7,923 research outputs found
Positive and negative Hanbury-Brown and Twiss correlations in normal metal-superconducting devices
In the light of the recent analogs of the Hanbury--Brown and Twiss
experiments in mesoscopic beam splitters, negative current noise correlations
are recalled to be the consequence of an exclusion principle. Here, positive
(bosonic) correlations are shown to exist in a fermionic system, composed of a
superconductor connected to two normal reservoirs. In the Andreev regime, the
correlations can either be positive or negative depending on the reflection
coefficient of the beam splitter. For biases beyond the gap, the transmission
of quasiparticles favors fermionic correlations. The presence of disorder
enhances positive noise correlations. Potential experimental applications are
discussed.Comment: 4 pages, 3 figures, RevTeX, revised versio
Continuous-Time Consensus under Non-Instantaneous Reciprocity
We consider continuous-time consensus systems whose interactions satisfy a
form or reciprocity that is not instantaneous, but happens over time. We show
that these systems have certain desirable properties: They always converge
independently of the specific interactions taking place and there exist simple
conditions on the interactions for two agents to converge to the same value.
This was until now only known for systems with instantaneous reciprocity. These
result are of particular relevance when analyzing systems where interactions
are a priori unknown, being for example endogenously determined or random. We
apply our results to an instance of such systems.Comment: 12 pages, 4 figure
Remnants of galactic subhalos and their impact on indirect dark-matter searches
Dark-matter subhalos, predicted in large numbers in the cold-dark-matter scenario, should have an impact on dark-matter-particle searches. Recent results show that tidal disruption of these objects in computer simulations is overefficient due to numerical artifacts and resolution effects. Accounting for these results, we re-estimated the subhalo abundance in the Milky Way using semianalytical techniques. In particular, we showed that the boost factor for gamma rays and cosmic-ray antiprotons is increased by roughly a factor of twoJ.L. and M.S. are partly supported by the Agence Nationale pour la Recherche (ANR)
Project No. ANR-18-CE31-0006, the Origines, Constituants, et EVolution de l’Univers (OCEVU) Labex (No. ANR-11-LABX-0060), the CNRS IN2P3-Theory/INSU-PNHE-PNCG project “Galactic Dark Matter,” and the European Union’s Horizon 2020 Research and Innovation Program under Marie Skłodowska-Curie Grant Agreements No. 690575 and No. 674896, in addition to recurrent funding by the Centre National de la Recherche Scientifique (CNRS) and the University of Montpellier. T.L. is supported by the European Union’s Horizon 2020 Research and Innovation Program under the Marie Skłodowska-Curie grant agreement No. 713366. The work of TL was also supported by the Spanish Agencia Estatal de Investigación through grants PGC2018-095161-B-I00, IFT Centro de Excelencia Severo Ochoa SEV-2016-0597, and Red Consolider MultiDark FPA2017-90566-RED
3D Directional Coupler for Impulse UWB: 3D Electromagnetic Simulation and Prototyping
The AWS Group developed a UWB radar and UWB transceiver for indoor people location and tracking. A radar concept has been developed. This paper will describe step by step the realization of a UWB directional coupler with a novel 3-D architecture. This paper gives a walkthrough of our design of the 3-D directional coupler
Chiral CP^2 skyrmions in three-band superconductors
It is shown that under certain conditions, three-component superconductors
(and in particular three-band systems) allow stable topological defects
different from vortices. We demonstrate the existence of these excitations,
characterized by a topological invariant, in models for three-component
superconductors with broken time reversal symmetry. We term these topological
defects "chiral skyrmions", where "chiral" refers to the fact that
due to broken time reversal symmetry, these defects come in inequivalent left-
and right-handed versions. In certain cases these objects are energetically
cheaper than vortices and should be induced by an applied magnetic field. In
other situations these skyrmions are metastable states, which can be produced
by a quench. Observation of these defects can signal broken time reversal
symmetry in three-band superconductors or in Josephson-coupled bilayers of
and s-wave superconductors.Comment: minor presentation changes; replaced journal version; 30 pages, 21
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