2,722 research outputs found
Rotational cavity optomechanics
We theoretically examine the optomechanical interaction between a rotating
nanoparticle and an orbital angular momentum-carrying optical cavity mode.
Specifically, we consider a dielectric nanosphere rotating uniformly in a
ring-shaped optical potential inside a Fabry-Perot resonator. The motion of the
particle is probed by a weak angular lattice, created by introducing two
additional degenerate Laguerre-Gaussian cavity modes carrying equal and
opposite orbital angular momenta. We demonstrate that the rotation frequency of
the nanoparticle is imprinted on the probe optical mode, via the Doppler shift,
and thus may be sensed experimentally using homodyne detection. We show
analytically that the effect of the optical probe on the particle rotation
vanishes in the regime of linear response, resulting in an accurate frequency
measurement. We also numerically characterize the degradation of the
measurement accuracy when the system is driven in the nonlinear regime. Our
results are relevant to rotational Doppler velocimetry and to studies of
rotational Brownian motion in a periodic lattice.Comment: 7 pages, 2 figures, to appear in JOSA
Multiple membrane cavity optomechanics
We investigate theoretically the extension of cavity optomechanics to
multiple membrane systems. We describe such a system in terms of the coupling
of the collective normal modes of the membrane array to the light fields. We
show these modes can be optically addressed individually and be cooled, trapped
and characterized, e.g. via quantum nondemolition measurements. Analogies
between this system and a linear chain of trapped ions or dipolar molecules
imply the possibility of related applications in the quantum regime.Comment: 4 pages, 2 figure
Cavity optomechanics with Si3N4 membranes at cryogenic temperatures
We describe a cryogenic cavity-optomechanical system that combines Si3N4
membranes with a mechanically-rigid Fabry-Perot cavity. The extremely high
quality-factor frequency products of the membranes allow us to cool a MHz
mechanical mode to a phonon occupation of less than 10, starting at a bath
temperature of 5 kelvin. We show that even at cold temperatures
thermally-occupied mechanical modes of the cavity elements can be a limitation,
and we discuss methods to reduce these effects sufficiently to achieve ground
state cooling. This promising new platform should have versatile uses for
hybrid devices and searches for radiation pressure shot noise.Comment: 19 pages, 5 figures, submitted to New Journal of Physic
Calibrated quantum thermometry in cavity optomechanics
Cavity optomechanics has achieved the major breakthrough of the preparation
and observation of macroscopic mechanical oscillators in peculiarly quantum
states. The development of reliable indicators of the oscillator properties in
these conditions is important also for applications to quantum technologies. We
compare two procedures to infer the oscillator occupation number, minimizing
the necessity of system calibrations. The former starts from homodyne spectra,
the latter is based on the measurement of the motional sidebands asymmetry in
heterodyne spectra. Moreover, we describe and discuss a method to control the
cavity detuning, that is a crucial parameter for the accuracy of the latter,
intrinsically superior procedure
A micropillar for cavity optomechanics
We present a new micromechanical resonator designed for cavity optomechanics.
We have used a micropillar geometry to obtain a high-frequency mechanical
resonance with a low effective mass and a very high quality factor. We have
coated a 60-m diameter low-loss dielectric mirror on top of the pillar and
are planning to use this micromirror as part of a high-finesse Fabry-Perot
cavity, to laser cool the resonator down to its quantum ground state and to
monitor its quantum position fluctuations by quantum-limited optical
interferometry
Cavity spin optodynamics
The dynamics of a large quantum spin coupled parametrically to an optical
resonator is treated in analogy with the motion of a cantilever in cavity
optomechanics. New spin optodynamic phenonmena are predicted, such as
cavity-spin bistability, optodynamic spin-precession frequency shifts, coherent
amplification and damping of spin, and the spin optodynamic squeezing of light.Comment: 4 pages, 3 figure
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