. Such phonon waveguides are an elementary building block for low-loss phonon circuits with potential applications in sensing and information processing.

Affiliation: Niels Bohr Insitute, Copenhagen University, Denmark

BIOGRAPHY

Albert Schliesser obtained his PhD in 2009, at the Max-Planck Institute of Quantum Optics under the supervision of T. W. Hänsch. After a postdoc at École Polytechnique Fédérale de Lausanne, he joined the Niels Bohr Institute in Copenhagen, where he became full professor in 2016. With his group he conducts research in the areas of Quantum Optics, Optomechanics, and Hybrid Quantum Systems, pioneering e.g. highly coherent mechanical devices and their quantum control with light and microwaves. He is recipient of the Otto Hahn medal, EPS early career prize, IUPAP Young Scientist Prize, the Danish EliteForsk prize and both a Starting and a Consolidator ERC grant. In 2020 he has been elected Fellow of the Optical Society of America.