Laser cooling of a nanomechanical oscillator into its quantum ground state

Jasper Chan, Thiago P. Mayer Alegre, Amir H. Safavi-Naeini, Jeff T. Hill, Alex Krause, Simon Gröblacher, Markus Aspelmeyer, Oskar Painter

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(1) and small masses(2). 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(3,4). 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(5,6) or as a means of coupling hybrid quantum systems(7-9). Here we report the development of a coupled, nanoscale optical and mechanical resonator(10) 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.

Quantum Optics, Quantum Nanophysics and Quantum Information
External organisation(s)
California Institute of Technology (Caltech)
No. of pages
Publication date
Peer reviewed
Austrian Fields of Science 2012
103026 Quantum optics, 210006 Nanotechnology, 103025 Quantum mechanics, 203017 Micromechanics
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