739 research outputs found
Bulk and edge quasihole tunneling amplitudes in the Laughlin state
The tunneling between the Laughlin state and its quasihole excitations are
studied by using the Jack polynomial. We find a universal analytical formula
for the tunneling amplitude, which can describe both bulk and edge quasihole
excitations. The asymptotic behavior of the tunneling amplitude reveals the
difference and the crossover between bulk and edge states. The effects of the
realistic coulomb interaction with a background-charge confinement potential
and disorder are also discussed. The stability of the tunneling amplitude
manifests the topological nature of fractional quantum Hall liquids.Comment: 9 pages, 1 figure
Effect of Osmotic Dehydration as a Pre -Treatment on Air Fried Sweet Potato (Ipomoea batatas) Chips
Air frying is a modern frying technique that promises low oil content of fried products. However, the main limitation of air frying is that it requires a longer operating time than deep fat frying. Previous studies found that osmotic dehydration is beneficial as frying pre-treatment to improve the quality of fried products and reduce frying time, but to date, there is no study investigating its application in air frying. Therefore, this study aims to examine the effect of osmotic dehydration as pre-treatment on the quality of air-fried sweet potato chips. Sweet potatoes were cut into slices with the same thickness, and then soaked in distilled water, 5% sodium chloride solution, and 10% sodium chloride solution for one hour. The potato slices were then air fried at two temperatures: 160˚ and 180˚C for 3, 6, 9, 12, and 15 minutes. Then, moisture content, colour, texture, diameter shrinkage and thickness expansion were analysed. The moisture content of air fried chips decreased with the increasing of frying time. The osmo-dehydrated sample showed lower moisture content which could the reduce frying time from 12 mins to 9 mins at 160ºC. Osmo-dehydrated sweet potato slices produce paler chips, but the treatment preserved the red and yellow colour of the sample. Air fried sweet potatoes that were osmotically dehydrated samples shrank more in diameter than the control samples. The increased thickness of chips was caused by crust formation and the bubbles formed at the surface due to the barrier formed by the tight surface, resulting in vapour expansion inside the pores of the chips. The hardness of pre-treated chips increased significantly with decreasing moisture content. Using osmotic dehydration pre-treatment in the air frying process can yield promising results in less frying time and better retention in terms of red and yellow colour
Ground state and edge excitations of quantum Hall liquid at filling factor 2/3
We present a numerical study of fractional quantum Hall liquid at Landau
level filling factor in a microscopic model including long-range
Coulomb interaction and edge confining potential, based on the disc geometry.
We find the ground state is accurately described by the particle-hole conjugate
of a Laughlin state. We also find there are two counter-propagating
edge modes, and the velocity of the forward-propagating mode is larger than the
backward-propagating mode. The velocities have opposite responses to the change
of the background confinement potential. On the other hand changing the
two-body Coulomb potential has qualitatively the same effect on the velocities;
for example we find increasing layer thickness (which softens of the Coulomb
interaction) reduces both the forward mode and the backward mode velocities.Comment: 12 pages, 13 figure
Fractional quantum Hall effect at : Ground states, non-Abelian quasiholes, and edge modes in a microscopic model
We present a comprehensive numerical study of a microscopic model of the
fractional quantum Hall system at filling fraction , based on the
disc geometry. Our model includes Coulomb interaction and a semi-realistic
confining potential. We also mix in some three-body interaction in some cases
to help elucidate the physics. We obtain a phase diagram, discuss the
conditions under which the ground state can be described by the Moore-Read
state, and study its competition with neighboring stripe phases. We also study
quasihole excitations and edge excitations in the Moore-Read--like state. From
the evolution of edge spectrum, we obtain the velocities of the charge and
neutral edge modes, which turn out to be very different. This separation of
velocities is a source of decoherence for a non-Abelian quasihole/quasiparticle
(with charge ) when propagating at the edge; using numbers obtained
from a specific set of parameters we estimate the decoherence length to be
around four microns. This sets an upper bound for the separation of the two
point contacts in a double point contact interferometer, designed to detect the
non-Abelian nature of such quasiparticles. We also find a state that is a
potential candidate for the recently proposed anti-Pfaffian state. We find the
speculated anti-Pfaffian state is favored in weak confinement (smooth edge)
while the Moore-Read Pfaffian state is favored in strong confinement (sharp
edge).Comment: 15 pages, 9 figures; Estimate of e/4 quasiparticle/hole coherence
length when propagating along the edge modified in response to a recent
revision of Ref. 25, and minor changes elsewher
The Universal Edge Physics in Fractional Quantum Hall Liquids
The chiral Luttinger liquid theory for fractional quantum Hall edge transport
predicts universal power-law behavior in the current-voltage (-)
characteristics for electrons tunneling into the edge. However, it has not been
unambiguously observed in experiments in two-dimensional electron gases based
on GaAs/GaAlAs heterostructures or quantum wells. One plausible cause is the
fractional quantum Hall edge reconstruction, which introduces non-chiral edge
modes. The coupling between counterpropagating edge modes can modify the
exponent of the - characteristics. By comparing the fractional
quantum Hall states in modulation-doped semiconductor devices and in graphene
devices, we show that the graphene-based systems have an experimental
accessible parameter region to avoid the edge reconstruction, which is suitable
for the exploration of the universal edge tunneling exponent predicted by the
chiral Luttinger liquid theory.Comment: 7 pages, 6 figure
Asymptotic sign free in interacting fermion models
As an intrinsically-unbiased approach, quantum Monte Carlo (QMC) is of vital
importance in understanding correlated phases of matter. Unfortunately, it
often suffers notorious sign problem when simulating interacting fermion
models. Here, we show for the first time that there exist interacting fermion
models whose sign problem becomes less severe for larger system sizes and
eventually disappears in the thermodynamic limit, which we dub as "asymptotic
sign free". We demonstrate asymptotically-free sign in determinant QMC for
various interacting models. Moreover, based on renormalization-group-like ideas
we propose a heuristic understanding of the feature of asymptotic sign free. We
believe that asymptotic sign free behavior could shed new lights to deepening
our understanding of sign problem. More importantly, it can provide a promising
way to decipher intriguing physics in correlated models which were
conventionally thought not accessible by QMC.Comment: 4.5 pages plus supplemental material, 5 figure
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