11,791 research outputs found
Chip-scale cavity optomechanics in lithium niobate
We develop a chip-scale cavity optomechanical system in single-crystal
lithium niobate that exhibits high optical quality factors and a large
frequency-quality product as high as Hz at room temperature
and atmosphere. The excellent optical and mechanical properties together with
the strong optomechanical coupling allow us to efficiently excite the coherent
regenerative optomechanical oscillation operating at 375.8 MHz with a threshold
power of 174 in the air. The demonstrated lithium niobate
optomechanical device enables great potential for achieving
electro-optic-mechanical hybrid systems for broad applications in sensing,
metrology, and quantum physics
Quantum correlations from dynamically modulated optical nonlinear interactions
We investigate optical nonlinear interactions in a dynamic environment by
studying generation of photons in spontaneous parametric down conversion inside
a nonlinear cavity where the optical path length is periodically modulated in
time. We show that the temporal dynamics of the cavity modify the nonlinear
interaction and the generated continuous variable time-frequency entangled
bi-photon state evolves into a tunable discrete higher dimensional state in the
non-adiabatic modulation regime where the modulation time scales are much
faster than the photon lifetime. In this regime, the system mimics effects of a
quantum random walk in a photonic lattice with many associated effects
including localized and delocalized wavefunctions of the generated photons. We
also propose generation of time-frequency hyper-entangled states in the
adiabatic limit. Our analysis shows that the proposed system is promising for
applications in quantum simulation and information processing in the
time-frequency domain.Comment: 10 pages, 6 figures (including appendix
The direction of the -vector in a nematic triplet superconductor
We investigate the states of triplet pairing in a candidate nematic
superconductor versus typical material parameters, using the mean field theory
for two- and three-dimensional tight-binding models with local triplet pairing
in the representation. In the two-dimensional model, the system favors
the fully gapped chiral state for weaker warping or lower filling level, while
a nodal and nematic state is favorable for stronger warping or
higher filling, with the -vector aligned along the principle axis. In the
presence of lattice distortion, relative elongation along one of the principle
axes, , tends to rotate the nematic -vector orthogonal to , resulting in the nematic state at sufficient elongation.
Three-dimensionality is seen to suppress the chiral state in favor of the
nematic ones. Our results may explain the variety in the probed direction of
the -vector in existing experiments.Comment: 5 pages, 4 color figure
The Deviation of the Vacuum Refractive Index Induced by a Static Gravitational Field
We analyzed the influence of static gravitational field on the vacuum and
proposed the concept of inhomogeneous vacuum. According to the observational
result of the light deflection in solar gravitational field as well as the
corresponding Fermat's principle in the general relativity, we derived an
analytical expression of the refractive index of vacuum in a static
gravitational field. We found that the deviation of the vacuum refractive index
is composed of two parts: one is caused by the time dilation effect, the other
is caused by the length contraction effect. As an application, we simulated the
effect of the gravitational lensing through computer programming and found that
the missing central imaging could be interpreted in a reasonable way.Comment: 5 pages, 6 figure
Self-Frequency Shift of Cavity Soliton in Kerr Frequency Comb
We show that the ultrashort cavity soliton in octave-spanning Kerr frequency
comb generation exhibits striking self-adaptiveness and robustness to external
perturbations, resulting in a novel frequency shifting/cancellation mechanism
and gigantic dispersive wave generation in response to the strong frequency
dependence of Kerr nonlinearity, Raman scattering, chromatic dispersion, and
cavity Q. These observations open up a great avenue towards versatile
manipulation of nonlinear soliton dynamics, flexible spectrum engineering of
mode-locked Kerr frequency combs, and highly efficient frequency translation of
optical waves
Partial classification of cuspidal simple modules for Virasoro-like algebra
Let be the Lie algebra of Hamiltonian vector fields on the
torus, which is also known as the Virasoro-like algebra, a special kind of the
so-called Block type Lie algebra. And let be the Laurent
polynomial algebra in two variables. In this paper, by following S.E. Rao's
strategy of "backward induction", we prove that any quasi-finite simple
-module has to come from Larsson-Shen's
construction.Comment: 14 page
Multicolor Bound Soliton Molecule
We show a new class of bound soliton molecule that exists in a parametrically
driven nonlinear optical cavity with appropriate dispersion characteristics.
The composed solitons exhibit distinctive colors but coincide in time and share
a common phase, bound together via strong inter-soliton four-wave mixing and
Cherenkov radiation. The multicolor bound soliton molecule shows intriguing
spectral locking characteristics and remarkable capability of spectrum
management to tailor soliton frequencies, which may open up a great avenue
towards versatile generation and manipulation of multi-octave spanning
phase-locked Kerr frequency combs, with great potential for applications in
frequency metrology, optical frequency synthesis, and spectroscopy.Comment: 5 pages, 6 figure
High-frequency and high-quality silicon carbide optomechanical microresonators
Silicon carbide (SiC) exhibits excellent material properties attractive for
broad applications. We demonstrate the first SiC optomechanical microresonators
that integrate high mechanical frequency, high mechanical quality, and high
optical quality into a single device. The radial-breathing mechanical mode has
a mechanical frequency up to 1.69 GHz with a mechanical Q around 5500 in
atmosphere, which corresponds to a mechanical f-Q product as high as 9.47x10^12
Hz. The strong optomechanical coupling allows us to efficiently excite and
probe the coherent mechanical oscillation by optical waves. The demonstrated
devices, in combination with the superior thermal property, chemical inertness,
and defect characteristics of SiC, show great potential for applications in
metrology, sensing, and quantum photonics, particularly in harsh environments
that are challenging for other device platforms.Comment: 18 pages, 5 figure
Novel polymer nanocomposite composed of organic nanoparticles via self-assembly
We report a novel class of polymer nanocomposite composed of organic
nanoparticles dispersed in polymer matrix, with the particle sizes of 30-120 nm
in radius. The organic nanoparticles were formed by the self-assembly of
protonated poly(4-vinyl-pyridine)-r-poly(acrylonitrile) and amphiphilic metanil
yellow dye molecules through electrostatic interactions in aqueous solution. A
strongly broadened Raman shift band was probed, suggesting the presence of
enhanced optoelectronic property from the polymer nanocomposite. Here, using
random-copolymer polyelectrolytes and mesogenic amphiphiles as the designed
building blocks for self-assembly, a new approach is acutally provided to
fabricate organic nanoparticles.Comment: 12 pages, 5 figures
Further results on complete permutation monomials over finite fields
In this paper, we construct some new classes of complete permutation
monomials with exponent using AGW criterion (a special
case). This proves two recent conjectures in [Wuetal2] and extends some of
these recent results to more general 's
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