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  Ground state cooling of an ultracoherent electromechanical system


Yannick Seis (ENS Lyon)


Horaire/Time : Tuesday, 9th May 2023 at 14:00


Lieu/Place : Visio-conférence Zoom hydride depuis Salle Rémy Lemaire K223, Institut Néel

Zoom link : https://univ-grenoble-alpes-fr.zoom.us/j/91808901596?pwd=UWZ2cml2N1VBOEZBenk0d3RJek9rdz09


Résumé/Abstract : Cavity electromechanics relies on parametric coupling between microwave and mechanical modes to manipulate the mechanical quantum state, and provide a coherent interface between different parts of hybrid quantum systems. High coherence of the mechanical mode is of key importance in such applications, in order to protect the quantum states it hosts from thermal decoherence. After an extended introduction to the field of optomechanics, we present the characterisation at millikelvin temperatures of a microwave electro-mechanical system featuring an ultra-coherent phononic-crystal membrane. The mechanical dissipation rate is measured down to 30 mK reaching a Q-factor of 1.5 billion, at 1.485 MHz mode frequency. Then we perform resolved sideband cooling on the mechanical mode, cooling it to its motional ground state nmin = 0.76 ± 0.16. We thus show the operation of an electromechanical system in the quantum regime, where its coherence time is estimated to be ~100 ms. We also show microwave-induced mechanical broadening up to 630 Hz, reaching manipulation speeds on the order of state-of-the-art superconducting qubits coherence times making our device a candidate for microwave quantum memories