Probing the quantum motion of a macroscopic mechanical resonator with a resonant rf-fluxonium
| When |
Jan 05, 2026
from 11:00 to 12:00 |
|---|---|
| Where | Salle des thèses |
| Contact Name | Audrey Bienfait |
| Attendees |
Samuel Deléglise |
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MHz-frequency mechanical resonators are powerful platforms for quantum technologies and tests of fundamental physics, yet efficient control remains challenging due to their low energy scales and the difficulty of coupling them to well-controlled quantum systems at matching frequencies. Here we demonstrate high-fidelity, repeated interactions between a 4-MHz suspended silicon nitride membrane resonator and a resonant superconducting fluxonium qubit. Over the membrane’s 6-ms lifetime, the two systems swap excitations more than 300 times. Using the qubit as a stroboscopic spectrometer, we reconstruct the membrane’s position-noise spectrum, revealing its thermal occupation, qubit-induced back-action, and the characteristic emission–absorption imbalance. This asymmetry directly reflects the non-commutation of phonon ladder operators, demonstrating the quantum character of the long-lived, massive mode. Because the predicted Diósi–Penrose collapse time is comparable to the membrane’s decoherence time, our platform operates in a regime suitable for future interferometric tests of gravity-induced wavefunction collapse.