A pair of conjugate observables, such as the quadrature amplitudes of harmonic motion, have fundamental fluctuations that are bound by the Heisenberg uncertainty relation. However, in a squeezed quantum state, fluctuations of a quantity can be reduced below the standard quantum limit, at the cost of increased fluctuations of the conjugate variable. Here we prepare a nearly macroscopic moving body, realized as a micromechanical resonator, in a squeezed quantum state. We obtain squeezing of one quadrature amplitude 1.1±0.4 dB below the standard quantum limit, thus achieving a long-standing goal of obtaining motional squeezing in a macroscopic object.
Pirkkalainen, J-M., Damskägg, E., Brandt, M., Massel, F., & Sillanpää, M. (2015). Squeezing of Quantum Noise of Motion in a Micromechanical Resonator. Physical Review Letters, 115(24), 1-15. . https://doi.org/10.1103/PhysRevLett.115.243601