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Quantum squeezing of motion in a mechanical resonator
Wollman, E. E.,Lei, C. U.,Weinstein, A. J.,Suh, J.,Kronwald, A.,Marquardt, F.,Clerk, A. A.,Schwab, K. C. American Association for the Advancement of Scienc 2015 Science Vol.349 No.6251
<P><B>Manipulation of a quantum squeeze</B></P><P>The uncertainty principle of quantum mechanics dictates that even when a system is cooled to its ground state, there are still fluctuations. This zero-point motion is unavoidable but can be manipulated. Wollman <I>et al.</I> demonstrate such manipulation with the motion of a micrometer-sized mechanical system. By driving up the fluctuations in one of the variables of the system, they are able to squeeze the other related variable below the expected zero-point limit. Quantum squeezing will be important for realizing ultrasensitive sensors and detectors.</P><P><I>Science</I>, this issue p. 952</P><P>According to quantum mechanics, a harmonic oscillator can never be completely at rest. Even in the ground state, its position will always have fluctuations, called the zero-point motion. Although the zero-point fluctuations are unavoidable, they can be manipulated. Using microwave frequency radiation pressure, we have manipulated the thermal fluctuations of a micrometer-scale mechanical resonator to produce a stationary quadrature-squeezed state with a minimum variance of 0.80 times that of the ground state. We also performed phase-sensitive, back-action evading measurements of a thermal state squeezed to 1.09 times the zero-point level. Our results are relevant to the quantum engineering of states of matter at large length scales, the study of decoherence of large quantum systems, and for the realization of ultrasensitive sensing of force and motion.</P>