29 research outputs found
Quantum optomechanics in tripartite systems
Owing to their long-lifetimes at cryogenic temperatures, mechanical
oscillators are recognized as an attractive resource for quantum information
science and as a testbed for fundamental physics. Key to these applications is
the ability to prepare, manipulate and measure quantum states of mechanical
motion. Through an exact formal solution to the Schrodinger equation, we show
how tripartite optomechanical interactions, involving the mutual coupling
between two distinct optical modes and an acoustic resonance enables quantum
states of mechanical oscillators to be synthesized and interrogated.Comment: 8 pages, 4 figure
Optomechanical cooling in a continuous system
Radiation-pressure-induced optomechanical coupling permits exquisite control
of micro- and mesoscopic mechanical oscillators. This ability to manipulate and
even damp mechanical motion with light---a process known as dynamical
backaction cooling---has become the basis for a range of novel phenomena within
the burgeoning field of cavity optomechanics, spanning from dissipation
engineering to quantum state preparation. As this field moves toward more
complex systems and dynamics, there has been growing interest in the prospect
of cooling traveling-wave phonons in continuous optomechanical waveguides.
Here, we demonstrate optomechanical cooling in a continuous system for the
first time. By leveraging the dispersive symmetry breaking produced by
inter-modal Brillouin scattering, we achieve continuous mode optomechanical
cooling in an extended 2.3-cm silicon waveguide, reducing the temperature of a
band of traveling-wave phonons by more than 30 K from room temperature. This
work reveals that optomechanical cooling is possible in macroscopic linear
waveguide systems without an optical cavity or discrete acoustic modes.
Moreover, through an intriguing type of wavevector-resolved phonon
spectroscopy, we show that this system permits optomechanical control over
continuously accessible groups of phonons and produces a new form of
nonreciprocal reservoir engineering. Beyond this study, this work represents a
first step towards a range of novel classical and quantum traveling-wave
operations in continuous optomechanical systems.Comment: Manuscript with supplementary information. 17 pages, 4 Figures. Minor
correction in Fig.
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Spontaneous forward Brillouin scattering in carbon disulfide
In recent years, guided acoustic wave Brillouin scattering has become an important tool in photonics, serving as the basis for everything from new forms of information processing to silicon lasers. Due to low losses and long interaction lengths, fiber optic systems offer an intriguing platform to harness these guided-wave light-sound interactions. However, within typical fiber optic systems these interactions are exceedingly weak—requiring complex microstucturing to yield appreciable light-sound coupling. Here, we enhance this light-sound coupling by using a CS2-filled liquid core optical fiber. Owing to tight confinement of the optical and acoustic modes within the fiber core, as well as the large electrostrictive response of CS2, this system yields an unprecedented forward Brillouin gain for a fiber optic system. To demonstrate this physics, we measure multipeaked spontaneous forward Brillouin scattering power spectra, yielding information about the fiber geometry, material properties, and acousto-optic coupling strength. To interpret these data, we simulate the spontaneous Brillouin scattering power spectrum for this fiber system. These results reveal that hybridized acoustic excitations within the fiber core and cladding produce this characteristic multipeaked power spectrum. In the future, the large forward Brillouin coupling, long interaction lengths, and low losses of liquid-core fibers may enable new forms of distributed sensing, lasers with customizable emission, and physics including continuum optomechanical cooling.Air Force Office of Scientific Research (AFOSR) [FA9550-15-1-0389]This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
Oscillator-field model of moving mirrors in quantum optomechanics
We present a microphysics model for the kinematics and dynamics of optomechanics describing the coupling between an optical field, modeled here by a massless scalar field, and the internal and mechanical degrees of freedom of a movable mirror. Instead of implementing boundary conditions on the field, we introduce an internal degree of freedom and its dynamics to describe the mirror's reflectivity. Depending on parameter values, the internal degrees of freedom of the mirror in this model capture a range of its optical activities, from those exhibiting broadband reflective properties to those reflecting only in a narrow band. After establishing the model we show how appropriate parameter choices lead to other well-known optomechanical models, including those of Barton and Calogeracos [Ann. Phys. (NY) 238, 227 (1995)], Calogeracos and Barton, Ann. Phys. (NY) 238, 268 (1995), Law [Phys. Rev. A 51, 2537 (1995)], and Golestanian and Kardar [Phys. Rev. Lett. 78, 3421 (1997); Phys. Rev. A 58, 1713 (1998)]. As a simple illustrative application we derive classical radiation pressure cooling from this model. We then connect our microphysics model to the common descriptions of a moving mirror coupled to radiation pressure (e.g., with
N
x
coupling, where
N
is the photon number and
x
is the mirror displacement), making explicit the underlying assumptions made in these phenomenological models. Our model is also applicable to the lesser explored case of small
N
, which existing models based on sideband approximations [Kimble et al., Phys. Rev. D 65, 022002 (2001)] have not addressed. Interestingly, we also find that slow-moving mirrors in our model can be described by the ubiquitous Brownian motion model of quantum open systems. The scope of applications of this model ranges from a full quantum-mechanical treatment of radiation pressure cooling and quantum entanglement between macroscopic mirrors to the back reaction of Hawking radiation on black-hole evaporation in a moving mirror analog
Nonequilibrium Casimir-Polder Force in Non-Stationary Systems
Recently the Casmir-Polder force felt by an atom near a substrate under
nonequilibrium stationary conditions has been studied theoretically with
macroscopic quantum electrodyanamics (MQED) and verified experimentally with
cold atoms. We give a quantum field theory derivation of the Langevin equation
describing the atom's motion based on the influence functional method valid for
fully nonequilibrium (nonstationary) conditions. The noise associated with the
quantum field derived from first principles is generally colored and nonlocal,
which is at variance with the `local source hypothesis' of MQED's
generalization to nonequilibrium conditions. Precision measurements on the
shape deformation of an atomic gas as a function of its distance from a mirror
would provide a direct check of our predictions based on this Langevin
equation.Comment: Rewritten Introduction and Abstract in v2 with a slightly altered
title to place a sharper focus of our goals and a clearer distinction of what
the influence functional method can achieve beyond the macroscopic QED
approach. The rest of the paper and the results remain the sam
Non-local double-path Casimir phase in atom interferometers
We present a quantum open system theory of atom interferometers evolving in
the quantized electromagnetic field bounded by an ideal conductor. Our
treatment reveals an unprecedented feature of matter-wave propagation, namely
the appearance of a non-local double-path phase coherence. Such a non-local
phase arises from the coarse-graining over the quantized electromagnetic field
and internal atomic degrees of freedom, yielding a non-Hamiltonian evolution of
the atomic waves moving in presence of correlated quantum dipole and field
fluctuations. We develop a diagrammatic interpretation of this phase, and
estimate it for realistic experimental parameters.Comment: 5 pages, 1 figure. Final version, published in the Europhysics
Letter