Reconfigurable quantum phononic circuits via piezo-acoustomechanical interactions

TL;DR

This paper demonstrates how piezoelectric strain can be used to reconfigure quantum phononic circuits, enabling large phase shifts, programmable interferometers, and reconfigurable memories with high quantum fidelity.

Contribution

It introduces a novel piezo-acoustomechanical phase shifter and integrates it into quantum phononic circuits for reconfigurable quantum information processing.

Findings

Achieved +/- pi phase shifts for GHz phonons in tens of microns with tens of volts.

Designed programmable multi-mode interferometers for linear phononic processing.

Developed a reconfigurable phononic memory with over 90% quantum state transfer fidelity.

Abstract

We show that piezoelectric strain actuation of acoustomechanical interactions can produce large phase velocity changes in an existing quantum phononic platform: aluminum nitride on suspended silicon. Using finite element analysis, we demonstrate a piezo-acoustomechanical phase shifter waveguide capable of producing +/- pi phase shifts for GHz frequency phonons in 10s of microns with 10s of volts applied. Then, using the phase shifter as a building block, we demonstrate several phononic integrated circuit elements useful for quantum information processing. In particular, we show how to construct programmable multi-mode interferometers for linear phononic processing and a dynamically reconfigurable phononic memory that can switch between an ultra-long-lifetime state and a state strongly coupled to its bus waveguide. From the master equation for the full open quantum system of the reconfigurable phononic memory, we show that it is possible to perform "read" and "write" operations with over 90% quantum state transfer fidelity for an exponentially decaying pulse.