511 research outputs found
One-mirror Fabry-Perot and one-slit Young interferometry
We describe a new and distinctive interferometry in which a probe particle
scatters off a superposition of locations of a single free target particle. In
one dimension, probe particles incident on superposed locations of a single
"mirror" can interfere as if in a Fabry-Perot interferometer; in two
dimensions, probe particles scattering off superposed locations of a single
"slit" can interfere as if in a two-slit Young interferometer. The condition
for interference is loss of orthogonality of the target states and reduces, in
simple examples, to transfer of orthogonality from target to probe states. We
analyze experimental parameters and conditions necessary for interference to be
observed.Comment: 5 pages, 2 figures, RevTeX, submitted to PR
Hydrodynamics in 1+1 dimensions with gravitational anomalies
The constraints imposed on hydrodynamics by the structure of gauge and
gravitational anomalies are studied in two dimensions. By explicit integration
of the consistent gravitational anomaly, we derive the equilibrium partition
function at second derivative order. This partition function is then used to
compute the parity-violating part of the covariant energy-momentum tensor and
the transport coefficients.Comment: 9 pages, JHEP format.v2; added comments and references, matching
published versio
Constraints on Superfluid Hydrodynamics from Equilibrium Partition Functions
Following up on recent work in the context of ordinary fluids, we study the
equilibrium partition function of a 3+1 dimensional superfluid on an arbitrary
stationary background spacetime, and with arbitrary stationary background gauge
fields, in the long wavelength expansion. We argue that this partition function
is generated by a 3 dimensional Euclidean effective action for the massless
Goldstone field. We parameterize the general form of this action at first order
in the derivative expansion. We demonstrate that the constitutive relations of
relativistic superfluid hydrodynamics are significantly constrained by the
requirement of consistency with such an effective action. At first order in the
derivative expansion we demonstrate that the resultant constraints on
constitutive relations coincide precisely with the equalities between
hydrodynamical transport coefficients recently derived from the second law of
thermodynamics.Comment: 46 page
Coherence Resonance and Noise-Induced Synchronization in Globally Coupled Hodgkin-Huxley Neurons
The coherence resonance (CR) of globally coupled Hodgkin-Huxley neurons is
studied. When the neurons are set in the subthreshold regime near the firing
threshold, the additive noise induces limit cycles. The coherence of the system
is optimized by the noise. A bell-shaped curve is found for the peak height of
power spectra of the spike train, being significantly different from a
monotonic behavior for the single neuron. The coupling of the network can
enhance CR in two different ways. In particular, when the coupling is strong
enough, the synchronization of the system is induced and optimized by the
noise. This synchronization leads to a high and wide plateau in the local
measure of coherence curve. The local-noise-induced limit cycle can evolve to a
refined spatiotemporal order through the dynamical optimization among the
autonomous oscillation of an individual neuron, the coupling of the network,
and the local noise.Comment: five pages, five figure
Collective dynamics of two-mode stochastic oscillators
We study a system of two-mode stochastic oscillators coupled through their
collective output. As a function of a relevant parameter four qualitatively
distinct regimes of collective behavior are observed. In an extended region of
the parameter space the periodicity of the collective output is enhanced by the
considered coupling. This system can be used as a new model to describe
synchronization-like phenomena in systems of units with two or more oscillation
modes. The model can also explain how periodic dynamics can be generated by
coupling largely stochastic units. Similar systems could be responsible for the
emergence of rhythmic behavior in complex biological or sociological systems.Comment: 4 pages, RevTex, 5 figure
(Non)-Renormalization of the Chiral Vortical Effect Coefficient
We show using diagramtic arguments that in some (but not all) cases, the
temperature dependent part of the chiral vortical effect coefficient is
independent of the coupling constant. An interpretation of this result in terms
of quantization in the effective 3 dimensional Chern-Simons theory is also
given. In the language of 3D dimensionally reduced theory, the value of the
chiral vortical coefficient is related to the formula . We also show that in the presence of dynamical gauge fields, the CVE
coefficient is not protected from renormalization, even in the large limit.Comment: 11 pages, 3 figures. Version 2 corrects an error and calculates
leading radiative correctio
Memory functions and Correlations in Additive Binary Markov Chains
A theory of additive Markov chains with long-range memory, proposed earlier
in Phys. Rev. E 68, 06117 (2003), is developed and used to describe statistical
properties of long-range correlated systems. The convenient characteristics of
such systems, a memory function, and its relation to the correlation properties
of the systems are examined. Various methods for finding the memory function
via the correlation function are proposed. The inverse problem (calculation of
the correlation function by means of the prescribed memory function) is also
solved. This is demonstrated for the analytically solvable model of the system
with a step-wise memory function.Comment: 11 pages, 5 figure
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