Measurements of the Degree of Comprehensive Cooling in Stochastically Quenched Microstructures

We clarify the atomistic behavior of a micromechanical structure whose thermally driven stochastic motion has been quenched, using force-feedback techniques. The quenching is observed, via both qualitative and quantitative measurements, to optically clamp one of the vibrational modes of the lever such that the overall body temperature is only reduced slightly. The degree of comprehensive cooling is gauged by examining the reduction in the stochastic vibration of the third vibrational mode of a doubly clamped lever, while the first is quenched, to 143 K. The observation of only slight temperature reductions is confirmed by noting the absence of a phase change in condensing water vapor on a cantilever, although the deflection-magnitude of the fundamental vibrational mode is reduced to an effective temperature of 11 K. Finally, the measured stochastic variation rate is consistent with the lever's mechanical properties, not its thermal properties, demonstrating near-room temperature operation. The results thus imply that each vibrational mode can be reduced to deep sub-Kelvin temperatures independent of the overall thermal state of the lever, thus enabling sub-Brownian sensing in applications such as chemical and radiation detection, and quantum superposition experiments