30,878 research outputs found
Magnetic field-tuned Aharonov-Bohm oscillations and evidence for non-Abelian anyons at v=5/2
We show that the resistance of the v=5/2 quantum Hall state, confined to an
interferometer, oscillates with magnetic field consistent with an Ising-type
non-Abelian state. In three quantum Hall interferometers of different sizes,
resistance oscillations at v=7/3 and integer filling factors have the magnetic
field period expected if the number of quasiparticles contained within the
interferometer changes so as to keep the area and the total charge within the
interferometer constant. Under these conditions, an Abelian state such as the
(3,3,1) state would show oscillations with the same period as at an integer
quantum Hall state. However, in an Ising-type non-Abelian state there would be
a rapid oscillation associated with the "even-odd effect" and a slower one
associated with the accumulated Abelian phase due to both the Aharonov-Bohm
effect and the Abelian part of the quasiparticle braiding statistics. Our
measurements at v=5/2 are consistent with the latter.Comment: 10 pages, 8 figures, includes Supplemental Material
Coulomb Oscillations in Antidots in the Integer and Fractional Quantum Hall Regimes
We report measurements of resistance oscillations in micron-scale antidots in
both the integer and fractional quantum Hall regimes. In the integer regime, we
conclude that oscillations are of the Coulomb type from the scaling of magnetic
field period with the number of edges bound to the antidot. Based on both
gate-voltage and field periods, we find at filling factor {\nu} = 2 a tunneling
charge of e and two charged edges. Generalizing this picture to the fractional
regime, we find (again, based on field and gate-voltage periods) at {\nu} = 2/3
a tunneling charge of (2/3)e and a single charged edge.Comment: related papers at http://marcuslab.harvard.ed
Zero-Bias Anomalies in Narrow Tunnel Junctions in the Quantum Hall Regime
We report on the study of cleaved-edge-overgrown line junctions with a
serendipitously created narrow opening in an otherwise thin, precise line
barrier. Two sets of zero-bias anomalies are observed with an enhanced
conductance for filling factors and a strongly suppressed conductance
for . A transition between the two behaviors is found near . The zero-bias anomaly (ZBA) line shapes find explanation in
Luttinger liquid models of tunneling between quantum Hall edge states. The ZBA
for occurs from strong backscattering induced by suppression of
quasiparticle tunneling between the edge channels for the Landau
levels. The ZBA for arises from weak tunneling of quasiparticles
between the edge channels.Comment: version with edits for clarit
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