12,924 research outputs found
Robustness of Majorana Fermion induced Fractional Josephson Effect
It is shown in previous works that the coupling between two Majorana end
states in superconducting quantum wires leads to fractional Josephson effect.
However, in realistic experimental conditions, multiple bands of the wires are
occupied and the Majorana end states are accompanied by other fermionic end
states. This raises the question concerning the robustness of fractional
Josephson effect in these situations. In this work, we show that the absence of
the avoided energy crossing which gives rise to the fractional Josephson effect
is robust, even when the Majorana fermions are coupled with arbitrary strengths
to other fermions. Moreover, we calculate the temperature dependence of the
fractional Josephson current and show that it is suppressed by thermal
excitations to the other fermion bound states.Comment: 4+ pages, 3 figure
The LuckyCam Survey for Very Low Mass Binaries II: 13 new M4.5-M6.0 Binaries
We present results from a high-angular-resolution survey of 78 very low mass
(VLM) binary systems with 6.0 = 0.15
arcsec/yr. 21 VLM binaries were detected, 13 of them new discoveries. The new
binary systems range in separation between 0.18 arcsec and 1.3 arcsec. The
distance-corrected binary fraction is 13.5% (+6.5%/-4%), in agreement with
previous results. 9 of the new binary systems have orbital radii > 10 AU,
including a new wide VLM binary with 27 AU projected orbital separation. One of
the new systems forms two components of a 2300 AU separation triple system. We
find that the orbital radius distribution of the binaries with V-K < 6.5 in
this survey appears to be different from that of redder (lower-mass) objects,
suggesting a possible rapid change in the orbital radius distribution at around
the M5 spectral type. The target sample was also selected to investigate X-ray
activity among VLM binaries. There is no detectable correlation between excess
X-Ray emission and the frequency and binary properties of the VLM systems.Comment: 11 pages, 8 figures. Submitted to MNRA
Counter-Intuitive Vacuum-Stimulated Raman Scattering
Vacuum-stimulated Raman scattering in strongly coupled atom-cavity systems
allows one to generate free-running single photon pulses on demand. Most
properties of the emitted photons are well defined, provided spontaneous
emission processes do not contribute. Therefore, electronic excitation of the
atom must not occur, which is assured for a system adiabatically following a
dark state during the photon-generation process. We experimentally investigate
the conditions that must be met for adiabatic following in a time-of-flight
driven system, with atoms passing through a cavity and a pump beam oriented
transverse to the cavity axis. From our results, we infer the optimal intensity
and relative pump-beam position with respect to the cavity axis.Comment: 4 pages, 4 figure
Wave attenuation and dispersion due to floating ice covers
Experiments investigating the attenuation and dispersion of surface waves in
a variety of ice covers are performed using a refrigerated wave flume. The ice
conditions tested in the experiments cover naturally occurring combinations of
continuous, fragmented, pancake and grease ice. Attenuation rates are shown to
be a function of ice thickness, wave frequency, and the general rigidity of the
ice cover. Dispersion changes were minor except for large wavelength increases
when continuous covers were tested. Results are verified and compared with
existing literature to show the extended range of investigation in terms of
incident wave frequency and ice conditions
An Attempt to Demonstrate Neutralizing Antibodies to the Mammary Tumour âMilk Agentâ in Mice
Thinking beyond the hybrid:âactually-existingâ cities âafter neoliberalismâ in Boyle <i>et al.</i>
In their article, âThe spatialities of actually existing neoliberalism in Glasgow, 1977 to presentâ, Mark Boyle, Christopher McWilliams and Gareth Rice (2008) usefully problematise our current understanding of neoliberal urbanism. Our response is aimed at developing a sympathetic but critical approach to Boyle et al's understanding of neoliberal urbanism as illustrated by the Glasgow example. In particular, the counterposing by Boyle et al of a 'hybrid, mutant' model to a 'pure' model of neoliberalism for us misrepresents existing models of neoliberalism as a perfectly finished object rather than a roughly mottled process. That they do not identify any âpureâ model leads them to create a straw construct against which they can claim a more sophisticated, refined approach to the messiness of neoliberal urbanism. In contrast, we view neoliberalism as a contested and unstable response to accumulation crises at various scales of analysis
Quantum fluctuations in coupled dark solitons in trapped Bose-Einstein condensates
We show that the quantum fluctuations associated with the Bogoliubov
quasiparticle vacuum can be strongly concentrated inside dark solitons in a
trapped Bose Einstein condensate. We identify a finite number of anomalous
modes that are responsible for such quantum phenomena. The fluctuations in
these anomalous modes correspond to the `zero-point' oscillations in coupled
dark solitons.Comment: 4 pages, 3 figure
A Generalization of the Goldberg-Sachs Theorem and its Consequences
The Goldberg-Sachs theorem is generalized for all four-dimensional manifolds
endowed with torsion-free connection compatible with the metric, the treatment
includes all signatures as well as complex manifolds. It is shown that when the
Weyl tensor is algebraically special severe geometric restrictions are imposed.
In particular it is demonstrated that the simple self-dual eigenbivectors of
the Weyl tensor generate integrable isotropic planes. Another result obtained
here is that if the self-dual part of the Weyl tensor vanishes in a Ricci-flat
manifold of (2,2) signature the manifold must be Calabi-Yau or symplectic and
admits a solution for the source-free Einstein-Maxwell equations.Comment: 14 pages. This version matches the published on
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