Ultralow-dissipation micro-oscillator for quantum optomechanics

Optics Express, 2009

Confining a laser field between two high reflectivity mirrors of a high-finesse cavity can increase the probability of a given cavity photon to be scattered by an atom traversing the confined photon mode 1 . This enhanced coupling between light and atoms is successfully employed in cavity quantum electrodynamics experiments and led to a very prolific research in quantum optics 2,3 . The idea of extending such experiments to sub-wavelength sized nanomechanical systems has been recently proposed 4 in the context of optical cavity cooling 5,6 . Here we present an experiment involving a single nanorod consisting of about 10 9 atoms precisely positioned to plunge into the confined mode of a miniature high finesse Fabry-Pérot cavity. We show that the optical transmission of the cavity is affected not only by the static position of the nanorod but also by its vibrational fluctuation. While an imprint of the vibration dynamics is directly detected in the optical transmission, back-action of the light field is also anticipated to quench the nanorod Brownian motion 4 . This experiment shows the first step towards optical cavity controlled dynamics of mechanical nanostructures and opens up new perspectives for sensing and manipulation of optomechanical nanosystems.

Physical Review Letters, 2016

We report the experimental observation of two-mode squeezing in the oscillation quadratures of a thermal micro-oscillator. This effect is obtained by parametric modulation of the optical spring in a cavity opto-mechanical system. In addition to stationary variance measurements, we describe the dynamic behavior in the regime of pulsed parametric excitation, showing enhanced squeezing effect surpassing the stationary 3dB limit. While the present experiment is in the classical regime, our technique can be exploited to produce entangled, macroscopic quantum opto-mechanical modes.

Applied Physics Express, 2015

We theoretically studied the conditions for optomechanical coupling and input laser power to the deep ground-state cooling of a high-finesse optical microcavity-based oscillator and achieved a quantum number of 0.01 (99% in the ground state). An equation predicting a fifth-order multistability is derived, and we see that maximal coupling collinearly depends on laser power and is limited by the cavity decay rate; therefore, a minimum quantum number is achieved at very low decay rates in comparison to recent experimental results. This result will be helpful in engineering extremely low noise optical microcavities with negligible heat absorption for use in high-performance quantum information processing. https://doi.org/10.7567/APEX.8.032801

Europhysics Letters (EPL), 2018

Cavity optomechanics provides a unique platform for controlling micromechanical systems by means of optical fields that cross the classical-quantum boundary to achieve solid foundations for quantum technologies. Currently, optomechanical resonators have become promising candidates for the development of precisely controlled nano-motors, ultrasensitive sensors and robust quantum information processors. For all these applications, a crucial requirement is to cool the mechanical resonators down to their quantum ground states. In this paper, we present a novel cooling scheme to further cool a micromechanical resonator via the noise squeezing effect. One quadrature in such a resonator can be squeezed to induce enhanced fluctuations in the other, “heated” quadrature, which can then be used to cool the mechanical motion via conventional optomechanical coupling. Our theoretical analysis and numerical calculations demonstrate that this squeeze-and-cool mechanism offers a quick technique for deeply cooling a macroscopic mechanical resonator to an unprecedented temperature region below the zero-point fluctuations.

2009

Confining a laser field between two high reflectivity mirrors of a high-finesse cavity can increase the probability of a given cavity photon to be scattered by an atom traversing the confined photon mode. This enhanced coupling between light and atoms is successfully employed in cavity quantum electrodynamics experiments and led to a very prolific research in quantum optics. The idea

Research Square (Research Square), 2023

We address the creation of squeezed states of a mechanical resonator in a hybrid quantum system consisting of two quantum wells placed inside a cavity with a moving end mirror pumped by bichromatic laser fields. The exciton mode and mechanical resonator interact indirectly via microcavity fields. Under the conditions of the generated coupling, we predict squeezing of the mechanical-mode beyond the resolved side-band regime with available experimental parameters. Finally, we show that the squeezing of the mechanical mode is robust against the phonon thermal bath temperature. This work has been supported by Khalifa University through project no. 8474000358 (FSU-2021-018).

Interferometry is a ubiquitous method for sensitive displacement measurements. In typical inter-ferometry employing a coherent state, the amplitude and phase quantum fluctuations are both at the shot noise level. Recently optomechanical systems have been developed that not only measure mechanical motion, but can also manipulate the motion with radiation pressure. For example, radiation forces have been used to cool mechanical resonators to near their quantum ground state [1, 2]. With sufficiently strong radiation pressure, quantum fluctuations can become the dominant mechanical driving force, leading to correlations between the mechanical motion and the quantum fluctuations of the optical field [4]. Such correlations can be used to suppress fluctuations on an interferometer's output optical field below the shot noise level [2, 3], at the expense of increasing fluctuations in an orthogonal quadrature. This method of manipulating the quantum fluctuations is termed ponderomotive [6] squeezing. Here, we observe ponderomotive squeezing at 1.7±0.2 dB below (32% below) the shot noise level and optical amplification of quantum fluctuations by over 25 dB. The squeezing is realized on light transmitted through a Fabry-Perot interferometer with an embedded mechanically compliant dielectric membrane.

Nature Photonics, 2008

Cavity-enhanced radiation-pressure coupling of optical and mechanical degrees of freedom gives rise to a range of optomechanical phenomena, in particular providing a route to the quantum regime of mesoscopic mechanical oscillators. A prime challenge in cavity optomechanics has however been to realize systems which simultaneously maximize optical finesse and mechanical quality. Here we demonstrate for the first time independent control over both mechanical and optical degree of freedom within one and the same on-chip resonator. The first direct observation of mechanical normal mode coupling in a micromechanical system allows for a quantitative understanding of mechanical dissipation. Subsequent optimization of the resonator geometry enables intrinsic material loss limited mechanical Q-factors, rivalling the best values reported in the high MHz frequency range, while simultaneously preserving the resonators' ultra-high optical finesse. Besides manifesting a complete understanding of mechanical dissipation in microresonator based optomechanical systems, our results provide an ideal setting for cavity optomechanics.

Physical Review A, 2009

We present the optical and mechanical properties of high-Q fused silica microtoroidal resonators at cryogenic temperatures (down to 1.6 K). A thermally induced optical multistability is observed and theoretically described; it serves to characterize quantitatively the static heating induced by light absorption. Moreover the influence of structural defect states in glass on the toroid mechanical properties is observed and the resulting implications of cavity optomechanical systems on the study of mechanical dissipation discussed.

Physical Review Letters, 2014

We report the confinement of an optomechanical micro-oscillator in a squeezed thermal state, obtained by parametric modulation of the optical spring. We propose and implement an experimental scheme based on parametric feedback control of the oscillator, which stabilizes the amplified quadrature while leaving the orthogonal one unaffected. This technique allows us to surpass the-3dB limit in the noise reduction, associated to parametric resonance, with a best experimental result of-7.4dB. In a moderately cooled system, our technique can be efficiently exploited to produce strong squeezing of a macroscopic mechanical oscillator below the zero-point motion.