Showing papers by "Tobias Donner published in 2009"
TL;DR: This work achieves a displacement measurement with an imprecision below the standard quantum limit scale by measuring the motion of a nanomechanical oscillator with a nearly shot-noise limited microwave interferometer.
Abstract: Nanomechanical oscillators are at the heart of ultrasensitive detectors of force, mass and motion. As these detectors progress to even better sensitivity, they will encounter measurement limits imposed by the laws of quantum mechanics. If the imprecision of a measurement of the displacement of an oscillator is pushed below a scale set by the standard quantum limit, the measurement must perturb the motion of the oscillator by an amount larger than that scale. Here we show a displacement measurement with an imprecision below the standard quantum limit scale. We achieve this imprecision by measuring the motion of a nanomechanical oscillator with a nearly shot-noise limited microwave interferometer. As the interferometer is naturally operated at cryogenic temperatures, the thermal motion of the oscillator is minimized, yielding an excellent force detector with a sensitivity of 0.51 aN Hz(-1/2). This measurement is a critical step towards observing quantum behaviour in a mechanical object.
414 citations
Journal Article•
TL;DR: A cavity optomechanical system in which a collective density excitation of a Bose-Einstein condensate serves as the mechanical oscillator coupled to the cavity field, and the results open up new directions for investigating mechanical oscillators in the quantum regime and the border between classical and quantum physics.
Abstract: Cavity optomechanics studies the coupling between a mechanical oscillator and the electromagnetic field in a cavity. We report on a cavity optomechanical system in which a collective density excitation of a Bose-Einstein condensate serves as the mechanical oscillator coupled to the cavity field. A few photons inside the ultrahigh-finesse cavity trigger strongly driven back-action dynamics, in quantitative agreement with a cavity optomechanical model. We approach the strong coupling regime of cavity optomechanics, where a single excitation of the mechanical oscillator substantially influences the cavity field. The results open up new directions for investigating mechanical oscillators in the quantum regime and the border between classical and quantum physics.
363 citations
TL;DR: In this article, a Bose-Einstein condensate is coupled to a single mode of an ultra-high finesse optical cavity, and the system is governed by strong interactions between the atomic motion and the light field even at the level of single quanta.
Abstract: A Bose–Einstein condensate is dispersively coupled to a single mode of an ultra-high finesse optical cavity. The system is governed by strong interactions between the atomic motion and the light field even at the level of single quanta. While coherently pumping the cavity mode the condensate is subject to the cavity optical lattice potential whose depth depends nonlinearly on the atomic density distribution. We observe optical bistability already below the single photon level and strong back-action dynamics which tunes the coupled system periodically out of resonance.
84 citations
11 Oct 2009
TL;DR: In this paper, the motion of a nanomechanical oscillator with precision beyond the standard quantum limit was measured using a microwave interferometer that operates near the shot-noise limit.
Abstract: We measure the motion of a nanomechanical oscillator with precision beyond the standard quantum limit, by using a microwave interferometer that operates near the shot-noise limit.
1 citations