22,068 research outputs found
Comment on "BCS superconductivity of Dirac fermions in graphene layers"
Comment on "BCS superconductivity of Dirac fermions in graphene layers" by N.
B. Kopnin and E. B. Sonin [arXiv:0803.3772; Phys. Rev. Lett. 100, 246808
(2008)].Comment: 1.1 page
Kondo Quantum Criticality of Magnetic Adatoms in Graphene
We examine the exchange Hamiltonian for magnetic adatoms in graphene with
localized inner shell states. On symmetry grounds, we predict the existence of
a class of orbitals that lead to a distinct class of quantum critical points in
graphene, where the Kondo temperature scales as
near the critical coupling , and the local spin is effectively screened
by a \emph{super-ohmic} bath. For this class, the RKKY interaction decays
spatially with a fast power law . Away from half filling, we show
that the exchange coupling in graphene can be controlled across the quantum
critical region by gating. We propose that the vicinity of the Kondo quantum
critical point can be directly accessed with scanning tunneling probes and
gating.Comment: 4.1 pages, 3 figures. Added erratum correcting exponent nu=1/3. All
the other results remain vali
Tabulation of PVI Transcendents and Parametrization Formulas (August 17, 2011)
The critical and asymptotic behaviors of solutions of the sixth Painlev\'e
equation PVI, obtained in the framework of the monodromy preserving deformation
method, and their explicit parametrization in terms of monodromy data, are
tabulated.Comment: 30 pages, 1 figure; Nonlinearity 201
Superconducting states of pure and doped graphene
We study the superconducting phases of the two-dimensional honeycomb lattice
of graphene. We find two spin singlet pairing states, s-wave and an exotic
that is possible because of the special structure of the honeycomb
lattice. At half filling, the phase is gapless and superconductivity is
a hidden order. We discuss the possibility of a superconducting state in metal
coated graphene.Comment: 4 pages, 6 figure
Drops on soft solids: Free energy and double transition of contact angles
The equilibrium shape of liquid drops on elastic substrates is determined by
minimising elastic and capillary free energies, focusing on thick
incompressible substrates. The problem is governed by three length scales: the
size of the drop , the molecular size , and the ratio of surface tension
to elastic modulus . We show that the contact angles undergo two
transitions upon changing the substrates from rigid to soft. The microscopic
wetting angles deviate from Young's law when , while the
apparent macroscopic angle only changes in the very soft limit . The elastic deformations are worked out in the simplifying case where the
solid surface energy is assumed constant. The total free energy turns out lower
on softer substrates, consistent with recent experiments
High efficiency coupling of photon pairs in practice
Multi-photon and quantum communication experiments such as loophole-free Bell
tests and device independent quantum key distribution require entangled photon
sources which display high coupling efficiency. In this paper we put forward a
simple quantum theoretical model which allows the experimenter to design a
source with high pair coupling efficiency. In particular we apply this approach
to a situation where high coupling has not been previously obtained: we
demonstrate a symmetric coupling efficiency of more than 80% in a highly
frequency non-degenerate configuration. Furthermore, we demonstrate this
technique in a broad range of configurations, i.e. in continuous wave and
pulsed pump regimes, and for different nonlinear crystals
Kitchen-Sink Enlightenment: A Review of “Grace for Amateurs”
Excerpt: Here’s an honest admission: Several times while reading Lily Burana’s new book Grace for Amateurs: Field Notes on a Journey Back to Faith, I consulted the copyright page, confirming again that Grace for Amateurs was really published by Thomas Nelson, the notoriously evangelical (and, in my mind, notoriously traditional) press. After all, it wasn’t that long ago that Thomas Nelson asked another writer to remove the word “vagina” from her book, well aware that Christian readers would balk at language so closely associated with women and S-E-X. Would this same publisher be willing to support a memoir as edgy and progressive as Burana’s
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