51 research outputs found
Vortex Mass in a Superfluid
We consider the inertial mass of a vortex in a superfluid. We obtain a vortex
mass that is well defined and is determined microscopically and
self-consistently by the elementary excitation energy of the kelvon
quasiparticle localised within the vortex core. The obtained result for the
vortex mass is found to be consistent with experimental observations on
superfluid quantum gases and vortex rings in water. We propose a method to
measure the inertial rest mass and Berry phase of a vortex in superfluid Bose
and Fermi gases.Comment: 12 pages, 1 figur
Introduction to topological quantum computation with non-Abelian anyons
Topological quantum computers promise a fault tolerant means to perform
quantum computation. Topological quantum computers use particles with exotic
exchange statistics called non-Abelian anyons, and the simplest anyon model
which allows for universal quantum computation by particle exchange or braiding
alone is the Fibonacci anyon model. One classically hard problem that can be
solved efficiently using quantum computation is finding the value of the Jones
polynomial of knots at roots of unity. We aim to provide a pedagogical,
self-contained, review of topological quantum computation with Fibonacci
anyons, from the braiding statistics and matrices to the layout of such a
computer and the compiling of braids to perform specific operations. Then we
use a simulation of a topological quantum computer to explicitly demonstrate a
quantum computation using Fibonacci anyons, evaluating the Jones polynomial of
a selection of simple knots. In addition to simulating a modular circuit-style
quantum algorithm, we also show how the magnitude of the Jones polynomial at
specific points could be obtained exactly using Fibonacci or Ising anyons. Such
an exact algorithm seems ideally suited for a proof of concept demonstration of
a topological quantum computer.Comment: 51 pages, 51 figure
Emergence of order from turbulence in an isolated planar superfluid
We study the relaxation dynamics of an isolated zero temperature
quasi-two-dimensional superfluid Bose-Einstein condensate (BEC) that is
imprinted with a spatially random distribution of quantum vortices. Following a
period of vortex annihilation, we find that the remaining vortices
self-organise into two macroscopic coherent `Onsager vortex' clusters that are
stable indefinitely. We demonstrate that this occurs due to a novel physical
mechanism --- the evaporative heating of the vortices --- that results in a
negative temperature phase transition in the vortex degrees of freedom. At the
end of our simulations the system is trapped in a non-thermal state. Our
computational results provide a pathway to observing Onsager vortex states in a
superfluid Bose gas.Comment: 10 pages, 7 figure
Hong-Ou-Mandel-like two-droplet correlations
We present a numerical study of two-droplet pair correlations for in-phase
droplets walking on a vibrating bath. Two such walkers are launched towards a
common origin. As they approach, their carrier waves may overlap and the
droplets have a non-zero probability of forming a two-droplet bound state. The
likelihood of such pairing is quantified by measuring the probability of
finding the droplets in a bound state at late times. Three generic types of
two-droplet correlations are observed: promenading, orbiting and chasing pair
of walkers. For certain parameters, the droplets may become correlated for
certain initial path differences and remain uncorrelated for others, while in
other cases the droplets may never produce droplet pairs. These observations
pave the way for further studies of strongly correlated many-droplet behaviors
in the hydrodynamical quantum analogs of bouncing and walking droplets.Comment: 8 pages, 5 figure
Braiding and fusion of non-Abelian vortex anyons
We demonstrate that certain vortices in spinor Bose-Einstein condensates are
non-Abelian anyons and may be useful for topological quantum computation. We
perform numerical experiments of controllable braiding and fusion of such
vortices, implementing the actions required for manipulating topological
qubits. Our results suggest that a new platform for topological quantum
information processing could potentially be developed by harnessing non-Abelian
vortex anyons in spinor Bose-Einstein condensates.Comment: 16 pages, 3 figures, 6 supplementary figures; added details of the
H-charge, J. K. Slingerland added to author lis
Atomic diffraction in counter-propagating Gaussian pulses of laser light
We present an analysis of atomic diffraction due to the interaction of an
atomic beam with a pair of Gaussian light pulses. We derive a simple analytical
expression for the populations in different diffraction orders. The validity of
the obtained solution extends beyond the Raman-Nath regime, where the kinetic
energy associated with different diffraction peaks is neglected, into the
so-called channeling regime where accurate analytical expressions have not
previously been available for the diffraction. Comparison with experimental
results and exact numerical solutions demonstrate the validity of our
analytical formula.Comment: 6 pages, 5 figure
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