Luttinger Liquid Physics and Spin-Flip Scattering on Helical Edges. (arXiv:1110.3322v1 [cond-mat.str-el])

We investigate electronic correlation effects on edge states of quantum spin
Hall insulators within the Kane-Mele-Hubbard model by means of quantum Monte
Carlo simulations. In accordance with Luttinger liquid theory, we find dominant
transverse spin fluctuations with an interaction dependent power law and the
expected doping dependence. For strong electronic correlations, bulk states
become important, and high-energy spectral features beyond Luttinger liquid
theory emerge. Inelastic spin-flip scattering leads to graphene-like edge state
signatures, and transfers spectral weight from low to high energies causing a
suppression of charge transport.

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FPEOS: A First-Principles Equation of State Table of Deuterium for Inertial Confinement Fusion Applications. (arXiv:1110.0001v1 [cond-mat.mtrl-sci])

Understanding and designing inertial confinement fusion (ICF) implosions
through radiation-hydrodynamics simulations rely on the accurate knowledge of
the equation of state (EOS) of the deuterium and tritium fuels. To minimize the
drive energy for ignition, the imploding shell of DT fuel must be kept as cold
as possible. Such low-adiabat ICF implosions can access to coupled and
degenerate plasma conditions, in which the analytical or chemical EOS models
become inaccurate. Using the path-integral Monte Carlo (PIMC) simulations we
have derived a first-principles EOS (FPEOS) table of deuterium that covers
typical ICF fuel conditions at densities ranging from 0.002 to 1596 g/cm3 and
temperatures of 1.35 eV to 5.5 keV. We report the internal energy and the
pressure, and discuss the structure of the plasma in terms of pair-correlation
functions. When compared with the widely used SESAME table and the revised
Kerley03 table, discrepancies in the internal energy and in the pressure are
identified for moderately coupled and degenerate plasma conditions. In contrast
to the SESAME table, the revised Kerley03 table is in better agreement with our
FPEOS results over a wide range of densities and temperatures. Although subtle
differences still exist for lower temperatures (T < 10 eV) and moderate
densities (1 to 10 g/cc), hydrodynamics simulations of cryogenic ICF implosions
using the FPEOS table and the Kerley03 table have resulted in similar results
for the peak density, areal density ({\rho}R), and neutron yield, which are
significantly different from the SESAME simulations.

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Detecting Berry curvature in the dynamical Hall effect. (arXiv:1109.6024v1 [cond-mat.stat-mech])

Geometric phases in quantum mechanics play an extraordinary role in
broadening our understanding of fundamental significance of geometry in nature.
One of the best known examples is the Berry phase \cite{berry_84}, which
naturally emerges in quantum adiabatic evolution. So far the applicability and
measurements of the Berry phase were limited to systems of weakly interacting
quasi-particles, where interference experiments are feasible. Here we show how
one can go beyond this limitation and observe the Berry curvature (and hence
the Berry phase) in generic systems as a non-adiabatic response of physical
observables to quench velocity. These results can be interpreted as a dynamical
Hall effect in a generic parameter space. We illustrate our findings with two
examples of an isolated spin and a Heisenberg spin chain in a time-dependnt
magnetic field. In both cases we observe quantization of the dynamical response
similar to the quantum Hall effect.

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Spin and Majorana polarization in topological superconducting wires. (arXiv:1109.5697v1 [cond-mat.mes-hall])

We study a one-dimensional wire with strong spin-orbit coupling, which
supports Majorana fermions when subject to a Zeeman magnetic field and in
proximity of a superconductor. We evaluate the local density of states, as well
as the spin polarization in this system using an exact numerical
diagonalization approach. Moreover, we define and calculate a local “Majorana
polarization” and “Majorana density”. We find that the spatial dependence of
the Majorana polarization is proportional to that of the spin polarization
parallel to the chain and we propose to test the presence of Majorana fermions
in a 1D system by a spin-polarized density of states measurement. We also
describe the effects of disorder on the Majorana polarization of the system.

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Localization of gauge fields and Maxwell-Chern-Simons theory. (arXiv:1109.5694v1 [hep-th])

We propose an explicit model, where an axionic domain wall dynamically
localizes a U(1)-component of a nonabelian gauge theory living in a 3+1
dimensional bulk. The effective theory on the wall is 2+1d Maxwell-Chern-Simons
theory with a compact U(1) gauge group. This setup allows us to understand all
key properties of MCS theory in terms of the dynamics of the underlying 3+1
dimensional gauge theory. Our findings can also shed some light on branes in
supersymmetric gluodynamics.

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RKKY interaction in SDW phase of iron-based superconductors. (arXiv:1109.4643v1 [cond-mat.str-el])

Using the multiband model we analyze the Ruderman-Kittel-Kasuya-Yosida (RKKY)
interaction between the magnetic impurities in layered ferropnictide
superconductors. In the normal state the interaction is spin isotropic and is
dominated by the nesting features of the electron and hole bands separated by
the antiferromagnetic momentum, $ {\bf Q}_{AF}$ . In the AF state the RKKY
interaction maps into an effective anisotropic XXZ-type Heisenberg exchange
model. The anisotropy originates from the breaking of the spin-rotational
symmetry induced by the AF order and its strength depends on the size of the AF
gap and the structure of the folded Fermi surface. We discuss our results in
connection to the recent experiments.

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Random Sequential Renormalization and Agglomerative Percolation in Networks: Application to Erd”os-R’enyi and Scale-free Graphs. (arXiv:1109.4631v1 [cond-mat.stat-mech])

We study the statistical behavior under random sequential
renormalization(RSR) of several network models including Erd”os R’enyi (ER)
graphs, scale-free networks and an annealed model (AM) related to ER graphs. In
RSR the network is locally coarse grained by choosing at each renormalization
step a node at random and joining it to all its neighbors. Compared to previous
(quasi-)parallel renormalization methods [C.Song et.al], RSR allows a more
fine-grained analysis of the renormalization group (RG) flow, and unravels new
features, that were not discussed in the previous analyses. In particular we
find that all networks exhibit a second order transition in their RG flow. This
phase transition is associated with the emergence of a giant hub and can be
viewed as a new variant of percolation, called agglomerative percolation. We
claim that this transition exists also in previous graph renormalization
schemes and explains some of the scaling laws seen there. For critical trees it
happens as N/N0 -> 0 in the limit of large systems (where N0 is the initial
size of the graph and N its size at a given RSR step). In contrast, it happens
at finite N/N0 in sparse ER graphs and in the annealed model, while it happens
for N/N0 -> 1 on scale-free networks. Critical exponents seem to depend on the
type of the graph but not on the average degree and obey usual scaling
relations for percolation phenomena. For the annealed model they agree with the
exponents obtained from a mean-field theory. At late times, the networks
exhibit a star-like structure in agreement with the results of Radicchi et. al.
While degree distributions are of main interest when regarding the scheme as
network renormalization, mass distributions (which are more relevant when
considering ‘supernodes’ as clusters) are much easier to study using the fast
Newman-Ziff algorithm for percolation, allowing us to obtain very high
statistics.

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Theory of light amplification in active fishnet metamaterials. (arXiv:1109.4411v1 [physics.optics])

We establish a theory that traces light amplification in an active
double-fishnet metamaterial back to its microscopic origins. Based on ab initio
calculations of the light/plasmon fields we extract energy rates and conversion
efficiencies associated with gain/loss channels directly from Poynting’s
theorem. We find that for the negative refactive index mode both radiative loss
and gain outweigh resistive loss by more than a factor of two, opening a broad
window of steady-state amplification (free of instabilities) accessible even
when a gain reduction close to the metal is taken into account.

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Doping a spin-orbit Mott Insulator: Topological Superconductivity from the Kitaev-Heisenberg Model and possible application to (Na2/Li2)IrO3. (arXiv:1109.4155v1 [cond-mat.str-el])

We study the effects of doping a Mott insulator on the honeycomb lattice
where spins interact via direction dependent Kitaev couplings J_K, and weak
antiferromagnetic Heisenberg couplings J. This model is known to have a spin
liquid ground state and may potentially be realized in correlated insulators
with strong spin orbit coupling. The effect of hole doping is studied within a
t-J-J_K model, treated using the SU(2) slave boson formulation, which correctly
captures the parent spin liquid. We find superconductor ground states with spin
triplet pairing that spontaneously break time reversal symmetry. Interestingly,
the pairing is qualitatively different at low and high dopings, and undergoes a
first order transition with doping. At high dopings, it is smoothly connected
to a paired state of electrons propagating with the underlying free particle
dispersion. However, at low dopings the dispersion is strongly influenced by
the magnetic exchange, and is entirely different from the free particle band
structure. Here the superconductivity is fully gapped and topological,
analogous to spin polarized electrons with px+ipy pairing. These results may be
relevant to honeycomb lattice iridates such as A2IrO3 (A=Li or Na) on doping.

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Entanglement Structure of Deconfined Quantum Critical Points. (arXiv:1109.3185v1 [cond-mat.str-el])

We study the entanglement properties of deconfined quantum critical points.
We show not only that these critical points may be distinguished by their
entanglement structure but also that they are in general more highly entangled
that conventional critical points. We primarily focus on computations of the
entanglement entropy of deconfined critical points in 2+1 dimensions, drawing
connections to topological entanglement entropy and a recent conjecture on the
monotonicity under RG flow of universal terms in the entanglement entropy. We
also consider in some detail a variety of issues surrounding the extraction of
universal terms in the entanglement entropy. Finally, we compare some of our
results to recent numerical simulations.

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