Feedback cooling of a cantilever's fundamental mode below 5 mK.
We cool the fundamental mechanical mode of an ultrasoft silicon cantilever from a base temperature of 2.2 K down to 2.9+/-0.3 mK using active optomechanical feedback. The lowest observed mode temperature is consistent with limits determined by the properties of the cantilever and by the measurement noise. For high feedback gain, the driven cantilever motion is found to suppress or "squash" the optical interferometer intensity noise below the shot noise level.
IBM Research Division, Almaden Research Center, 650 Harry Rd., San Jose California 95120, USA.
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Poggio
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Degen
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HJ
Mamin
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Rugar