Jan 15 – 16, 2009
Niels Bohr International Academy
Europe/Copenhagen timezone

Participants' interests

ANDERSEN, Jens Oluf (Trondheim)

Research interest: Bose-Einstein condensation in general (pions, kaons, and cold atoms) BEC-BCS crossover in quark matter.
Goal: Get a flavor of what is going on in the field.


APAJA, Vesa (Oulu)

Simulation of 1D fermion lattices using matrix product state description,
so far application to radio frequency response of 3-state systems.
Monte Carlo simulation of 3D Bose lattices. Special interest
on development of fermion simulation algorithms, PEPS etc.

ARMSTRONG, Jeremy (Lund)

I am currently working on pairing in 2D atomic traps. I have done work with small particle systems so far (up to 9 particles), and am currently working on expanding to larger particle numbers to see what size of problems are tractable with the theory.

BARGI, Sara (Lund)

Research interests and work so far: cold atom gases, in particular Bose-Einstein condensates, in particular under rotation.


BLOCH, Immanuel (Mainz)

"Strongly correlated Bosons, Fermions and Bose-Fermi mixtures in optical lattices"

Ultracold quantum gases in optical lattices allow one to explore the
fundamental behaviour of strongly correlated many-body quantum systems
with different quantum statistics. We show that by using novel probes,
one can measure static and dynamical properties of these systems. For
example the compressibility of a fermionic quantum gas mixture with
repulsive interactions can be measured by probing the size of the
system as an external confinement is increased. Thereby metallic and
insulating phases can be distinguished from each other in a direct way.
Our results are compared to ab-initio calculations of the Hubbard model
using Dynamical Mean Field Theory (DMFT) and provide a first ab-initio
test of DMFT. For attractive interactions between the fermions in the
lattice, we find a peculiar anomalous expansion of the Fermi gas with
increasing attractive interaction strength. This is attributed to the
crossover of the gas from weakly bound pairs to hardcore bosons and a
coinciding loss of the spin degrees of freedom of the system.
Furthermore we show, how quantum phase diffusion can be used to
precisely determine the renormalized interaction and tunneling
parameters of interacting Bose-Fermi mixtures in optical lattices. This
has allowed us to identify in parts the mechanism underlying the strong
shift of the superfluid to Mott insulator transition when fermions
with attractive interactions are added to a bosonic superfluid. Finally we show how
spin-spin superexchange interactions can be controlled in optical superlattices
and used for the efficient and massively parallel creation of entangled
Bell pairs in the lattice.


BRUUN, Georg (Copenhagen)

RF spectroscopy -Dipoles -Optical Lattices -Collective Modes and Viscosity.

CETOLI, Alberto (Umeå)

So far I have been working on solitons in bosonic superfluids, dynamics of atoms in optical lattices, and quantum phase transitions in optical lattices. Currently I am working on vortices in fermionic superfluids and cold atoms in disordered potentials. I would like to study more in detail the behavior of fermions at the unitary limit.

CHALLIS, Katherine (Aarhus)

My main research interest is the theoretical description of degenerate Fermi gas dynamics. Recently I have been investigating methods for probing pair correlations in these systems, e.g., Bragg scattering and elastic single-particle scattering. In the future, we are interested in diffraction, localization phenomena, and Josephson junctions. This workshop is a good opportunity to meet some of the researchers associated with the Nordforsk Network and to learn about the quantum gas research being done in this community.

CHRISTENSSON, Jonas (Lund)

Interests: General theoretical many- (or few-)body physics. Current research involves strongly correlated electrons in quantum dots and cold atom gases, rotation and vortices in such systems, exciton-condensation, and also development of computational methods. A current research problem: In a system with two kinds of fermions with attractive interactions (say, electrons and holes, or spin up and down atoms), composite bosonic particles may form. How do one know if these bosons have formed a condensate? Given the full fermionic wavefunction of the system, is there any criterion for condensation one may use? Future direction: Don't know yet...

COLLIN, Anssi (Stockholm)

Ultracold atomic gases at nonzero temperatures, in particular double wells and Josephson oscillations. Other interests: multiband bosons in optical lattices, rotating ultracold gases.

DEURETZBACHER, Frank (Lund)

Strongly correlated one-dimensional bosons, Fermi-Bose mapping, spin dynamics of spinor Bose-Einstein condensates

FEDOROV, Dmitri (Aarhus)

FOGEDBY, Hans (Aarhus)

Quantum many body statistical physics, soft condensed matter, biophysics.

FORSSEN, Christian (Gothenburg)

Few-body systems, ab initio theory of nuclei and other strongly interacting particles. Effective interactions and exact diagonalization.

GADSBØLLE, Anne-Louise (Aarhus)

Quantum gases. Calculations of energy shifts due to a phase twist for fermions in an optical lattice. Calculations beyond the nearest neighbor approximation are being performed.

GAMMELMARK, Søren (Aarhus)

I'm studying the effects of measurements on various physical systems, in particular quantum gases, with the intention of inducing dynamics by using feedback-methods.

JENSEN, Aksel (Aarhus)

Few-body problems in nuclei, molecules and atoms. I come to listen, get updated and discuss with the other participants.

JOHANSSON, Markus (Linkoping)

My main research interests concern fundamental phenomena in the nonlinear dynamics of anharmonic lattices, such as localization, transport, instabilities and thermodynamics, and the possibility (?) of their experimental observation for BEC's in optical lattices. Particularly interested in quasiperiodic and random systems, and the interplay between nonlinearity and aperiodicity which experimentally may be observed for BEC's in quasiperiodic or random potentials.

KAMPEL, Nir (Copenhagen)

Light-matter interaction in ultra-cold gases, quantum memory and BEC decoherences.

KAVOULAKIS, Georgios (Heraklion)

Physics of cold atoms, nonlinear effects, superfluidity, transport properties, collective effects, excitons in semiconductors, mathematical modelling

KJÆRGAARD, Niels (Copenhagen)

Quantum state engineering; Light-matter interaction.

KOCHBACH, Ladislav (Bergen)

My own work is on very diverse parts of atomic theory and quantum physics. The purpose of my participation is to present the recent work of our group in Bergen. Also, I will naturally try to bring back home the experience from the meeting to share with my colleagues.

KRISTINSDOTTIR, Liney Halla (Lund)

In my masters project I will consider two quantum dots, each with a few fermions of opposite charge, and consider the fermions' behaviour as the distance between the quantum dots is changed. My primary aim in attending the workshop is to get to know its subject better, i.e. listen and learn.

LARSON, Jonas (Stockholm)

Interests, ongoing and future projects include. 1) Multi-component atoms in optical lattices - interplay between external and internal atomic degrees of freedom. 2) Multi-band physics of atoms in optical lattices - effects of higher bands. 3) Ultracold atoms in optical lattices formed inside cavities - strong non-linear effects. 4) Coupled spinor BECs - geometric phases, entanglement, effective gauge fields... 5) Cavity QED - The Jaynes-Cummings model and its extensions. 6) Using cavity QED to simulate other simple systems. 7) Cavity QED - Coupling of a BEC to a quantized cavity mode. 8) Dynamics of simple molecular systems. 9) Dynamics of ion-traps.

LE TARGAT, Rodolphe (Copenhagen)

BEC experiment at Quantop, study of superradiance, implementation of a quantum memory protocol in a BEC.

MANNINEN, Matti (Jyvaskyla)

Rotational states in confined quantum system: particle localization, vortices, and relation between boson and fermion systems.

MOTTELSON, Ben (Copenhagen)

Distribution of angular momentum in cold gases

MØLMER, Klaus (Aarhus)

We are working on fermions in lattices, scattering on fermions, fermions as "quantum simulators" of superconducting systems.

MUELLER, Jörg Helge (Copenhagen)

Light-matter interaction in ultra-cold gases, quantum state transfer between different systems and engineering of states.
 
 NYGAARD, Nicolai (Aarhus)
 
 Superfluidity and quantized vortices. Feshbach resonances and molecule formation. Dynamics of quantum gases with tunable interactions. Non-equilibrium many-body dynamics and kinetic theory. Atomic gases in optical lattices. Numerical methods. Scattering theory.     
 
 PETHICK, Chris (Copenhagen)
 
 Strongly interacting Fermi systems and especially frequency shifts due to interactions. A second interest is spin correlations in systems with noncentral interactions, particularly in nuclear matter. Another question I am interested in is why most deformed nuclei are prolate. I have yet to see a convincing explanation. At the workshop I foresee at least two possible fruitful points of contact with other members of the network. On spin correlations, A. Shelankov and J. Rammer (Umeå) have experience with nonequilibrium processes that could be valuable. On nuclear deformations, it would be useful to share experience with people from Lund (Jeremy Armstrong, Ikuko Hamamoto).
 
POLZIK, Eugene (Copenhagen)

Quantum interface between atoms and light. Probing and engineering entangled
quantum states of atomic systems. Possible topic of interaction with
participants: quantum interface between ultracold atoms and photons.

RAMMER, Jørgen (Umeå)

I have a broad interest in statistical physics, and are presently interested in applying counting statistics methods to problems in quantum optics. I look forward to the talks, and to hear also about current interests in atomic Fermi gases, and to explore if some of the well-known techniques from solid state physics can find useful applications in this area.
 
REIMANN, Stephanie (Lund)

Finite fermion and bosons systems, such as quantum dots and other semiconductor nanostructures, or atoms in traps. Many-body methods for the description of correlated quantum systems. Vortices in quantum liquids, both with BEC, but also analogies to quantum dots at strong magnetic fields. More recently my interest turned to questions of quantum transport in atomic quantum gases and "atomtronics", interaction blockade and "quantum dots with atoms".
 
SAARIKOSKI, Henri (Lund)

At the moment I'm working with finite-size 2D rotating quantum systems such as quantum dots and cold-atom condensates. In future I would focus also on spin processes in 1D quantum wires.

SCHIROTZEK, Andre (MIT)

 "Experiments on strongly interacting ultracold Fermi gases"

 Recently, our focus has been on systems with density imbalance. These systems exhibit a rich phase diagram across the BEC-BCS crossover allowing access to physically very different regimes. So far, our studies have focused on density distributions and response to radio-frequency excitation. In the future we plan to extend our tool set to collective excitations, Bragg scattering and Raman scattering.

SCHLAGHECK, Peter (Lund and Regensburg)

I am interested in transport processes of ultracold quantum gases and their relation to mesoscopic transport physics with electrons. Key topics to be addressed in this context include interaction blockade phenomena in atomic quantum dots, Kondo physics with cold atoms, as well as Anderson localization in disorder potentials, to mention some examples. Up to now, we mainly focused on transport processes with Bose-Einstein condensates in the mean-field regime. In the near future, I plan to extend our studies to strongly interacting Bose gases as well as to ultracold fermionic gases.

SENGSTOCK, Klaus (Hamburg)

Quantum gases, quantum gas mixtures, bosonic and fermionic quantum gases, quantum gases in optical lattices, spinor BEC, linear and nonlinear atom optics, light matter interaction, quantum interfaces, laser development, ultrahigh precision spectroscopy.

SHELANKOV, Andrey (Umeå)

BACKGROUND: Solid state theory (superconductivity, especially), quantum transport, quantum dissipative systems (master equation, counting statistics, quantum noise, etc). Since year 2000, teaching "Quantum Information" (master Umeå level). CURRENT RESEARCH: Josephson-like physics of BEC's, statistics of interference image of expanding BEC clouds. AIM in PARTICIPATING: Besides learning something new, the aim is to find out the possibilities for collaboration with other groups, especially experimental, that study quantum macroscopic system (boson or fermion cold atoms) and/or quantum optics in relation (in a broad sense) to quantum information.

SMITH, Henrik (Copenhagen)

Having (barely) recovered from publishing the second edition of "Bose-Einstein Condensation in Dilute Gases" together with C.J. Pethick (Cambridge University Press, 2008) I keep an interest in phenomena at the crossover between Bose-Einstein condensation and Bardeen-Cooper-Schrieffer superfluidity. At the moment I would like to derive a kinetic equation in the unitarity limit, using the Keldysh technique, within a high-temperature expansion, in order to obtain corrections to the classical limit in which the frequency and attenuation of collective modes can be calculated very accurately. I am also interested in understanding the relationship (at non-zero temperature) between Bose-Einstein condensation in atomic gases and in magnetic insulators such as TlCuCl_3 and BaCuSi_2O_6.

SUOMINEN, Kalle-Antti (Turku)
 
 We currently work on a couple of topics: - spinor interferometers - non-Markovian dynamics and decoherence of quantum states In the latter case we concentrate on a) the methodology (quantum jump methods, time-local master equations, pseudomodes) and b) implementation (ESD - entanglement sudden death, entanglement protection).
 
SØE SØRENSEN, Ole (Aarhus)
 
Deformations of vortex structures in BECs (twisting), atom-molecule mixtures in optical lattices, Feshbach resonances.
 
SØRENSEN, Anders (Copenhagen)

Theoretical quantum optics, in particular quantum information but also ultra cold atoms. My main interest so far has been to come up with theoretical ideas for interesting experiments which could be performed.

THØGERSEN, Martin (Aarhus)

Universal Efimov physics in cold bosonic gases and few-body systems. Finite range corrections to Efimov physics, beyond the scattering length approximation. Quantitative connections between Efimov physics and Borromean binding. Existence of many-body Efimov effects? Common methods: Adiabatic Hyperspherical Approximation. Stochastic Variational Method. Modelling of Feshbach resonances with finite range potentials.

TORMA, Paivi (Otaniemi)

Theory of ultracold Fermi gases; superfluidity, strong correlations, quantum dynamics.

VIEFERS, Susanne (Oslo)
 
 My main field of research is the quantum Hall effect, which some years ago led me to a particular interest in the theoretically predicted quantum Hall-like states in rapidly rotating ultracold atomic gases. At present, I mainly work on the conformal field theory description of the quantum Hall effect. However, an interesting problem I would like to learn more about from people at this workshop and start looking into, is how to understand the (vortex melting) transition from an Abrikosov vortex lattice to the homogeneous quantum Hall-type states in a rapidly rotating BEC. Also, I am interested in ideas on how to actually realize such QH states experimentally, e.g. using optical lattices.

WOLF, Michael (Copenhagen)

Interests: Quantum Many-Body theory on lattices, Quantum Information Theory Aims: get to know the experimental state-of-the-art.

WUBS, Martijn (Copenhagen)

Theoretical quantum optics, light-matter interfaces, continuous-variable quantum communication, (adiabatic) quantum computation, circuit QED.

YU, Zhenhua (Copenhagen)

I'm interested in the rf spectrum of strongly interacting fermion gases. I'm trying to understand the mean field energy in unitary fermion gases revealed recently at MIT. I'm also working on the problem using photoassociation as a probe of the correlation at short distances in cold atoms.

ÖGREN, Magnus (Lund)

Shell structure Quantum dynamics of cold gases (ONLY PRESENT ON FRIDAY)

ÅBERG, Sven (Lund)

Pairing in finite-size systems. Semiclassical description of BCS, Role of order-chaos, Shell structure.