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arXiv · 1209.2730

Cryogenic Optomechanics with a Si3N4 Membrane and Classical Laser Noise

A. M. Jayich·J. C. Sankey·K. Borkje·D. Lee·C. Yang·M. Underwood·L. Childress·A. Petrenko·S. M. Girvin·J. G. E. Harris
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Abstract

We demonstrate a cryogenic optomechanical system comprising a flexible Si3N4 membrane placed at the center of a free-space optical cavity in a 400 mK cryogenic environment. We observe a mechanical quality factor Q > 4 x 10^6 for the 261-kHz fundamental drum-head mode of the membrane, and a cavity resonance halfwidth of 60 kHz. The optomechanical system therefore operates in the resolved sideband limit. We monitor the membrane's thermal motion using a heterodyne optical circuit capable of simultaneously measuring both of the mechanical sidebands, and find that the observed optical spring and damping quantitatively agree with theory. The mechanical sidebands exhibit a Fano lineshape, and to explain this we develop a theory describing heterodyne measurements in the presence of correlated classical laser noise. Finally, we discuss the use of a passive filter cavity to remove classical laser noise, and consider the future requirements for laser cooling this relatively large and low-frequency mechanical element to very near its quantum mechanical ground state.

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A. M. Jayich, J. C. Sankey, K. Borkje, D. Lee, C. Yang, M. Underwood, L. Childress, A. Petrenko, S. M. Girvin, J. G. E. Harris. 2012-09-12. Cryogenic Optomechanics with a Si3N4 Membrane and Classical Laser Noise. https://doi.org/10.1088/1367-2630%2F14%2F11%2F115018

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