Generation of Large Amplitude Phonon States in Quantum Acoustics

TL;DR

This paper demonstrates the generation of large amplitude phonon states in quantum acoustics using a superconducting qubit coupled to a high-overtone resonator, advancing quantum information and fundamental physics research.

Contribution

It introduces a method to generate large phonon populations in quantum acoustic systems, including observations of extended qubit ringdowns and phonon quenching effects.

Findings

Successful generation of large phonon states confirmed by qubit ringdowns

Observation of an upper threshold behavior due to phonon quenching

Provides a new tool for arbitrary phonon state generation in quantum acoustics

Abstract

The development of quantum acoustics has enabled the cooling of mechanical objects to their quantum ground state, generation of mechanical Fock-states, and Schrodinger cat states. Such demonstrations have made mechanical resonators attractive candidates for quantum information processing, metrology, and macroscopic tests of quantum mechanics. However, generating large-amplitude phonon states in quantum acoustic systems has been elusive. In this work, a single superconducting qubit coupled to a high-overtone bulk acoustic resonator is used to generate a large phonon population in an acoustic mode of a high-overtone resonator. We observe extended ringdowns of the qubit, confirming the generation of a large amplitude phonon state, and also observe an upper threshold behavior, a consequence of phonon quenching predicted by our model. This work provides a key tool for generating arbitrary phonon states in circuit quantum acoustodynamics, which is important for fundamental and quantum information applications.