Systems with coupled mechanical and optical or electrical degrees of freedom1, 2 have fascinating dynamics that, through macroscopic manifestations of quantum behaviour3, provide new insights into the transition between the classical and quantum worlds. Of particular interest is the back-action of electrons and photons on mechanical oscillators, which can lead to cooling and amplification of mechanical motion4, 5, 6. Furthermore, feedback, which is naturally associated with back-action, has been predicted to have significant consequences for the noise of a detector coupled to a mechanical oscillator7, 8. Recently it has also been demonstrated that such feedback effects lead to strong coupling between single-electron transport and mechanical motion in carbon nanotube nanomechanical resonators9, 10. Here we present noise measurements which show that the mesoscopic back-action of electrons tunnelling through a radio-frequency quantum point contact11 causes driven vibrations of the host crystal. This effect is a remarkable macroscopic manifestation of microscopic quantum behaviour, where the motion of a mechanical oscillator—the host crystal, which consists of on the order of 1020 atoms—is determined by statistical fluctuations of tunnelling electrons.
Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755, USA
M. P. Blencowe &
A. J. Rimberg
Rice Quantum Institute, Rice University, Houston, Texas 77005, USA
Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
Bell Laboratories, Alcatel–Lucent, Murray Hill, New Jersey 07974, USA
Loren Pfeiffer &
K. W. West
A.J.R. initiated the project. M.T. fabricated and measured sample A. J.S. fabricated and measured five samples including samples B and C. F.P., M.B., J.Z. and W.X. fabricated and measured two additional samples. L.P. and K.W.W. grew the GaAs/AlGaAs heterostructure material. A.J.R. and M.P.B. developed the theoretical model used to describe the system. M.T. analysed data for sample A. A.J.R. and J.S. analysed data for all samples and co-wrote the paper with input from M.P.B.