Optomechanical studies of a nanobeam coupled to a superconducting microwave cavity
Résumé
The low temperature dissipation in glass nanomechanical resonators is dominated by low energy exci-
tations, i.e., atomic scale entities that are modeled as TLSs (tunneling two level systems). These TLSs
couple to vibrational modes of nanomechanical resonators (NEMS) made of amorphous materials. Probing the mechanical mode in its ground state can give us insight into the microscopic nature of individual TLS. Following up on the work described in [1], here we present optomechanical measurements of the Brownian motion of a mechanical mode. Our 50 m long nanostring made of silicon nitride is capacitively coupled to a Nb microwave cavity. The microwave cavity is pumped at its red or blue mechanical sidebands and we measure the noise at the cavity resonance frequency induced by the mechanical motion. We observe damping or anti-damping of the mechanical mode for red or blue detuning of the pump. When applying a probe tone near the cavity resonance in addition to the pump tone we observe optomechanically induced transparency.
[1] X. Zhou et al., Brute-force cooling and on-chip thermometry for microwave optomechanics,
arXiv:1903.04992v2 (2019).