3,625 research outputs found
A scheme for symmetrization verification
We propose a scheme for symmetrization verification in two-particle systems,
based on one-particle detection and state determination. In contrast to
previous proposals, it does not follow a Hong-Ou-Mandel-type approach.
Moreover, the technique can be used to generate superposition states of single
particles
The Bragg regime of the two-particle Kapitza-Dirac effect
We analyze the Bragg regime of the two-particle Kapitza-Dirac arrangement,
completing the basic theory of this effect. We provide a detailed evaluation of
the detection probabilities for multi-mode states, showing that a complete
description must include the interaction time in addition to the usual
dimensionless parameter w. The arrangement can be used as a massive
two-particle beam splitter. In this respect, we present a comparison with
Hong-Ou-Mandel-type experiments in quantum optics. The analysis reveals the
presence of dips for massive bosons and a differentiated behavior of
distinguishable and identical particles in an unexplored scenario. We suggest
that the arrangement can provide the basis for symmetrization verification
schemes
White noise flashing Brownian pump
A Brownian pump of particles powered by a stochastic flashing ratchet
mechanism is studied. The pumping device is embedded in a finite region and
bounded by particle reservoirs. In the steady state, we exactly calculate the
spatial density profile, the concentration ratio between both reservoirs and
the particle flux. A simple numerical scheme is presented allowing for the
consistent evaluation of all such observable quantities
Coexistence of Quantum Theory and Special Relativity in signaling scenarios
The coexistence between Quantum Mechanics and Special Relativity is usually
formulated in terms of the no-signaling condition. Several authors have even
suggested that this condition should be included between the basic postulates
of Quantum Theory. However, there are several scenarios where signaling is, in
principle, possible: based on previous results and the analysis of the relation
between unitarity and signaling we present an example of a two-particle
interferometric arrangement for which the dynamics is, in principle, compatible
with superluminal transmission of information. This type of non-locality is not
in the line of Bell's theorem, but closer in spirit to the one-particle
acausality studied by Hegerfeldt and others. We analyze in this paper the
meaning of this non-locality and how to preserve the coexistence of the two
fundamental theories in this signaling scenario.Comment: See also the comment by G C Hegerfeldt in the online version of the
journal, including more reference
Heat Fluctuations in Brownian Transducers
Heat fluctuation probability distribution function in Brownian transducers
operating between two heat reservoirs is studied. We find, both analytically
and numerically, that the recently proposed Fluctuation Theorem for Heat
Exchange [C. Jarzynski and D. K. Wojcik, Phys. Rev. Lett. 92, 230602 (2004)]
has to be modified when the coupling mechanism between both baths is
considered. We also extend such relation when external work is present. Our
work fixes the domain of applicability of the theorem in more realistic
operating systems.Comment: Comments are welcom
The effect of vacancy-induced magnetism on electronic transport in armchair carbon nanotubes
The influence of local magnetic moment formation around three kinds of
vacancies on the electron conduction through metallic single-wall carbon
nanotubes is studied by use of the Landauer formalism within the coherent
regime. The method is based on the single-band tight-binding Hamiltonian, a
surface Green's function calculation, and the mean-field Hubbard model. The
numerical results show that the electronic transport is spin-polarized due to
the localized magnetic moments and it is strongly dependent on the geometry of
the vacancies. For all kinds of vacancies, by including the effects of local
magnetic moments, the electron scattering increases with respect to the
nonmagnetic vacancies case and hence, the current-voltage characteristic of the
system changes. In addition, a high value for the electron-spin polarization
can be obtained by applying a suitable gate voltage.Comment: 6 pages, 6 figure
Synthetizing hydrodynamic turbulence from noise: formalism and applications to plankton dynamics
We present an analytical scheme, easily implemented numerically, to generate synthetic Gaussian 2D turbulent flows by using linear stochastic partial differential equations, where the noise term acts as a random force of well-prescribed statistics. This methodology leads to a divergence-free, isotropic, stationary and homogeneous velocity field, whose characteristic parameters are well reproduced, in particular the kinematic viscosity and energy spectrum. This practical approach to tailor a turbulent flow is justified by its versatility when analizing different physical processes occurring in advectely mixed systems. Here, we focuss on an application to study the dynamics of Planktonic populations in the ocean
Dynamics and Scaling of Noise-Induced Domain Growth
The domain growth processes originating from noise-induced nonequilibrium
phase transitions are analyzed, both for non-conserved and conserved dynamics.
The existence of a dynamical scaling regime is established in the two cases,
and the corresponding growth laws are determined. The resulting universal
dynamical scaling scenarios are those of Allen-Cahn and Lifshitz-Slyozov,
respectively. Additionally, the effect of noise sources on the behaviour of the
pair correlation function at short distances is studied.Comment: 11 pages (including 13 figures) LaTeX file. Accepted in EPJ
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