4,565 research outputs found
Understanding the dynamics of fractional edge states with composite fermions
Fractional edge states can be viewed as integer edge states of composite
fermions. We exploit this to discuss the conductance of the fractional
quantized Hall states and the velocity of edge magnetoplasmons.Comment: 3 pages, revte
Interference, Coulomb blockade, and the identification of non-abelian quantum Hall states
We examine the relation between different electronic transport phenomena in a
Fabry-Perot interferometer in the fractional quantum Hall regime. In
particular, we study the way these phenomena reflect the statistics of quantum
Hall quasi-particles. For two series of states we examine, one abelian and one
non-abelian, we show that the information that may be obtained from
measurements of the lowest order interference pattern in an open Fabry-Perot
interferometer is identical to the one that may be obtained from the
temperature dependence of Coulomb blockade peaks in a closed interferometer. We
argue that despite the similarity between the experimental signatures of the
two series of states, interference and Coulomb blockade measurements are likely
to be able to distinguish between abelian and non-abelian states, due to the
sensitivity of the abelian states to local perturbations, to which the
non-abelian states are insensitive.Comment: 10 pages. Published versio
Screening of electrostatic potential in a composite fermion system
Screening of the electric field of a test charge by monolayer and
double-layer composite fermion systems is considered. It is shown that the
electric field of the test charge is partly screened at distances much large
then the magnetic length. The value of screening as a function of the distance
depends considerably on the filling factor. The effect of variation of the
value of screening in the double-layer system upon a transition to a state
described by the Halperin wave function is determined.Comment: 5 pages, 2 eps figures include
Exact Groundstates of Rotating Bose Gases close to a Feshbach Resonance
We study the groundstates of rotating Bose gases when interactions are
affected by a nearby Feshbach resonance. We show that exact groundstates at
high angular momentum can be found analytically for a general and realistic
model for the resonant interactions. We identify parameter regimes where the
exact groundstates are exotic fractional quantum Hall states, the excitations
of which obey non-abelian exchange statistics.Comment: 4 page
Interaction of quantum Hall systems with waveguide elastic modes
An interaction of non-uniform plane elastic modes of the waveguide type with
monolayer and double-layer quantum Hall systems is considered. It is shown,
that unlike the case of the surface acoustic wave propagation, the restriction
on maximal values of the wave vectors for which the velocity shift can be
observed experimentally does not take place for the waveguide modes. In case of
study of incompressible fractional quantum Hall states the effect can be used
for measuring a dependence of the effective magnetic length on the filling
factor and for observing phase transitions in double-layer system under the
interlayer distance variationComment: 6 pages, 3 eps figures included, Fig.1 and Fig.3 correcte
Consequences of a possible adiabatic transition between \nu=1/3 and \nu=1 quantum Hall states in a narrow wire
We consider the possibility of creating an adiabatic transition through a
narrow neck, or point contact, between two different quantized Hall states that
have the same number of edge modes, such as \nu=1 and \nu=1/3. We apply both
the composite fermion and the Luttinger liquid formalism to analyze the
transition. We suggest that using such adiabatic junctions one could build a DC
step-up transformer, where the output voltage is higher than the input.
Difficulties standing in the way of an experimental implementation of the
adiabatic junction are addressed.Comment: 4 pages RevTex, includes 2 eps figures, Submitted to Phys. Rev. Let
Transport equations for a two-dimensional electron gas with spin-orbit interaction
The transport equations for a two-dimensional electron gas with spin-orbit
interaction are presented. The distribution function is a 2x2-matrix in the
spin space. Particle and energy conservation laws determine the expressions for
the electric current and the energy flow. The derived transport equations are
applied to the spin-splitting of a wave packed and to the calculation of the
structure factor and the dynamic conductivity.Comment: 6 pages, 1 figure, revised versio
s-wave Cooper pair insulators and theory of correlated superconductors
The pseudogap state of cuprate high-temperature superconductors has been
often viewed as either a yet unknown competing order or a precursor state to
superconductivity. While awaiting the resolution of the pseudogap problem in
cuprates, we demonstrate that local pairing fluctuations, vortex liquid
dynamics and other precursor phenomena can emerge quite generally whenever
fermionic excitations remain gapped across the superconducting transition,
regardless of the gap origin. Our choice of a tractable model is a lattice band
insulator with short-range attractive interactions between fermions in the
s-wave channel. An effective crossover between Bardeen-Cooper-Schrieffer (BCS)
and Bose-Einstein condensate (BEC) regimes can be identified in any band
insulator above two dimensions, while in two dimensions only the BEC regime
exists. The superconducting transition is "unconventional" (non-pair-breaking)
in the BEC regime, identified by either the bosonic mean-field or XY
universality class. The insulator adjacent to the superconductor in the BEC
regime is a bosonic Mott insulator of Cooper pairs, which may be susceptible to
charge density wave ordering. We construct a function of the many-body
excitation spectrum whose non-analytic changes define a sharp distinction
between band and Mott insulators. The corresponding "second order transition"
can be observed out of equilibrium by driving a Cooper pair laser in the Mott
insulator. We explicitly show that the gap for charged bosonic excitations lies
below the threshold for Cooper pair breakup in any BEC regime, despite quantum
fluctuations. Our discussion ends with a view of possible consequences for
cuprates, where antinodal pair dynamics has certain features in common with our
simple s-wave picture.Comment: 18 pages, 4 figures, published versio
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