Prof.
Carlos Sa de Melo
(Georgia Tech (USA))
21/01/2013, 10:50
I discuss the creation of parity violating Fermi superfluids in
the presence of non-Abelian gauge fields involving spin-orbit
coupling and crossed Zeeman fields. I focus on spin-orbit
coupling with equal Rashba and Dresselhaus (ERD)
strengths which has been realized experimentally in ultra-
cold atoms, but also discuss the case of arbitrary mixing of
Rashba and Dresselhaus (RD) and...
Prof.
Karyn Le Hur
(Ecole Polytechnique Palaiseau)
21/01/2013, 14:00
During the last decade, experiments have established the
existence of unconventional states of matter in a variety of
low-dimensional quantum systems. This includes
equilibrium states characterized by topological properties as
well as stationary states in and out of equilibrium situations.
In this Talk, we focus on topological phases of matter, their
experimental signatures, and...
Prof.
Georg Bruun
(Aarhus University)
22/01/2013, 10:00
I discuss the existence of long-lived repulsive as well as
attractive polarons in a strongly interacting Fermi gas. The
energy, lifetime, and quasiparticle residue of the polarons
are calculated, and I show show how they accurately
describe experimental data. Finally, I discuss possible
consequences of these results regarding observing itinerant
ferromagnetism in atomic gases
Mr
Miikka Heikkinen
(Aalto University)
22/01/2013, 14:00
We investigate exotic paired states of spin-polarized
Fermi gases in the dimensional crossover between
onedimensional and three-dimensional optical lattices. We
compute the finite temperature phase diagram of the system
along the dimensional crossover using real-space dynamical
mean-field theory in combination with the continuous-time
auxiliary field quantum Monte Carlo method. We find...
Dr
Gergely Szirmai
(Wigner Research Centre of the Hungarian Academy of Sciences, Budapest)
22/01/2013, 14:30
We describe the spin dynamics of the antiferromagnetic
Mott insulator ground state of high spin fermions on a 2-
dimensional hexagonal lattice. It was pointed out that
such multicomponent systems in 1 and 2 dimensions can
realize states without breaking the spin rotation
symmetry when the number of components is large
enough [1-3]. The low energy fluctuations on top of
these so...
Prof.
Achim Scwenk
(TU Darmstadt/EMMI)
23/01/2013, 10:00
Dr
Adrian Kantian
(University of Geneva)
23/01/2013, 14:00
Advances in cold gases physics are enabling experiments
involving the direct manipulation and observation of single-
or few-atom mobile impurities [1,2] within a many-body
quantum system, a topic of longstanding interest for
condensed matter theory, where it is related to studies of
e.g. conductivity and the X-ray edge problem.
In light of these developments we study the dynamics...
Prof.
Luca Salasnich
(Department of Physics, University of Padova)
24/01/2013, 10:00
We study theoretically the effects of spin-orbit coupling
on a two-spin-component ultracold atomic Fermi gas
along the BCS-BEC crossover of a Feshbach resonance.
We find that the condensate fraction of Cooper pairs
characterizes the crossover better than other quantities,
like the chemical potential or the pairing gap. We also
find that, due to the spin-orbit coupling, in...
Dr
Andrea Fischer
(University of Cambridge, Cavendish Laboratory)
24/01/2013, 10:30
We consider a gas of fermionic atoms conned to a quasi-
2D geometry by a strong harmonic confinement potential
in the transverse direction. For a two-component
population balanced system, we construct a mean field
theory for the BCS-BEC crossover, which correctly
renormalises the s-wave contact interaction and allows
infinitely many harmonic oscillator bands to be taken into...
Prof.
Jorge Dukelsky
(Instituto de Estructura de la Materia. CSIC.)
24/01/2013, 14:00
The exact solution of the SU(2) pairing Hamiltonian with
non-degenerate single particle orbits was introduced by
Richardson in the early sixties, although it was
recovered in the last decade in an effort to describe the
disappearance of superconductivity in ultrasmall grains.
Since then it has been widely applied to mesoscopic
systems where finite size effects play an important...
Dr
Jesper Levinsen
(University of Cambridge)
25/01/2013, 10:00
We investigate the three-body properties of two
identical "up" fermions and one distinguishable "down"
atom interacting in a strongly confined two-dimensional
geometry. We compute exactly the atom-dimer
scattering properties and the three-body recombination
rate as a function of collision energy and mass ratio
m_up/m_down. We find that the recombination rate for
fermions is...
Prof.
Nikolaj Zinner
(University of Århus)
25/01/2013, 10:30
The famous prediction of Efimov [1] that an infinitude of
three-body bound states appear in shortrange
interacting three-dimensional systems when there is a
two-body bound state at zero energy has
generated a large amount of interest in the cold atomic
gas community after its initial observation in
133Cs [2]. The theoretical description of these
experiments have thus far used the...
Prof.
Boris Malomed
(Tel Aviv University, Faculty of Engineering, Dept. of Physical Electronics)
25/01/2013, 14:00
The quantum-mechanical collapse (alias "fall onto the
center" of particles attracted by potential -1/r^2) is a well-
known issue in the elementary quantum theory. It is
closely related to the so-called "quantum anomaly", i.e.,
breaking of the scaling invariance of the respective
Hamiltonian by the quantization. We demonstrate that, in a
rarefied gas of quantum particles attracted by...
Prof.
Frederic Mila
(Ecole Polytechnique Federale de Lausanne)
28/01/2013, 10:00
In this talk, I will review the recent results we have
obtained on the SU(N) Heisenberg model of the Mott
insulating phase of multi-color ultracold fermionic atoms
loaded in optical lattices with various geometries. In 1D,
where Quantum Monte Carlo simulations can be performed, we
have calculated the correlations as a function of the
entropy per site, with the conclusion that the...
Prof.
Luis Santos
(Leibniz Universität Hannover)
28/01/2013, 14:00
Atoms in optical lattices present exciting possibilities of
control and quantum engineering. In this talk I would
like to discuss two different scenarios which may be
attained within the current state of the art. I will first
discuss the case of bosons in zig-zag optical
lattices [1], which may be created using superlattice
techniques. For the case of unconstrained bosons I will...
Prof.
Axel Griesmaier
(University of Stuttgardt, Germany)
29/01/2013, 10:00
In my talk I will try to to shine a light on the peculiar
stability conditions of dipolar Bose-Einstein
condensates trapped in 1D optical lattices. All effects
connected with the formation of ordered states in
dipolar quantum gases appear close to the border
between stability and instability of the trapped gas.
These features are mediated by the interplay between
short-range and...
Prof.
Cristiane Morais Smith
(Institute for Theoretical Physics, Utrecht)
29/01/2013, 14:00
During the last years, cold atoms loaded into optical lattices
emerged as an ideal playground to emulate condensed
matter systems. In this talk, I will first discuss a recently
proposed experimental set-up, which allows for the
realization of a spin-dependent optical lattice, in which an
effective Zeeman coupling can be generated by Raman
excitations [1]. The model Hamiltonian is...
Prof.
Jens Eisert
(Freie Universität Berlin)
30/01/2013, 11:00
Quantum simulators promise to simulate the dynamics of
complex quantum systems in a more efficient way than
what is classically possible. In this talk, we will elaborate on
the question in what sense experiments with ultra-cold
atoms in optical lattices can fulfil the promise of being first
dynamical quantum simulators truly outperforming classical
devices. We will discuss the...
Dr
Andre Eckardt
(MPIPKS Dresden)
30/01/2013, 14:00
In the last decade there has been considerable progress in
the experimental realization of artificial many-body systems
made of ultracold neutral atoms in optical lattices potentials.
These systems are extremely clean, well isolated from their
environment, and highly tunable (also during the
experiment). This makes them a flexible platform for
engineering many-body quantum physics...
Prof.
Giuliano Orso
(Université Paris Diderot)
31/01/2013, 10:00
We investigate the formation of bound states made of
two interacting atoms moving in a one dimensional
quasi-periodic optical lattice. We derive the quantum
phase diagram for Anderson localization of both
attractively and repulsively bound pairs. We calculate
the pair binding energy and show analytically that its
behavior as a function of the interaction strength
depends...
Prof.
Andreas Hemmerich
(Hamburg University)
31/01/2013, 14:00
Atoms trapped in optical lattices hold promises as a useful
new arena for studying many-body phenomena, possibly
providing helpful insights with regard to various
incompletely understood condensed matter scenarios.
Unfortunately, the shape that bosonic ground-state
wavefunctions can take is limited, apparently compromising
the usefulness of this approach for bosons. Such...
Dr
Pietro Massignan
(ICFO - Institute of Photonic Sciences)
01/02/2013, 10:00
A class of gapped many-body systems displays zero-
energy (Majorana) quasiparticles with non-Abelian
statistics and as a consequence possesses peculiar
topological phases [1, 2]. We discuss here how these
arise naturally in fermionic superfluids in 2D optical
lattices, in two different scenarios which may be soon
realized experimentally.
In first instance, we show how to create a...
Dr
Jan Budich
(Stockholm University)
01/02/2013, 10:30
Topological states of matter which can be understood
at the level of quadratic Hamiltonians have been in the
spotlight of condensed matter physics in recent years
and also the cold atoms community is currently
developing a major focus on this topic. In this talk, the
fundamental notion of topological states of matter is
reviewed in an accessible way. Furthermore, some very
recent...
Dr
Giovanni Mazzarella
(Università di Padova)
01/02/2013, 14:00
We consider ultracold and dilute bosonic atoms confined
by double-well shaped potentials. By employing the two-
site Bose-Hubbard (BH) model as a theoretical tool, we
describe the behaviour of such a system both at zero
and at finite temperature.
The ground-state of the two-site BH Hamiltonian will be
studied by analyzing how the inter-atomic interaction
affects the quantum...
Prof.
Gentaro Watanabe
(Asia Pacific Center for Theoretical Physics (APCTP))
01/02/2013, 14:30
Dissipation is typically considered to be a serious enemy to
quantum systems as it leads to a rapid decay of the
coherence. Surprisingly, however, recent studies show that
an appropriately designed coupling between the system and
the reservoir can drive the system into a given pure state
[1,2]. This opens the way for the use of dissipation in
quantum state engineering.
Here we...
Prof.
W. Vincent Liu
(University of Pittsburgh)
04/02/2013, 10:00
An exciting thrust of cold atom research is to explore some
unique aspects of such systems that have no prior
analogue in electronic solids. An emergent topic along this
line is the study of cold atoms coherently excited up to the
higher orbital bands of optical lattices in recent experiments,
motivated in part by early theoretical proposals. In this talk,
I will report in theory...
Prof.
Tilman Esslinger
(ETH, Zürich)
04/02/2013, 13:00
We report on the observation of short-range quantum magnetic
correlations of fermionic atoms in an optical lattice. The
key to entering the regime of quantum magnetism is a tunable
geometry optical lattice, which allows us to locally
redistribute the entropy. When loading a low-temperature
two-component gas with repulsive interactions into either a
dimerized or anisotropic simple cubic...
Prof.
Peter Zoller
(University of Insbruck)
04/02/2013, 15:00
Recently, the condensed matter and atomic physics
communities have mutually benefited from synergies emerging
from the quantum simulation of strongly correlated systems
using atomic setups. In the first part of the talk we give
an overview of analog and digital quantum simulation with
cold atoms in optical lattices and trapped ions. In the
second part we discuss possible future...
Dr
Teimuraz Vekua
(Leibniz University of Hannover)
04/02/2013, 16:50
We will discuss possibility of simulating exotic phases of
orbitally degenerate frustrated antiferomagnets in cold
gases. Two component Fermi gas loaded in the p-bands of the
zig-zag type optical lattice can mimic solid state
spin-orbital models such as transition-metal oxides with
partially filled d-levels, with the interesting advantage of
reviving the quantum nature of orbital...
Prof.
Gediminas Juzeliunas
(Vilnius University)
05/02/2013, 14:00
Over the last several years there has been a substantial
increase of interest in artificial gauge fields and
spin-orbit coupling for electrically neutral atoms [1–3].
The spin-orbit coupling with equal Rashba and
Dresselhaus contributions has been recently
implemented experimentally [4]. Here we consider
manifestations of such a spin-orbit coupling for
scattering of atoms at the...
Dr
Sukjin Yoon
(Asia Pacific Center for Theoretical Physics)
05/02/2013, 14:30
I will talk about an ongoing project on the non-equilibrium dynamics following
a quantum quench in a p-wave superfluid Fermi gas at zero temperature. P-
wave superfluid is known to undergo a quantum phase transition from a
gapless phase to a gapped phase when the p-wave interaction is tuned from
BCS to BEC regime. The dynamics of a polar state (possibly, axial
state in the near...
Mr
Prasanna Venkatesh
(McMaster University)
05/02/2013, 15:30
Quantum particles in a periodic potential subject to an
additional linear force undergo Bloch oscillation at a
frequency that is directly proportional to the magnitude
of the applied force. In this talk I will describe a novel in-
situ, non-destructive method to measure the Bloch
frequency for a cloud of cold atoms that are confined
within the electromagnetic field of a high quality...
Prof.
Jean Dalibard
(Collège de France et Ecole normale supérieure)
06/02/2013, 10:00
Among the large variety of quantum collective phenomena
that one hopes to address with atomic vapours, magnetism
is one of the richest. However the quest for the simulation
of magnetism immediately raises a challenging question:
how can a system of neutral atoms behave as an assembly
of charged particles in a magnetic field? The talk will review
some promising approaches to answer...
Prof.
Masahito Ueda
(University of Tokyo)
06/02/2013, 14:00
The second law of thermodynamics presupposes a clear-cut
distinction between the controllable and uncontrollable degrees of
freedom by means of macroscopic operations. The cutting-edge
technologies in quantum information and nanoscience seem to require us
to abondon such a working hypothesis in favor of the distinction between
the accessible and inaccessible degrees of freedom. In this...
Dr
Öhberg Patrik
(Heriot-Watt University)
06/02/2013, 15:30
We show how density dependent gauge potentials can be
induced in dilute gases of ultracold atoms using
light-matter interactions. We study the effect of the
resulting interacting gauge theory and show how it gives
rise to novel topological states in the ultracold gas. We
find in particular that the onset of persistent currents in
a ring geometry is governed by a critical number...
Prof.
Qi Zhou
(The Chinese University of Hong Kong)
07/02/2013, 10:00
The recent realization of synthetic gauge fields for ultra
cold atoms provides physicists exciting opportunities to
investigate the interplay between two fundamental phenomena
in nature, Bose-Einstein condensation and spin-orbit
coupling. In this talk, I will discuss a novel effect of
spin-orbit coupling in bosonic systems, namely, it can
destroy a high-dimensional condensate even at...
Dr
Marcello Dalmonte
(Insbruck)
07/02/2013, 10:30
Motivated by ground-breaking experimental findings,
static gauge potentials and topological phases of
matter are currently two of the most intriguing topics in
cold atom physics. In the first part of the talk, we will
show how topological phases supporting Majorana
edge states emerge in simple toy models of fermionic
ladders without the need of any additional reservoir by...
Prof.
Alexander Altland
(Köln Universität)
08/02/2013, 10:00
We will discuss mechanisms of effective equilibration
('thermalization') for unitary quantum dynamics under
conditions of classical chaos. Focusing on the paradigmatic
example of the Dicke model, we will explore how a
constructive description of the thermalization process is
facilitated by the Glauber Q or Husimi function, for which
the evolution equation turns out to be of...
Dr
Clement Wong
(Utrecht University)
08/02/2013, 15:30
We study the Hall conductivity in a spin-orbit coupled
bosonic Mott insulator. Using a strong-coupling
perturbation theory, we show that in the spinful Bose
Hubbard model, interactions can induce momentum-space Berry
curvature, leading to the anomalous Hall phase.
Furthermore, we find that the ground state can in principle
support an integer Hall conductivity, i.e., the...
Prof.
Wilhelm Zwerger
(Technische Universität München)
11/02/2013, 10:00
Dr
Brandon Anderson
(Joint Quantum Institute)
11/02/2013, 15:30
Isotropic spin-orbit couplings, such as Rashba in two
dimensions, have a continuous symmetry that produces a large
degeneracy in the momentum-space dispersion. This degeneracy
leads to an enhanced density-of-states, producing novel
phases in systems of bosonic atoms. This model is
idealistic, however, in that the symmetry of the lasers will
weakly break the continuous symmetry to a...
Dr
Konstantin Krutitsky
(Universität Duisburg-Essen)
11/02/2013, 16:00
We have studied the phase diagram of a quasi-two-dimensional
interacting Bose gas at zero temperature in the presence of
random potential created by laser speckles. The superfluid
fraction and the fraction of particles with zero momentum
are obtained within the mean-field Gross-Pitaevskii theory
and in diffusion Monte Carlo simulations. We find a smooth
crossover from the superfluid to...
Dr
Shaoyu Yin
(Department of Applied Physics, Aalto University)
12/02/2013, 10:00
The temperature dependence of the thermodynamic potential of quantum
chromodynamics (QCD), the specific heat, and the quark effective mass are calculated for
imbalanced quark matter in the limit of a large number of quark flavors (large-NF), which
corresponds to the random-phase approximation. Also a generalization of the relativistic
Landau effective-mass relation in the imbalanced...
Dr
Elife Karabulut
(Lund University)
12/02/2013, 10:30
The high degree of tunability and flexible control are the
two important features associated with cold atomic gases,
which have so far paved the way for various applications
including ow-dimensional systems, confining potentials with
different functional forms, multi-component Bose-Einstein
condensates (BECs), quantum gases with different inter-particle
interactions, etc. Systems...
Prof.
Stephanie M Reimann
(Lund University)
12/02/2013, 14:00
Cold atom systems offer many possibilities to shape
mesoscopic quantum systems with properties that are
fundamentally different from semiconductor
nanostructures, such as quantum dots and quantum
wires with electrons. The talk will provide a review on
the many-body physics of these finite-size bosonic or
fermionic quantum systems, with focus on the
configuration interaction...
Dr
Omjyoti Dutta
(ICFO - The Institute of Photonic Science)
12/02/2013, 16:00
A natural description of ultracold gases trapped in optical
lattices is given by the so-called single-band Hubbard
model. We will discuss the additional effects of interaction
to induce intra- as well as inter-band scattering to
neighbouring sites, which shows up as density dependent
correlated tunneling processes. Such processes can
spontaneously give rise to various exotic phases....
Prof.
Päivi Törmä
(Aalto University)
13/02/2013, 14:00
We propose a mixed-geometry system of fermionic
species selectively confined in lattices of different
geometry [1]. We investigate how such asymmetry can
lead to exotic multiband fermion pairing in an example
system of honeycomb and triangular lattices. A rich
phase diagram of interband pairing with gapped and
gapless excitations is found at zero temperature. We
find that the...
Dr
Reza Bakhtiari
(Institut für Theoretische Physik Hamburg)
13/02/2013, 15:30
We theoretically investigate the thermodynamics of an
interacting inhomogeneous two-component Fermi gas in an
optical lattice. Motivated by a recent experiment, Science,
327, 1621 (2010), we study the effect of the interplay
between thermodynamics and strong correlations on the size
of the fermionic cloud. We use dynamical mean-field theory
to compute the cloud size, which in the...
Prof.
Maciej Lewenstein
(ICFO, Barcelona)
14/02/2013, 10:00
I will present an introduction to the theory of quantum
link models, a.k.a. gauge magnets, that are particularly
suitable for realizations with ultracold atoms. These
models provide an alternative to the standard Wilson's
method formulation of lattice gauge theories (LGT).
I will derive the simplest Hamiltonian for Abelian U(1)
LGT and show the simplest SU(2) extension....
Dr
Daniel Cocks
(Goethe University Frankfurt)
14/02/2013, 14:00
We investigate effects of interactions and trapping in a
cold-gas realization of a 2D time-reversal invariant
topological insulator. In contrast to solid-state systems,
the effects of trapping and the relatively small scale of
cold-gas systems can significantly effect the edge states of
topological systems. By choosing explicit realizations of
the Hofstadter lattice with various...
Prof.
Uwe Fischer
(Seoul National University)
14/02/2013, 14:30
We argue that forcing an interacting quantum many-body
system to reside after a quench far from its equilibrium
state, is an important tool to reveal information on the
correlations in the initial ground state. We discuss two
examples in detail:
[1] We investigate the collapse and revival of first-order
coherence in deep optical lattices when long-range
interactions are turned on and...
Dr
Stefan Baur
(University of Cambridge)
14/02/2013, 15:30
Ultracold atoms in Raman-dressed optical lattices allow for
effective momentum-dependent interactions among
single-species fermions originating from short-range s-wave
interactions. These dressed-state interactions combined with
very flat bands encountered in the recently introduced
optical flux lattices push the Stoner instability towards
weaker repulsive interactions, making it...
Dr
Matthew Edmonds
(Heriot-Watt University)
14/02/2013, 16:00
Over the last two decades ultracold atomic gases have formed
the basis for a plethora of theoretical and experimental
investigations of matter at the nano Kelvin temperature
regime. Condensates formed from either bosonic or fermionic
matter offer a large degree of experimental control, and as
such it is now possible to perform quantum simulations of
various physical scenarios envisaged...
Dr
Bruno Julia-Diaz
(ICFO - The Institute of Photonic Sciences)
15/02/2013, 14:00
We employ the exact diagonalization method to analyze the
possibility of generating strongly correlated states in
two-dimensional clouds of ultracold bosonic atoms which are
subjected to a geometric gauge field created by coupling two
internal atomic states to a laser beam. Tuning the gauge
field strength, the system undergoes stepwise transitions
between different ground states, which...
Mr
Tobias Grass
(ICFO - The Institute of Photonic Science)
15/02/2013, 14:30
Artificial gauge fields for cold atoms are tools for
producing topological quantum states. In spinless or
spin-polarized systems, cold bosons are known to support the
incompressible phases from the Read-Rezayi series,
containing also the famous Laughlin and Moore-Read states
with anyonic or even non-Abelian quasiparticle excitations.
Here we show that in the case of a pseudospin-1/2 Bose...
Dr
Omjyoti Dutta
(Institute of Photonic Sciences)
A natural description of ultracold gases trapped in optical
lattices is given by the so-called single-band Hubbard
model. We will discuss the additional effects of interaction
to induce intra- as well as inter-band scattering to
neighbouring sites, which shows up as density dependent
correlated tunneling processes. Such processes can
spontaneously give rise to various exotic phases....
Prof.
Qi Zhou
(The Chinese University of Hong Kong)
The recent realization of synthetic gauge fields for ultra
cold atoms provides physicists exciting opportunities to
investigate the interplay between two fundamental phenomena
in nature, Bose-Einstein condensation and spin-orbit
coupling. In this talk, I will discuss a novel effect of
spin-orbit coupling in bosonic systems, namely, it can
destroy a high-dimensional condensate even at...
