paper

Quantum Electromechanics on Silicon Nitride Nanomembranes

arXiv:1512.04660 · doi:10.1038/ncomms12396

Abstract

We present a platform based upon silicon nitride nanomembranes for integrating superconducting microwave circuits with planar acoustic and optical devices such as phononic and photonic crystals. Utilizing tensile stress and lithographic patterning of a silicon nitride nanomembrane we are able to reliably realize planar capacitors with vacuum gap sizes down to $s \approx 80$ nm. In combination with spiral inductor coils of micron pitch, this yields microwave ( $\approx 8$ GHz) resonant circuits of high impedance ( $Z_{0} \approx 3.4$ k $I^c ◯$ ) suitable for efficient electromechanical coupling to nanoscale acoustic structures. We measure an electromechanical vacuum coupling rate of $g_{0} /2 I ¨ = 41.5$ ~Hz to the low frequency ( $4.48$ MHz) global beam motion of a patterned phononic crystal nanobeam, and through parametric microwave driving reach a backaction cooled mechanical mode occupancy as low as $n_{m} = 0.58$ .

21 pages, 9 figures