14,412 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
On the giant magnon and spike solutions for strings on AdS S
We study solutions for the rotating strings on the sphere with a background
NS-NS field and on the Anti-de-Sitter spacetime. We show the existence of
magnon and single spike solutions on RS in the presence of constant
magnetic field as two limiting cases. We also study the solution for strings on
AdS S with Melvin deformation. The dispersion relations among
various conserved charges are shown to receive finite corrections due to the
deformation parameter. We further study the rotating string on AdS
S geometry with two conserved angular momenta on S and one spin along
the AdS. We show that there exists two kinds of solutions: a circular
string solution and a helical string. We find out the dispersion relation among
various charges and give physical interpretation of these solutions.Comment: 18 pages, 1 figure, typos fixed, minor changes, to appear in JHE
Evolution of Primordial Black Holes in Loop Quantum Gravity
In this work, we study the evolution of Primordial Black Holes within the
context of Loop Quantum Gravity. First we calculate the scale factor and energy
density of the universe for different cosmic era and then taking these as
inputs we study evolution of primordial black holes. From our estimation it is
found that accretion of radiation does not affect evolution of primordial black
holes in loop quantum gravity even though a larger number of primordial black
holes may form in early universe in comparison with Einstein's or scalar-tensor
theories.Comment: 8 pages, 1 figur
Correlation between stick-slip frictional sliding and charge transfer
A decade ago, Budakian and Putterman (Phys. Rev. Lett., {\bf 85}, 1000
(2000)) ascribed friction to the formation of bonds arising from contact
charging when a gold tip of a surface force apparatus was dragged on
polymethylmethacrylate surface. We propose a stick-slip model that captures the
observed correlation between stick-slip events and charge transfer, and the
lack of dependence of the scale factor connecting the force jumps and charge
transfer on normal load. Here, stick-slip dynamics arises as a competition
between the visco-elastic and plastic deformation time scales and that due to
the pull speed with contact charging playing a minor role. Our model provides
an alternate basis for explaining most experimental results without ascribing
friction to contact charging.Comment: 8 pages, 4 figures, To be appeared in Physical Review
Interference measurements of non-Abelian e/4 & Abelian e/2 quasiparticle braiding
The quantum Hall states at filling factors and are expected
to have Abelian charge quasiparticles and non-Abelian charge
quasiparticles. For the first time we report experimental evidence for the
non-Abelian nature of excitations at and examine the fermion parity,
a topological quantum number of an even number of non-Abelian quasiparticles,
by measuring resistance oscillations as a function of magnetic field in
Fabry-P\'erot interferometers using new high purity heterostructures. The phase
of observed oscillations is reproducible and stable over long times
(hours) near and , indicating stability of the fermion parity.
When phase fluctuations are observed, they are predominantly phase flips,
consistent with fermion parity change. We also examine lower-frequency
oscillations attributable to Abelian interference processes in both states.
Taken together, these results constitute new evidence for the non-Abelian
nature of quasiparticles; the observed life-time of their combined
fermion parity further strengthens the case for their utility for topological
quantum computation.Comment: A significantly revised version; 54 double-column pages containing 14
pages of main text + Supplementary Materials. The figures, which include a
number of new figures, are now incorporated into the tex
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