Prospects for quantum acoustics with phononic crystal devices

TL;DR

This paper explores the potential of phononic crystal devices for quantum acoustics, demonstrating a method to achieve strong piezoelectric coupling with superconducting circuits, paving the way for nonlinear phononic quantum systems.

Contribution

It provides a general calculation approach for phonon-electron interactions and shows that strong coupling is achievable in nanoscale phononic resonators with superconducting circuits.

Findings

Large piezoelectric coupling rates are possible.

A general recipe for calculating phonon-electron interactions is demonstrated.

Potential for nonlinear single-phonon level quantum systems is suggested.

Abstract

Nanomechanical systems made from phononic crystals can act as highly coherent microwave-frequency circuits at cryogenic temperatures. However, generating sufficient coupling between these devices and microwave superconducting quantum circuits is challenging due to the vastly different length scales of acoustic and electrical excitations. Here we demonstrate a general recipe for calculating these interactions and show that large piezoelectric coupling rates between microwave superconducting circuits containing Josephson junctions and nanoscale phononic resonances are possible, suggesting a route to phononic crystal circuits and systems that are nonlinear at the single-phonon level.