Reducing added-noise in a micro-mechanically mediated electro-optic converter

Bidirectional transduction of microwave and optical fields would be a useful resource in the toolbox of quantum technology. We have demonstrated a mechanically mediated electro-optic converter by coupling a micromechanical oscillator to a microwave circuit and an optical cavity simultaneously. Operating this device at T < 100 mK, we recorded a conversion efficiency of 47% and added noise of 38 photons [1]. While we have realized high efficiency, the added noise is still an order of magnitude too large. Here, we present our efforts to lower the added noise by designing phononic shielding of the mechanics and replacing our superconducting metal with NbTiN.

[1] Higginbotham, A. P., et. al. “Harnessing electro-optic correlations in an efficient mechanical converter,” Nature Physics 14, 1038–1042 (2018)