63 research outputs found
Two-dimensional phononic-photonic bandgap optomechanical crystal cavity
We present the fabrication and characterization of an artificial crystal
structure formed from a thin-film of silicon which has a full phononic bandgap
for microwave X-band phonons and a two-dimensional pseudo-bandgap for
near-infrared photons. An engineered defect in the crystal structure is used to
localize optical and mechanical resonances in the bandgap of the planar
crystal. Two-tone optical spectroscopy is used to characterize the cavity
system, showing a large vacuum coupling rate of 220kHz between the fundamental
optical cavity resonance at 195THz and a co-localized mechanical resonance at
9.3GHz.Comment: 4 pages, 4 figure
Observation of non-Markovian micro-mechanical Brownian motion
All physical systems are to some extent open and interacting with their
environment. This insight, basic as it may seem, gives rise to the necessity of
protecting quantum systems from decoherence in quantum technologies and is at
the heart of the emergence of classical properties in quantum physics. The
precise decoherence mechanisms, however, are often unknown for a given system.
In this work, we make use of an opto-mechanical resonator to obtain key
information about spectral densities of its condensed-matter heat bath. In
sharp contrast to what is commonly assumed in high-temperature quantum Brownian
motion describing the dynamics of the mechanical degree of freedom, based on a
statistical analysis of the emitted light, it is shown that this spectral
density is highly non-Ohmic, reflected by non-Markovian dynamics, which we
quantify. We conclude by elaborating on further applications of opto-mechanical
systems in open system identification.Comment: 5+6 pages, 3 figures. Replaced by final versio
Mechanical overtone frequency combs
Mechanical frequency combs are poised to bring the applications and utility
of optical frequency combs into the mechanical domain. So far, their use has
been limited by strict conditions on drive frequencies and power, small
bandwidths and complicated modes of operation. We demonstrate a novel,
straightforward mechanism to create a frequency comb consisting of mechanical
overtones (integer multiples) of a single eigenfrequency, by monolithically
integrating a suspended dielectric membrane with a counter-propagating optical
trap generated via its own substrate. The periodic optical field modulates the
dielectrophoretic force on the membrane at integer multiples of the membrane's
frequency of motion, thus efficiently creating overtones of that frequency and
forming a frequency comb. Using the same periodic optical field, we
simultaneously demonstrate a strong, parametric thermal driving mechanism that
requires no additional power or frequency reference. The combination of these
effects results in a versatile, easy-to-use mechanical frequency comb platform
that requires no precise alignment, no additional feedback or control
electronics, and only uses a single, mW continuous wave laser beam. This
highlights the mechanical frequency comb as a low-power, on-chip alternative to
optical frequency combs for sensing, timing and metrology applications
On optical forces in spherical whispering gallery mode resonators
In this paper we discuss the force exerted by the field of an optical cavity
on a polarizable dipole. We show that the modification of the cavity modes due
to interaction with the dipole significantly alters the properties of the
force. In particular, all components of the force are found to be
non-conservative, and cannot, therefore, be derived from a potential energy. We
also suggest a simple generalization of the standard formulas for the optical
force on the dipole, which reproduces the results of calculations based on the
Maxwell stress tensor.Comment: To pe published in Optics Express Focus Issue: "Collective phenomena
in photonic, plasmonic and hybrid structures
Quantum mechanical effect of path-polarization contextuality for a single photon
Using measurements pertaining to a suitable Mach-Zehnder(MZ) type setup, a
curious quantum mechanical effect of contextuality between the path and the
polarization degrees of freedom of a polarized photon is demonstrated, without
using any notion of realism or hidden variables - an effect that holds good for
the product as well as the entangled states. This form of experimental
context-dependence is manifested in a way such that at \emph{either} of the two
exit channels of the MZ setup used, the empirically verifiable
\emph{subensemble} statistical properties obtained by an arbitrary polarization
measurement depend upon the choice of a commuting(comeasurable) path
observable, while this effect disappears for the \emph{whole ensemble} of
photons emerging from the two exit channels of the MZ setup.Comment: To be published in IJT
Experimental test of nonclassicality for a single particle
In a recent paper [R. Alicki and N. Van Ryn, J. Phys. A: Math. Theor., 41,
062001 (2008)] a test of nonclassicality for a single qubit was proposed. Here,
we discuss the class of local realistic theories to which this test applies and
present an experimental realization
Nanomechanical motion measured with precision beyond the standard quantum limit
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. For example, if the imprecision of a measurement of an oscillator's
position is pushed below the standard quantum limit (SQL), quantum mechanics
demands that the motion of the oscillator be perturbed by an amount larger than
the SQL. Minimizing this quantum backaction noise and nonfundamental, or
technical, noise requires an information efficient measurement. Here we
integrate a microwave cavity optomechanical system and a nearly noiseless
amplifier into an interferometer to achieve an imprecision below the SQL. As
the microwave 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/rt(Hz). In addition, the demonstrated
efficient measurement is a critical step towards entangling mechanical
oscillators with other quantum systems.Comment: 5 pages, 4 figure
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