Quantum acoustics: Quantum mechanics with sound

Speaker: Professor Andrew Cleland
Affiliation: University of Chicago

Abstract

Phonons are the quantum particles of sound waves in solids, representing the collective motion of astronomical numbers of atoms. While initially phonons merely served as a convenience for calculations of properties such as heat capacity or in scattering calculations, developments in a relatively new field termed “quantum acoustics” have shown that phonons can in fact be used as carriers of quantum information, with properties very similar to photons, the quantum particles of light. In this talk I will describe a series of experimental measurements my group has completed that demonstrate the generation, storage, and detection of individual phonons in an acoustic resonator [1]; using phonons to transmit quanta of energy and to support quantum entanglement [2,3], as well as demonstrating a single-phonon interferometer and a somewhat mysterious effect known as “quantum erasure” [4]; and most recently using phonons to demonstrate a fundamental quantum effect first seen with photons, the Hong-Ou-Mandel effect [5,6], which beautifully illustrates the wave-particle duality fundamental to quantum mechanics. These experiments all involve acoustic excitations on the surface of a solid, known as surface acoustic waves, and the generation and detection of individual phonons is performed using superconducting qubits, electronic quantum bits that form the basis of many commercial quantum computing efforts.

[1] K. J. Satzinger et al., “Quantum control of surface acoustic wave phonons”, Nature 563, 661–665 (2018)

[2] A. Bienfait et al., “Phonon-mediated quantum state transfer and remote qubit entanglement”, Science 364, 368-371 (2019)

[3] E. Dumur et al., “Quantum communication with itinerant surface acoustic wave phonons”, npj Quantum Information 7, 1-5 (2021)

[4] A. Bienfait et al., “Quantum erasure using surface acoustic phonons”, Phys. Rev. X 10, 021055 (2020)

[5] C. K. Hong, Z. Y. Ou and L. Mandel, “Measurement of subpicosecond time intervals between two photons by interference,” Phys. Rev. Lett. 59, 2044-2046 (1987)

[6] H. Qiao et al., ”Hong-Ou-Mandel effect with surface acoustic phonons”, unpublished (2023)