28,182 research outputs found
Continuity properties of a factor of Markov chains
Starting from a Markov chain with a finite alphabet, we consider the chain
obtained when all but one symbol are undistinguishable for the practitioner. We
study necessary and sufficient conditions for this chain to have continuous
transition probabilities with respect to the past
Geometric Phase for Fermionic Quasiparticles Scattering by Disgyration in Superfluids
We consider a Volovik's analog model for description of a topological defects
in a superfluid and we investigate the scattering of quasiparticles in this
background. The analog of the gravitational Aharonov-Bohm in this system is
found. An analysis of this problem employing loop variables is considered and
corroborates for the existence of the Aharonov-Bohm effect in this system. The
results presented here may be used to study the Aharonov-Bohm effect in
superconductors.Comment: 7 pages, to appear in Europhys. Let
Decoherence, pointer engineering and quantum state protection
We present a proposal for protecting states against decoherence, based on the
engineering of pointer states. We apply this procedure to the vibrational
motion of a trapped ion, and show how to protect qubits, squeezed states,
approximate phase eigenstates and superpositions of coherent states.Comment: 1 figur
Experimental evidence of laser power oscillations induced by the relative Fresnel (Goos-Haenchen) phase
The amplification of the relative Fresnel (Goos-Haenchen) phase by an
appropriate number of total internal reflections and the choice of favorable
incidence angles allow to observe full oscillations in the power of a DPSS
laser transmitted through sequential BK7 blocks. The experimental results
confirm the theoretical predictions. The optical apparatus used in this letter
can be seen as a new type of two-phase ellipsometric system where the phase of
the complex refractive index is replaced by the relative Fresnel
(Goos-Haenchen) phase.Comment: 7 pages, 3 figures, 1 tabl
Improved semiclassical density matrix: taming caustics
We present a simple method to deal with caustics in the semiclassical
approximation to the thermal density matrix of a particle moving on the line.
For simplicity, only its diagonal elements are considered. The only ingredient
we require is the knowledge of the extrema of the Euclidean action. The
procedure makes use of complex trajectories, and is applied to the quartic
double-well potential.Comment: 20 pages, 7 figures. Revised version, accepted for publication in
Phys. Rev.
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