Joint Quantum Institute, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Science. 2017 Jun 23;356(6344):1265-1268. doi: 10.1126/science.aag1407.
The act of position measurement alters the motion of an object being measured. This quantum measurement backaction is typically much smaller than the thermal motion of a room-temperature object and thus difficult to observe. By shining laser light through a nanomechanical beam, we measure the beam's thermally driven vibrations and perturb its motion with optical force fluctuations at a level dictated by the Heisenberg measurement-disturbance uncertainty relation. We demonstrate a cross-correlation technique to distinguish optically driven motion from thermally driven motion, observing this quantum backaction signature up to room temperature. We use the scale of the quantum correlations, which is determined by fundamental constants, to gauge the size of thermal motion, demonstrating a path toward absolute thermometry with quantum mechanically calibrated ticks.
位置测量的行为会改变被测量物体的运动。这种量子测量反作用通常比室温物体的热运动小得多，因此难以观察。通过将激光照射通过纳米机械梁，我们测量梁的热驱动振动，并通过光力学力波动以由海森堡测量-干扰不确定性关系决定的水平来干扰其运动。我们展示了一种交叉相关技术，以区分光驱动运动和热驱动运动，在高达室温的情况下观察到这种量子反作用特征。我们利用由基本常数决定的量子相关性的标度来衡量热运动的大小，展示了一种使用量子机械校准标记进行绝对测温的方法。
