Quantum jumps of sound

Abstract:Quantum mechanics predicts that a vibrating object's energy comes in discrete packets, yet no measurement of its position reveals this discreteness. Resolving individual energy levels requires a qualitatively different measurement, one coupling to the resonator's energy rather than its displacement. We use a superconducting qubit dispersively coupled to a nanomechanical resonator to perform repeated quantum nondemolition measurements of the phonon number. An aligned transfer-print technique integrating the qubit and resonator yields a mechanical lifetime of $T_1 = 2.1$ milliseconds and a dispersive shift of $2\chi/2\pi = 328$ kilohertz per phonon. We heralded single-phonon states with 85% fidelity and observed quantum jumps between the resonator's first excited state and ground state. These discontinuous transitions are a striking manifestation of quantum mechanics in a massive, vibrating object.

arXiv:2610.10714 [quant-ph]

(or arXiv:2610.10714v1 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2610.10714 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

Takuma Makihara et al., Quantum jumps of sound. Science 393, 1217-1220 (2026)

https://doi.org/10.1126/science.aeh7535 Focus to learn more DOI(s) linking to related resources

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