1,250 research outputs found
Giant Gravitons with NSNS B field
We study the motion of a D(8-p)-brane probe in the background created by a
stack of non-threshold (D(p-2), Dp) bound states for . The brane
probe and the branes of the background have two common directions. We show that
for a particular value of the worldvolume gauge field there exist
configurations of the probe brane which behave as massless particles and can be
interpreted as gravitons blown up into a fuzzy sphere and a noncommutative
plane. We check this behaviour by studying the motion and energy of the brane
and by determining how supersymmetry is broken by the probe as it moves under
the action of the background.Comment: 24 pages, LaTe
Flux Stabilization of D-branes in a non-threshold bound state background
We study some configurations of brane probes which are partially wrapped on
spheres transverse to a stack of non-threshold bound states. The latter are
represented by the corresponding supergravity background. Two cases are
studied: D(10-p)-branes in the background of (D(p-2), Dp) bound states and
D(8-p)-branes in the (NS5, Dp) geometry. By using suitable flux quantization
rules of the worldvolume gauge field, we determine the stable configurations of
the probe. The analysis of the energy and supersymmetry of these configurations
reveals that they can be interpreted as bound states of lower dimensional
objects polarized into a D-brane.Comment: 11 pages, LaTe
Primary-Filling e/3 Quasiparticle Interferometer
We report experimental realization of a quasiparticle interferometer where
the entire system is in 1/3 primary fractional quantum Hall state. The
interferometer consists of chiral edge channels coupled by quantum-coherent
tunneling in two constrictions, thus enclosing an Aharonov-Bohm area. We
observe magnetic flux and charge periods h/e and e/3, equivalent to creation of
one quasielectron in the island. Quantum theory predicts a 3h/e flux period for
charge e/3, integer statistics particles. Accordingly, the observed periods
demonstrate the anyonic statistics of Laughlin quasiparticles
Electron interferometry in quantum Hall regime: Aharonov-Bohm effect of interacting electrons
An apparent h/fe Aharonov-Bohm flux period, where f is an integer, has been
reported in coherent quantum Hall devices. Such sub-period is not expected for
non-interacting electrons and thus is thought to result from interelectron
Coulomb interaction. Here we report experiments in a Fabry-Perot interferometer
comprised of two wide constrictions enclosing an electron island. By carefully
tuning the constriction front gates, we find a regime where interference
oscillations with period h/2e persist throughout the transition between the
integer quantum Hall plateaus 2 and 3, including half-filling. In a large
quantum Hall sample, a transition between integer plateaus occurs near
half-filling, where the bulk of the sample becomes delocalized and thus
dissipative bulk current flows between the counterpropagating edges
("backscattering"). In a quantum Hall constriction, where conductance is due to
electron tunneling, a transition between forward- and back-scattering is
expected near the half-filling. In our experiment, neither period nor amplitude
of the oscillations show a discontinuity at half-filling, indicating that only
one interference path exists throughout the transition. We also present
experiments and an analysis of the front-gate dependence of the phase of the
oscillations. The results point to a single physical mechanism of the observed
conductance oscillations: Aharonov-Bohm interference of interacting electrons
in quantum Hall regime.Comment: 10 pages, 4 Fig
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