62,730 research outputs found
Nonsymmetric transverse vibrations of truncated conical shells technical report no. 3
Resonant frequencies and associated mode shapes of truncated conical shells over wide range of geometrical and modal parameter
The entanglement beam splitter: a quantum-dot spin in a double-sided optical microcavity
We propose an entanglement beam splitter (EBS) using a quantum-dot spin in a
double-sided optical microcavity. In contrast to the conventional optical beam
splitter, the EBS can directly split a photon-spin product state into two
constituent entangled states via transmission and reflection with high fidelity
and high efficiency (up to 100 percent). This device is based on giant optical
circular birefringence induced by a single spin as a result of cavity quantum
electrodynamics and the spin selection rule of trion transition (Pauli
blocking). The EBS is robust and it is immune to the fine structure splitting
in a realistic quantum dot. This quantum device can be used for
deterministically creating photon-spin, photon-photon and spin-spin
entanglement as well as a single-shot quantum non-demolition measurement of a
single spin. Therefore, the EBS can find wide applications in quantum
information science and technology.Comment: 7 pages, 5 figure
Fluctuations of the vacuum energy density of quantum fields in curved spacetime via generalized zeta functions
For quantum fields on a curved spacetime with an Euclidean section, we derive
a general expression for the stress energy tensor two-point function in terms
of the effective action. The renormalized two-point function is given in terms
of the second variation of the Mellin transform of the trace of the heat kernel
for the quantum fields. For systems for which a spectral decomposition of the
wave opearator is possible, we give an exact expression for this two-point
function. Explicit examples of the variance to the mean ratio of the vacuum energy density of a
massless scalar field are computed for the spatial topologies of and , with results of , and
respectively. The large variance signifies the importance
of quantum fluctuations and has important implications for the validity of
semiclassical gravity theories at sub-Planckian scales. The method presented
here can facilitate the calculation of stress-energy fluctuations for quantum
fields useful for the analysis of fluctuation effects and critical phenomena in
problems ranging from atom optics and mesoscopic physics to early universe and
black hole physics.Comment: Uses revte
A study of joint discontinuity in vibrations of composite shells
Joint discontinuity in vibrations of composite /cone-cylinder/ shell
A rigorous derivation of second-approximation theory of elastic shells Technical report no. 5
Derivation of second approximation shell theor
Time-dependent Ginzburg-Landau equations for mixed d- and s-wave superconductors
A set of coupled time-dependent Ginzburg-Landau equations (TDGL) for
superconductors of mixed d- and s-wave symmetry are derived microscopically
from the Gor'kov equations by using the analytical continuation technique. The
scattering effects due to impurities with both nonmagnetic and magnetic
interactions are considered. We find that the d- and s-wave components of the
order parameter can have very different relaxation times in the presence of
nonmagnetic impurities. This result is contrary to a set of phenomenologically
proposed TDGL equations and thus may lead to new physics in the dynamics of
flux motion.Comment: 22 pages, 6 figures are available upon request, to appear in Phys.
Rev.
Decoherence in Quantum Gravity: Issues and Critiques
An increasing number of papers have appeared in recent years on decoherence
in quantum gravity at the Planck energy. We discuss the meaning of decoherence
in quantum gravity starting from the common notion that quantum gravity is a
theory for the microscopic structures of spacetime, and invoking some generic
features of quantum decoherence from the open systems viewpoint. We dwell on a
range of issues bearing on this process including the relation between
statistical and quantum, noise from effective field theory, the meaning of
stochasticity, the origin of non-unitarity and the nature of nonlocality in
this and related contexts. To expound these issues we critique on two
representative theories: One claims that decoherence in quantum gravity scale
leads to the violation of CPT symmetry at sub-Planckian energy which is used to
explain today's particle phenomenology. The other uses this process in place
with the Brownian motion model to prove that spacetime foam behaves like a
thermal bath.Comment: 25 pages, proceedings of DICE06 (Piombino
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