Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published October 6, 2011 | Supplemental Material
Journal Article Open

Laser cooling of a nanomechanical oscillator into its quantum ground state


The simple mechanical oscillator, canonically consisting of a coupled mass–spring system, is used in a wide variety of sensitive measurements, including the detection of weak forces and small masses. On the one hand, a classical oscillator has a well-defined amplitude of motion; a quantum oscillator, on the other hand, has a lowest-energy state, or ground state, with a finite-amplitude uncertainty corresponding to zero-point motion. On the macroscopic scale of our everyday experience, owing to interactions with its highly fluctuating thermal environment a mechanical oscillator is filled with many energy quanta and its quantum nature is all but hidden. Recently, in experiments performed at temperatures of a few hundredths of a kelvin, engineered nanomechanical resonators coupled to electrical circuits have been measured to be oscillating in their quantum ground state. These experiments, in addition to providing a glimpse into the underlying quantum behaviour of mesoscopic systems consisting of billions of atoms, represent the initial steps towards the use of mechanical devices as tools for quantum metrology or as a means of coupling hybrid quantum systems. Here we report the development of a coupled, nanoscale optical and mechanical resonator formed in a silicon microchip, in which radiation pressure from a laser is used to cool the mechanical motion down to its quantum ground state (reaching an average phonon occupancy number of 0.85±0.08). This cooling is realized at an environmental temperature of 20 K, roughly one thousand times larger than in previous experiments and paves the way for optical control of mesoscale mechanical oscillators in the quantum regime.

Additional Information

© 2011 Nature Publishing Group, a division of Macmillan Publishers Limited. Received: 17 June 2011; Accepted: 16 August 2011; Published online: 05 October 2011. This work was supported by the DARPA/MTO ORCHID program through a grant from the AFOSR, the European Commission (MINOS, QUESSENCE), the European Research Council (ERC QOM), the Austrian Science Fund (CoQuS, FOQUS, START) and the Kavli Nanoscience Institute at the California Institute of Technology. The authors thank B. Baker for help with the cryostat set-up, J.C. thanks R. Li, and J.C. and A.H.S.-N. acknowledge support from NSERC. Author Contributions: J.C., T.P.M.A. and A.H.S.-N. designed the device, and J.C. fabricated it with support from J.T.H. J.C., T.P.M.A., A.H.S.-N., J.T.H., A.K. and S.G. performed the measurements and analysed the measured data. O.P. and M.A. supervised the measurements and the data analysis. All authors contributed to the writing of the manuscript.

Attached Files

Supplemental Material - nature10461-s1.pdf


Files (762.2 kB)
Name Size Download all
762.2 kB Preview Download

Additional details

August 22, 2023
October 24, 2023