Towards phonon routing: Controlling propagating acoustic waves in the quantum regime

TL;DR

This paper demonstrates control over propagating surface acoustic waves in the quantum regime using a superconducting qubit, enabling phonon routing with high extinction and fast response times for quantum information applications.

Contribution

It introduces a method to route propagating phonons in the quantum regime by coupling surface acoustic waves with a tunable superconducting qubit, enabling in-flight phonon manipulation.

Findings

Achieved 80% extinction in SAW transmission.

Demonstrated 40 ns routing response time.

Enabled control of short 100 ns phonon pulses.

Abstract

We explore routing of propagating phonons in analogy with previous experiments on photons. Surface acoustic waves (SAWs) in the microwave regime are scattered by a superconducting transmon qubit. The transmon can be tuned on or off resonance with the incident SAW field using an external magnetic field or the Autler-Townes effect, and thus the reflection and transmission of the SAW field can be controlled in time. We observe 80% extinction in the transmission of the low power continuous signal and a 40 ns rise time of the router. The slow propagation speed of SAWs on solid surfaces allows for in-flight manipulations of the propagating phonons. The ability to route short, 100 ns, pulses enables new functionality, for instance to catch an acoustic phonon between two qubits and then release it in a controlled direction.