3,429 research outputs found
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
Signatures of neutral quantum Hall modes in transport through low-density constrictions
Constrictions in fractional quantum Hall (FQH) systems not only facilitate
backscattering between counter-propagating edge modes, but also may reduce the
constriction filling fraction with respect to the bulk filling fraction
. If both and correspond to incompressible FQH states,
at least part of the constriction region is surrounded by composite edges,
whose low energy dynamics is characterized by a charge mode and one or several
neutral modes. In the incoherent regime, decay of neutral modes describes the
equilibration of composite FQH edges, while in the limit of coherent transport,
the presence of neutral modes gives rise to universal conductance fluctuations.
In addition, neutral modes renormalize the strength of scattering across the
constriction, and thus can determine the relative strength of forward and
backwards scattering.Comment: corrected description of the results of Ref. [10], Ref. [17] adde
The Physical Significance of Singularities in the Chern--Simons Fermi Liquid Description of a Partially Filled Landau Level
We analyze the linear response of a half filled Landau level to long
wavelength and low frequency driving forces, using Fermi liquid theory for
composite fermions. This response is determined by the composite fermions
quasi--particle effective mass, , and quasi--particle Landau interaction
function . Analyzing infra--red divergences of perturbation
theory, we get an exact expression for , and conjecture the form of the
. We then conclude that in the limit of infinite cyclotron
frequency, and small , the composite fermion excitation
spectrum is continuous for , with
an unknown number. For fractional quantum Hall states near a half
filled Landau level, we derive an exact expression for the energy gap.Comment: 4 pages, RevTeX. This paper, being short and non-technical, could
serve as a useful starting point for reading our manuscript cond-mat/9502032.
The present paper does, however, include results not published in the forme
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
Are Microwave Induced Zero Resistance States Necessarily Static?
We study the effect of inhomogeneities in Hall conductivity on the nature of
the Zero Resistance States seen in the microwave irradiated two-dimensional
electron systems in weak perpendicular magnetic fields, and we show that
time-dependent domain patterns may emerge in some situations. For an annular
Corbino geometry, with an equilibrium charge density that varies linearly with
radius, we find a time-periodic non-equilibrium solution, which might be
detected by a charge sensor, such as an SET. For a model on a torus, in
addition to static domain patterns seen at high and low values of the
equilibrium charge inhomogeneity, we find that, in the intermediate regime, a
variety of nonstationary states can also exist. We catalog the possibilities we
have seen in our simulations. Within a particular phenomenological model, we
show that linearizing the nonlinear charge continuity equation about a
particularly simple domain wall configuration and analyzing the eigenmodes
allows us to estimate the periods of the solutions to the full nonlinear
equation.Comment: Submitted to PR
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