Approaching the Quantum Limit of a Nanomechanical Resonator

By coupling a single-electron transistor to a high-quality factor, 19,7-megahertz nanomechanical resonator, we demonstrate position detection approaching that set by the Heisenberg uncertainty principle limit. At millikelvin temperatures, position resolution a factor of 4,3 above the quantum limit is achieved and demonstrates the near-ideal performance of the single-electron transistor as a linear amplifier. We have observed the resonator's thermal motion at temperatures as low as 56 millikelvin, with quantum occupation factors of N_TH = 58. The implications of this experiment reach from the ultimate limits of force microscopy to qubit readout for quantum information devices.