1,413 research outputs found
Non-Abelian Braiding of Lattice Bosons
We report on a numerical experiment in which we use time-dependent potentials
to braid non-abelian quasiparticles. We consider lattice bosons in a uniform
magnetic field within the fractional quantum Hall regime, where , the
ratio of particles to flux quanta, is near 1/2, 1 or 3/2. We introduce
time-dependent potentials which move quasiparticle excitations around one
another, explicitly simulating a braiding operation which could implement part
of a gate in a quantum computation. We find that different braids do not
commute for near and , with Berry matrices respectively
consistent with Ising and Fibonacci anyons. Near , the braids commute.Comment: 5 pages, 1 figur
A new Proposal for a Quasielectron Trial Wavefunction for the FQHE on a Disk
In this letter, we propose a new quasielectron trial wavefunction for
interacting electrons in two dimensions moving in a strong magnetic field in a
disk geometry. Requiring that the trial wavefunction exhibits the correct
filling factor of a quasielectron wavefunction, we obtain angular
momentum eigenfunctions. The expectation values of the energy are calculated
and compared with the data of an exact numerical diagonalization.Comment: 8 page
The ras-related mouse ypt1 protein can functionally replace the YPT1 gene product in yeast.
The protein-coding region of the essential Saccharomyces cerevisiae YPT1 gene coding for a ras-related, guanine-nucleotide-binding protein was exchanged in chromosome VI by the protein-coding segment of either the mouse ypt1 gene or the v-Ki-ras gene, and different chimeric YPT1-v-Ki-ras genes. The mouse ypt1 protein with 71% of identical residues compared with the yeast Ypt1 protein could functionally fully replace its yeast homologue as long as the mouse gene was overexpressed under transcriptional control of the inducible GAL10 promoter. In contrast, neither the viral Ki-ras nor the hybrid proteins were able to substitute for the loss of YPT1 gene function. This study suggests that different parts of the yeast Ypt1 protein are required for the interaction with cellular targets and that these essential parts are conserved in the mammalian ypt1 protein
Magnetic oscillations in planar systems with the Dirac-like spectrum of quasiparticle excitations II: transport properties
The quantum magnetic oscillations of electrical (Shubnikov de Haas effect)
and thermal conductivities are studied for graphene which represents a
distinctive example of planar systems with a linear, Dirac-like spectrum of
quasiparticle excitations. We show that if a utmost care was taken to separate
electron and phonon contributions in the thermal conductivity, the oscillations
of electron thermal conductivity, and the Lorenz number,
would be observable in the low field (less than a few Teslas) regime.Comment: 11 pages, RevTeX4, 6 EPS figures; 2 references, 1 figure and one more
section are added; final version published in PR
Optical Hall Effect in the Integer Quantum Hall Regime
Optical Hall conductivity is measured from the Faraday
rotation for a GaAs/AlGaAs heterojunction quantum Hall system in the terahertz
frequency regime. The Faraday rotation angle ( fine structure constant
mrad) is found to significantly deviate from the Drude-like behavior to
exhibit a plateau-like structure around the Landau-level filling . The
result, which fits with the behavior expected from the carrier localization
effect in the ac regime, indicates that the plateau structure, although not
quantized, still exists in the terahertz regime.Comment: 4 pages, 4 figure
Hyperfine interaction induced critical exponents in the quantum Hall effect
We study localization-delocalization transition in quantum Hall systems with
a random field of nuclear spins acting on two-dimensional (2d) electron spins
via hyperfine contact (Fermi) interaction. We use Chalker-Coddington network
model, which corresponds to the projection onto the lowest Landau level. The
inhomogeneous nuclear polarization acts on the electrons as an additional
confining potential, and, therefore, introduces additional parameter (the
probability to find a polarized nucleus in the vicinity of a saddle point of
random potential) responsible for the change from quantum to classical
behavior. In this manner we obtain two critical exponents corresponding to
quantum and classical percolation. We also study how the 2d extended state
develops into the one-dimensional (1d) critical state.Comment: 9 pages, 3 figure
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