Bulletin of the American Physical Society
APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014; Denver, Colorado
Session Y36: Optical Cavites and Optomechanics |
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Sponsoring Units: DAMOP Chair: Kaden Hazzerd, JILA Room: 703 |
Friday, March 7, 2014 8:00AM - 8:12AM |
Y36.00001: Dynamics of a ``Nearly Lightless'' Laser Joshua Weiner, Justin Bohnet, Kevin Cox, Matthew Norcia, James Thompson Bad-cavity (superradiant) lasers using highly forbidden atomic transitions are expected to achieve coherence lengths on the order of the earth-sun distance, potentially improving optical atomic clocks and other precision measurements. We have realized a proof-of-principle cold-atom Raman laser operating deep in the superradiant regime, where the effective atomic linewidth is much narrower than the cavity linewidth. Here we present experimental studies of active and passive sensing of external fields with a superradiant laser, relaxation oscillations, and phase synchronization between two spatially distinct ensembles emitting into a single optical cavity. [Preview Abstract] |
Friday, March 7, 2014 8:12AM - 8:24AM |
Y36.00002: Cavity cooling of free nanoparticles in high vacuum Peter Asenbaum, Stefan Kuhn, Ugur Sezer, Stefan Nimmrichter, Markus Arndt Cavity cooling has been successfully applied to single atoms, ions and atomic ensembles. It is however, most indispensable for larger and more complex particles, where direct laser cooling techniques are not applicable. We demonstrate cavity cooling of a silicon nanoparticle with a reduction of the transverse kinetic energy by a factor of over 30 [Asenbaum, P. et al. Nat. Commun. 4:2743]. Utilizing a pulsed laser we create and launch silicon nanoparticles beneath a high finesse cavity in high vacuum environment. While the particles transit through the intense cavity field the transverse velocity is reduced. By detecting the scattered light from the particle we can trace its movement in real time. Advancing this technique will be crucial to enable quantum coherence experiments with nanoparticles. [Preview Abstract] |
Friday, March 7, 2014 8:24AM - 8:36AM |
Y36.00003: Opto-mechanics with sub-wavelength grating-membranes Haitan Xu, Utku Kemiktarak, Corey Stambaugh, Mathieu Durand, John Lawall, Jacob Taylor We fabricate highly reflective sub-wavelength grating membranes using stoichiometric silicon nitride. We achieve a grating reflectivity of 99.6\% with a membrane mechanical frequency of $\sim$1 MHz. We integrate the grating-membrane into a Fabry-Perot cavity and investigate its opto-mechanical properties. We also consider the prospect of using them for three mode opto-mechanics experiments where the two optical cavity modes are coupled through a mechanical mode. [Preview Abstract] |
Friday, March 7, 2014 8:36AM - 8:48AM |
Y36.00004: Quantum nonlinearity near optomechanical instabilities Xunnong Xu, Michael Gullans, Jacob Taylor We show that is possible to realize significant optomechanical nonlinearities at the few quanta level in strongly driven two-mode optomechanical systems. In particular, as the strength of the driving laser increases the energy of one of the optomechanical normal modes approaches zero and the associated harmonic oscillator length becomes large, which leads to an enhanced nonlinear coupling between this mode and the driven mode. This enhances the intrinsic nonlinearity of the optomechanical coupling by an amount scaling with sidebands resolution. We show that this could be measured in two-photon correlations when the system is in the side-band resolved regime with relatively large single-photon optomechanical coupling. These conditions are within the reach of current devices and especially of optomechanical photonic/phononic crystals. [Preview Abstract] |
Friday, March 7, 2014 8:48AM - 9:00AM |
Y36.00005: Classical oscillators for understanding quantum descriptions of mechanical systems Chiao-Hsuan Wang, Jacob Taylor Optomechanics has been successfully applied to systems involving wide range of scales from as small as $10^{-21}$ g for atomic level objects like cold atoms to as large as $10^3$ g for macroscopic scale systems like LIGO project. As the size of the mechanical object getting larger, more degrees of freedom come in and the quantum harmonic oscillation treatment of optomechanics becomes questionable. We propose models to show that spring-like classical oscillators may occur at large scale, and they describe methods for distinguishing between quantum harmonic oscillations and other oscillatory behavior. [Preview Abstract] |
Friday, March 7, 2014 9:00AM - 9:12AM |
Y36.00006: Quantum synchronization of a driven self-sustained oscillator Christoph Bruder, Andreas Nunnenkamp, Stefan Walter Synchronization is a universal phenomenon that is important both in fundamental studies and in technical applications. Here we investigate synchronization in the simplest quantum-mechanical scenario possible, i.e., a quantum-mechanical self-sustained oscillator coupled to an external harmonic drive [1]. Using the power spectrum we analyze synchronization in terms of frequency entrainment and frequency locking in close analogy to the classical case. We show that there is a step-like crossover to a synchronized state as a function of the driving strength. In contrast to the classical case, there is a finite threshold value in driving. Quantum noise reduces the synchronized region and leads to a deviation from strict frequency locking. [1] S. Walter, A. Nunnenkamp, and C. Bruder, arXiv:1307.7044 [Preview Abstract] |
Friday, March 7, 2014 9:12AM - 9:24AM |
Y36.00007: Oscillator tunneling dynamics in the Rabi model Elinor Irish, Julio Gea-Banacloche The familiar Rabi model (or single-mode spin-boson model), comprising a two-level system coupled to a quantum harmonic oscillator, continues to produce rich and surprising physics when the coupling strength becomes comparable to the individual subsystem frequencies. We construct approximate solutions for the regime in which the oscillator frequency is small compared to that of the two-level system and the coupling strength matches or exceeds the oscillator frequency. Relating our fully quantum calculation to a previous semi-classical approximation, we find that the dynamics of the oscillator can be considered to a good approximation as that of a particle tunneling in a classical double-well potential, despite the fundamentally entangled nature of the joint system. We assess the prospects for observation of oscillator tunneling in the context of nano- or micro-mechanical experiments and find that it should be possible if suitably high coupling strengths can be engineered. [Preview Abstract] |
Friday, March 7, 2014 9:24AM - 9:36AM |
Y36.00008: Linear and nonlinear optomechanics in a cryogenic membrane-in-the-middle system Donghun Lee, Mitchell Underwood, David Mason, Alexey Shkarin, Scott Hoch, Jack Harris In cavity optomechanics, linear optomechanical interactions have been used to readout and cool the motion of mechanical oscillators, while nonlinear interactions have been proposed to study quantum non-demolition measurements of mechanical oscillators and the production of non-Gaussian mechanical states. A membrane-in-the-middle system can provide both types of interactions. In this talk, we will present recent results measured in both linear and nonlinear interaction regimes with a membrane-in-the-middle system operating at 500 mK. Linear coupling in this device enables us to cool the mechanical mode of a SiN membrane at 705 kHz to roughly one phonon. During the cooling measurement, we also observed strong asymmetry between the mechanical sidebands, in agreement with the phonon number inferred from other measurements. We also measured nonlinear optomechanics, in particular the quadratic interaction. With a simple theoretical model, we systematically characterized the classical dynamics arising from this quadratic optomechanical interaction. We expect that by combining quadratic coupling with resolved-sideband laser cooling, this device will be able to explore the aforementioned quantum phenomena. We gracefully acknowledge financial support from AFOSR (No. FA9550-90-1-0484). [Preview Abstract] |
Friday, March 7, 2014 9:36AM - 9:48AM |
Y36.00009: Pattern formation in the synchronization dynamics of arrays of optomechanical oscillators Steven Habraken, Roland Lauter, Christian Brendel, Max Ludwig, Florian Marquardt We consider two-dimensional arrays of coupled optomechanical cells, each of which consists of a laser-driven optical cavity interacting with a mechanical (vibrational) mode. The mechanical modes can be driven in self-sustained oscillations. We study the collective classical non-linear dynamics of the phases of these oscillations, which is described by the well-studied Kuramoto model and optomechanical extensions thereof [1]. The model parameters can be tuned by the laser drives. We focus on pattern formation and find that, depending on the parameters, the phases may or may not synchronize in a stationary configuration of vortex-antivortex pairs. We identify a relevant length scale and find hysteresis associated to the synchronization transition. For some model parameters, this length scale becomes comparable to the lattice spacing, in which case the phase configurations develop structure on smaller and smaller scales and eventually settle into random patterns. Besides, we address the stability and time evolution of binary patterns in which all oscillators are initialized to phases of $0$ or $\pi$.\\ \\ $[1]$ G. Heinrich, M. Ludwig, J. Qian, B. Kubala and F. Marquardt, Phys. Rev. Lett. 107, 043603 (2011). [Preview Abstract] |
Friday, March 7, 2014 9:48AM - 10:00AM |
Y36.00010: Sideband Raman Cooling of Optical Phonons in Semiconductors Jun Zhang, Leong Chuan Kwek, Qihua Xiong Last century has witnessed a tremendous success of laser cooling technology from trapped atomic ions to solid-state optical refrigeration[1,2]. As one of the laser cooling techniques, sideband Raman cooling plays an important role in quantum ground state preparation, coherent quantum-state manipulation and quantum phenomena study. However, those studies still limited in trapped atomic ions and cavity optomechanics, which need be cooled it below than 0.1 Kelvin even tens of nano-Kelvin due to very low frequency of phonons from several kHz to GHz. Here we report sideband Raman cooling and heating experiments of longitudinal optical phonon (LOP) with a 6.23 THz in semiconductor ZnTe nano-ribbons[3]. By using of red-sideband laser, we cool the LOP from 225 to 55 Kelvin, corresponding to an average occupation number reduced from 0.36 to 0.005. We also observe a LOPs heating from 230 to 384 Kelvin with a blue-sideband pumping. Our experiment opens a possibility of all solid state quantum applications using semiconductor optical phonon mediated coupling at room temperature. [1] arxiv, 1303.0733v1 (2013); [2] Nature, 493, 504 (2013); [3] J. Zhang, et. al, sideband Raman cooling of optical phonon in semiconductors, (prepared) [Preview Abstract] |
Friday, March 7, 2014 10:00AM - 10:12AM |
Y36.00011: Squeezing of a mechanical resonator Emma Wollman, Chan U Lei, Aaron Weinstein, Junho Suh, Keith Schwab It is well-known that quantum mechanics places limits on the minimum energy of a harmonic oscillator via the ever-present zero point fluctuations of the quantum ground state. Through squeezing, however, it is possible to decrease the noise of a single motional quadrature below the zero point level. While squeezing below the quantum noise level has been achieved with light, squeezing of the motion of a mechanical resonator below its zero-point fluctuations has yet to be realized. A recent proposal by Kronwald, Marquardt, and Clerk (1) suggests a method of squeezing a single quadrature of the mechanics more than 3dB below the level of its zero point fluctuations. Such squeezing is achievable even if the resonator starts in a thermal state with occupation well above the ground state. We present phase-dependent measurements showing squeezing of mechanics approaching the quantum limit.\\ \\ (1) A. Kronwald, F. Marquardt, and A.A. Clerk. arXiv:1307.5309 (2013). [Preview Abstract] |
Friday, March 7, 2014 10:12AM - 10:24AM |
Y36.00012: Trampoline Resonator Fabrication for Tests of Quantum Mechanics at High Mass Matthew Weaver, Brian Pepper, Petro Sonin, Hedwig Eerkens, Frank Buters, Sven de Man, Dirk Bouwmeester There has been much interest recently in optomechanical devices that can reach the ground state. Two requirements for achieving ground state cooling are high optical finesse in the cavity and high mechanical quality factor. We present a set of trampoline resonator devices using high stress silicon nitride and superpolishing of mirrors with sufficient finesse (as high as 60,000) and quality factor (as high as 480,000) for ground state cooling in a dilution refrigerator. These devices have a higher mass, between 80 and 100 ng, and lower frequency, between 200 and 500 kHz, than other devices that have been cooled to the ground state, enabling tests of quantum mechanics at a larger mass scale. [Preview Abstract] |
Friday, March 7, 2014 10:24AM - 10:36AM |
Y36.00013: Time-Continuous Bell Measurements Sebastian G. Hofer, Denis V. Vasilyev, Markus Aspelmeyer, Klemens Hammerer We combine the concept of Bell measurements, in which two systems are projected into a maximally entangled state, with the concept of continuous measurements, which concerns the evolution of a continuously monitored quantum system. For such time-continuous Bell measurements we derive the corresponding stochastic Schr\"odinger equations, as well as the unconditional feedback master equations. Our results apply to a wide range of physical systems, and are easily adapted to describe an arbitrary number of systems and measurements. Time-continuous Bell measurements therefore provide a versatile tool for the control of complex quantum systems and networks. As examples we show show that (i) two two-level systems can be deterministically entangled via homodyne detection, tolerating photon loss up to 50\%, and (ii) a quantum state of light can be continuously teleported to a mechanical oscillator, which works under the same conditions as are required for optomechanical ground state cooling. [Preview Abstract] |
Friday, March 7, 2014 10:36AM - 10:48AM |
Y36.00014: Real-Space Tailoring of the Electron-Phonon Coupling in Ultra-Clean Nanotube Mechanical Resonators Avishai Benyamini, Assaf Hamo, Silvia Viola Kusminskiy, Felix von Oppen, Shahal Ilani The coupling between electrons and phonons is at the heart of many fundamental phenomena in nature. Despite tremendous advances in controlling electrons or phonons in engineered nanosystems, the control over their coupling is still widely lacking. Here we demonstrate the ability to fully tailor electron-phonon interactions using a new class of suspended carbon nanotube devices, in which we can form highly-tunable single and double quantum dots at arbitrary locations along a nanotube mechanical resonator. We find that electron-phonon coupling can be turned on and off by controlling the position of a quantum dot along the resonator. Using double quantum dots we structure the interactions in real-space to couple specific electronic and phononic modes. This tailored coupling allows measurement of the phonons' spatial parity and imaging of their mode shapes. Finally, we demonstrate coupling between phonons and internal electrons in an isolated system, decoupled from the random environment of the electronic leads, a crucial step towards fully-engineered quantum-coherent electron-phonon systems. [Preview Abstract] |
Friday, March 7, 2014 10:48AM - 11:00AM |
Y36.00015: Detection of the mechanical motion of a carbon nanotube resonator by an adjacent nanotube single-electron-transistor Assaf Hamo, Avishai Binyamini, Shahal Ilani, Felix von Oppen In recent years the detection of nano-mechanical motion of carbon nanotubes has made substantial progress. This enabled the measurement of mechanical coupling to single electrons, improved mass detection to the level of an individual proton, and improved force detection to extremely tiny forces. In all these experiments the nanotube was used both as the mechanical resonator and the detector of its own motion, requiring the nanotube to be in a conducting state and reducing the detection sensitivity due to back-action and mechanical nonlinearities. Here, we demonstrate a detection scheme using a separate detector based on a second nanotube single-electron-transistor, eliminating these limitations. The separation of the detector and the mechanical resonator in our system opens the way to investigation of new nano-mechanical phenomena, inaccessible to date. [Preview Abstract] |
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