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arXiv · 1611.00878

Optical probing of mechanical loss of a Si_{3}N_{4} membrane below 100 mK

R. Fischer·N. S. Kampel·G. G. T. Assumpção·P. -L. Yu·K. Cicak·R. W. Peterson·R. W. Simmonds·C. A. Regal
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Abstract

We report on low mechanical loss in a high-stress silicon nitride (Si_{3}N_{4}) membrane at temperatures below 100 mK. We isolate a membrane via a phononic shield formed within a supporting silicon frame, and measure the mechanical quality factor of a number of high-tension membrane modes as we vary our dilution refrigerator base temperature between 35 mK and 5 K. At the lowest temperatures, we obtain a maximum quality factor (Q) of 2.3\times10^{8}, corresponding to a Q-frequency product (QFP) of 3.7\times10^{14} Hz. These measurements complement the recent observation of improved quality factors of Si_{3}N_{4} at ultralow temperatures via electrical detection. We also observe a dependence of the quality factor on optical heating of the device. By combining exceptional material properties, high tension, advanced isolation and clamping techniques, high-stress mechanical objects are poised to explore a new regime of exceptional quality factors. Such quality factors combined with an optical probe at cryogenic temperatures will have a direct impact on resonators as quantum objects, as well as force sensors at mK temperatures.

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R. Fischer, N. S. Kampel, G. G. T. Assumpção, P. -L. Yu, K. Cicak, R. W. Peterson, R. W. Simmonds, C. A. Regal. 2016-11-03. Optical probing of mechanical loss of a Si_{3}N_{4} membrane below 100 mK. https://arxiv.org/abs/1611.00878

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