Thierry Giamarchi (U. of Geneva)

1/4/11, 10:50 AM

Localized spin systems, and in particular dimer systems,
provide a fantastic laboratory to study
the interplay between quantum effects and the interaction
between excitations. Magnetic field and temperature allow an
excellent control on the density of excitations and various
very efficient probes such as neutrons and NMR are available.
They can thus be used as ``quantum simulators'' to...

Daniel Arovas (UC San Diego)
(UC San Diego)

1/4/11, 11:50 AM

I will summarize some recent developments in the study of
quantum entanglement spectra. I will also discuss work
performed in collaboration with R. Thomale and A. Bernevig
on entanglement spectra in spin chains. Typically,
bipartite entanglement entropy and spectra have been studied
in the case of spatial partitions, i.e. A denotes the left
half of a spin chain and B the right half,...

Ehud Altman (Weizman Institute)

1/4/11, 2:30 PM

Bosons in a one dimensional chain can form two gapped phases
at integer filling, the Mott and Haldane insulators. The
critical point separating these two phases is gapped out by
a perturbation breaking lattice inversion symmetry. I will
show that encircling the critical point adiabatically in the
plane of the tuning parameter and the inversion symmetry
breaking perturbation, entails...

Victor Galitski (Joint Quantum Institute and Physics Department, U. of Maryland)
(U. of Maryland)

1/4/11, 3:20 PM

In this talk, I will review our recent work on a
Lie-algebraic approach to various quantum-mechanical
problems. The first part will be devoted to non-equilibrium
driven dynamics of closed quantum systems. It will be
emphasized that mathematically a non-equilibrium
Hamiltonian represents a trajectory in a Lie algebra, while
the evolution operator is a trajectory in a Lie group
generated...

Boris Svistunov (U.Mass Amherst)

1/5/11, 10:00 AM

Monte Carlo sampling of the Feynman diagrammatic series can
be used for tackling hard fermionic quantum many-body
problems in the thermodynamic limit. I will introduce the
technique and present illustrative results for the repulsive
Hubbard model in the correlated Fermi liquid regime, as well
as the results for the equation of state for the system of
resonant fermions in the regime of...

Asle Sudbo (NTNU Trondheim)
(NTNU Trondheim)

1/5/11, 12:00 PM

We consider a three-dimensional lattice $U(1) \times U(1)$
and $[U(1)]^N$ superconductors in the London limit, with
individually conserved condensates. The $U(1) \times U(1)$
problem, generically, has two types of intercomponent
interactions of different characters. First, the condensates
are interacting via a minimal coupling to the same
fluctuating gauge field. A second type of...

Victor Moshchalkov (KU Leuven)
(KU Leuven)

1/5/11, 2:40 PM

Yoshiteru Maeno (Kyoto U)
(Kyoto U.)

1/5/11, 3:30 PM

We devise a new proximity junction configuration where an
/s/-wave superconductivity and the superconductivity of Sr_2
RuO_4 interfere with each other. In order to explain the
observed extraordinary temperature dependence of the
critical current in a Pb/Ru/Sr_2 RuO_4 junction, we propose
a competition effect involving topologically distinct
superconducting phases around Ru inclusions....

Beena Kalisky (Stanford U.)
(Stanford)

1/5/11, 4:30 PM

We use scanning SQUID microscopy to investigate local
variations in the diamagnetic susceptibility in twinned
samples of two families of high temperature superconductors.
In Ba(Fe1-xCox)2As2 of the pnictides we observe increased
diamagnetic susceptibility on the twin boundaries in
underdoped, but not overdoped, single crystals. Vortex
behavior near the twin boundaries reveals that...

Ophir Auslaender (Technion - Israel Institute of Technology)

1/5/11, 5:10 PM

We use a low temperature magnetic force microscope (MFM) to
study
superconductors. The interaction between the magnetic tip and
individual vortices allows us to both image vortices and to
manipulate
them. The manipulation results depend on sample thickness
and on the
superconducting properties. Here I concentrate on YBCO
samples and on
an underdoped pnictide sample. In thin films, if...

Olexei Motrunich (Caltech)
(Caltech)

1/6/11, 10:50 AM

I will present our Quantum Monte Carlo studies of hard-core
boson Hamiltonians with ring-only interactions on the 2D
square lattice searching for a so-called Excitonic Bose
Liquid (EBL). This phase, which can be viewed as a special
type of "Bose metal", had eluded numerical realization since
the first proposal a decade ago, as the original model
showed either charge-order at...

Boris Spivak (U. of Washington)
(University of Washington)

1/6/11, 11:50 AM

An overview of the measured transport properties of the two
dimensional electron fluids in high
mobility semiconductor devices with low electron densities
is presented as well as some of the theories
that have been proposed to account for them. Many features
of the observations are not easily
reconciled with a description based on the well understood
physics of weakly interacting...

Boris Spivak (U. of Washington)
(University of Washington)

1/6/11, 2:40 PM

he Pfaffian phase of electrons in the proximity of a
half-filled Landau level is understood to be a p+ip
superconductor of composite fermions. We consider the
properties of this paired quantum Hall phase when the
pairing scale is small, i.e. in the weak-coupling, BCS,
limit, where the coherence length is much larger than the
charge screening length. We find that, as in a Type...

James Sauls (Northwestern University)
(Northwestern University)

1/6/11, 3:30 PM

Broken symmetries in bulk condensed matter systems have
implications for the spec-
trum of Fermionic excitations bound to surfaces and
topological defects. I discuss
the relationship between the broken symmetry of the ground
state and the topolog-
ical nature of bound states at surfaces, domain walls and
topological line defects.
In addition to the Fermionic spectrum, strong...

Paul Goldbart (U. of Illions Urbana Champaign)
(University of Illions Urbana Champaign)

1/6/11, 4:30 PM

The self-organization of a Bose-Einstein condensate in a
transversely pumped optical cavity is a process akin to
crystallization: when pumped by a laser of sufficient
intensity, the coupled matter and light fields evolve,
spontaneously, into a spatially modulated pattern, or
crystal, whose lattice structure is dictated by the geometry
of the cavity. In cavities having multiple...

Charles Reichhardt (Los Alamos National Laboratory)
(Los Alamos National Laboratory)

1/7/11, 10:00 AM

I will give an overview of how systems with competing
interactions such as repulsion on one scale and attraction
on another can generically give rise rise to bubble, stripe,
clump, and other patterns. The same patterns can occur for
systems with purely repulsive interactions provided there
are two or more distinct length scales in the potential. I
will show how these patterns can arise...

Joel Moore (Berkeley)
(Berkeley)

1/7/11, 10:50 AM

The original definition of a topological insulator was as a
time-reversal-symmetric insulator in which spin-orbit
coupling leads to protected metallic edge or surface states.
An alternate definition comes from considering the effect
of a small perturbation that breaks the symmetry and gaps
the surfaces; then the material can be viewed as having a
quantized magnetoelectric effect. We...

Victor Gurarie (U of Colorado Boulder)

1/7/11, 11:50 AM

We develop a method to characterize interacting topological
insulators with single particle Green's functions. If the
interactions are switched off, it reproduces the known
behavior of noninteracting topological insulators, in
particular the existence of the edge states at their
boundary. At the same time, the method explains why
topological insulators, once the interactions are turned...

Aurel Bulgac (U. of Washington)
(University of Washington)

1/7/11, 2:30 PM

Superfluidity and superconductivity are remarkable
manifestations of quantum coherence at a macroscopic scale.
The dynamics of superfluids has dominated the study of these
systems for decades now, but a comprehensive theoretical
framework is still lacking. We introduce a local extension
of the time-dependent density functional theory to describe
the dynamics of fermionic superfluids....

297.
Multiband superconductivity at high magnetic fields and the FFLO instability in ferropnictides.

Alex Gurevich (Florida State U)

1/7/11, 3:20 PM

Low carrier densities and short coherence lengths in
semi-metallic ferropnictide superconductors can result in
exotic behaviors at strong magnetic fields due to the
interplay of multiband superconductivity, unconventional
pairing symmetry and Zeeman and orbital pairbreaking. In
this talk I discuss how these effects manifest
themselves in the anomalous temperature dependence of the
upper...

Oskar Vafek (Florida State U)

1/7/11, 4:20 PM

Many-body instabilities of the half-filled honeycomb bilayer are
studied using weak-coupling renormalization group (RG) as
well as
strong-coupling expansion [1,2]. For spinless fermions,
there are
4 independent four-fermion contact couplings. Generally, we find
runaway RG flows which we associate with ordering
tendencies. The
broken symmetry state is typically a gapped insulator...

Walter Hofstetter (Goethe-Universität Frankfurt)

1/7/11, 5:10 PM

Cold atoms in optical lattices offer a new laboratory for
the study of
strong correlation phenomena.I will focus on two recent
developments:
i) We report the first detection of the Higgs-type amplitude
mode using Bragg spectroscopy
in a strongly interacting Bose condensate in an optical
lattice. By the comparison of our experimental data
with a spatially resolved, dynamical...

Edouard Sonin (Racah Inst. Hebrew University of Jerusalem)
(Racah Inst. Hebrew University of Jerusalem)

1/8/11, 10:00 AM

Possible domain structure in p-wave superconductors with
broken time-reversal symmetry is intensively discussed in
literature in connection with failed experimental attempts
to detect stray magnetic fields in Sr2RuO4, which were
theoretical predicted for these materials. This puts in
question the very idea of p-wave pairing. The lecture
starts from the short overview of the...

Alexander Balatsky (LANL)
(Los Alamos National Laboratory)

Recently a new single-layer material—graphene—has been
discovered.
This is a material where Dirac points in the fermionic
spectrum lead
to very unusual properties, including transport and impurity
states.
I will argue that these properties are not unique to
graphene and in
fact are a direct consequence of the Dirac spectrum in the
fermionic
excitation sector. Strong similarities...

Alex Gurevich (National High Magnetic Field Laboratory)
(National High Magnetic Field Laboratory)

Ophir Auslaender (Technion - Israel Institute of Technology)
(Technion - Israel Institute of Technology)

Alex Gurevich (National High Magnetic Field Laboratory)
(National High Magnetic Field Laboratory)