Name: Quantum Solids, Liquids, and Gases
Start: 2010-07-19T08:00:00+02:00
End: 2010-08-27T18:00:00+02:00
Location: Nordita

Monday, 19 July 2010

09:15

09:15 - 14:00

14:00 Coffee break
Coffee break
14:00 - 14:15
14:15 From ultracold atoms to realization of strongly correlated condensed matter models - Paata Kakashivili (NORDITA)
From ultracold atoms to realization of strongly correlated condensed matter models
- Paata Kakashivili (NORDITA)
14:15 - 15:15
Progress in ultracold atomic physics allows to engineer and probe analogs of condensed matter systems. Using Feshbach resonance and optical lattices experimentalist are able to realize regimes where interactions between atoms play a crucial role. I will describe how dimensional reduction, in particular to 1D, is achieved by turning on an optical lattice and how interactions can be tuned using Feshbach resonance. For fermonic atoms and repulsive interactions, regimes such as the spin-coherent Luttinger liquid and the spin-incoherent Luttinger liquid can be realized by tuning the inter-atomic interaction strength and trap parameters. On the other hand, for attractive interactions, we study pairing in a spin-imbalanced ultracold atomic system of fermions to identify exotic states such as the 1D analog of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state. In addition, I will also describe possibilities to study interplay between interaction and disorder in ultracold atomic systems. In particular, we investigate the damped hydrodynamic transport of a trapped Bose-Einstein condensate of bosonic atoms through a disordered potential created by an optical-speckle. Finally, I will summarize and address the concrete prospects for realizing and probing these phenomena experimentally using Feshbach resonances, optical lattices and optical speckles.
Tuesday, 20 July 2010

10:40 Coffee break
Coffee break
10:40 - 11:00
11:00 Discrete reduced-symmetry solitons and second-band vortices in two-dimensional nonlinear waveguide arrays - Magnus Johansson (Linköping University)
Discrete reduced-symmetry solitons and second-band vortices in two-dimensional nonlinear waveguide arrays
- Magnus Johansson (Linköping University)
11:00 - 12:00
Considering a two-dimensional lattice of weakly coupled waveguides,where each waveguide may carry two orthogonal modes of dipolar character, we present a nonlinear discrete vector model for the study of Kerr optical solitons with profiles having a reduced symmetry relative to the underlying lattice. We describe analytically and numerically existence and stability properties of such states in square and triangular lattices and also reveal directional mobility properties of two-dimensional gap solitons which were recently observed in experiment. The model also describes one-site peaked discrete vortices corresponding to experimentally observed second-band vortex lattice solitons, for which oscillatory instabilities are predicted. We also introduce a concept of rotational Peierls-Nabarro barrier characterizing the minimum energy needed for rotation of stable dipole modes and compare numerically translational and rotational energy barriers in regimes of good mobility. A similar model has also recently been proposed as a mean-field model for p-band bosons in optical lattices, describing quantum states in the superfluid regime.
14:00 Coffee break
Coffee break
14:00 - 14:15
14:15 Superfluidity in Quantum Hall Bilayers - Herbert Fertig (Indiana University)
Superfluidity in Quantum Hall Bilayers
- Herbert Fertig (Indiana University)
14:15 - 15:15
In this talk I will review some of the ideas and experiments suggesting that quantum Hall bilayers near filling factor 1 may form an exciton condensate state, leading to the possibility of superflow for counterflowing currents in the two layers. In real experiments, dissipationless transport appears to emerge, it at all, only at zero temperature, so that the observed superfluidity is at best imperfect. This appears likely to be due to disorder, which can flood the system with merons -- vortex-like excitations -- even at zero temperature. I will discuss a "coherence network" model which incorporates the presence of these objects in the groundstate, and qualitatively captures much of the physics observed in experiment. Finally I will discuss the results of drag experiments in this system, where interlayer coherence and quantum Hall physics conspire in such a way that one can probe different types of merons with measurements on different layers.
Wednesday, 21 July 2010

10:40 Coffee break
Coffee break
10:40 - 11:00
11:00 Topological creation of vortices and monopoles in spin-1 Bose-Einstein condensates - Mikko Möttönen (Aalto University)
Topological creation of vortices and monopoles in spin-1 Bose-Einstein condensates
- Mikko Möttönen (Aalto University)
11:00 - 12:00
I will give a review of the theoretical and experimental studies on the so-called topological vortex formation, in which a vortex-free spin-1 BEC is manipulated adiabatically using external magnetic fields into a state which contains a multiply quantized vortex. Even vortex pumping can be obtained to create deterministically vortices with high quantum numbers. Very recently, we extended this idea for a non-trivial three-dimensional case, in which Dirac monopoles can be created. This observation takes BEC to have high potential for the first experimental observation of Dirac monopoles, analogs of magnetic monopoles, in any quantum field.
14:00 Coffee break
Coffee break
14:00 - 14:15
14:15 Polarized atomic Fermi gases in optical lattices with elongated traps : a real-space dynamical mean-field theory - Dong-Hee Kim (Aalto University)
Polarized atomic Fermi gases in optical lattices with elongated traps : a real-space dynamical mean-field theory
- Dong-Hee Kim (Aalto University)
14:15 - 15:15
We study fermionic superfluidity of ultracold atom gases in optical lattices with elongated traps using the real-space dynamical mean-field theory (DMFT). First, the overview of DMFT and some details of our implementation of its real-space version will be given in the talk. Second, we will outline our recent progress in understanding the competition between the superfluidity and the spin polarization using our real-space DMFT code. We will discuss about the existence of critical polarization, the possibility of an exotic superfluid phase and the effect of the anisotropy of trapping potentials in three and two dimensional systems.
Thursday, 22 July 2010

10:40 Coffee break
Coffee break
10:40 - 11:00
11:00 Magnetic Richtmyer-Meshkov instability in a two-component Bose-Einstein condensate - Alice Bezett (Umeå University)
Magnetic Richtmyer-Meshkov instability in a two-component Bose-Einstein condensate
- Alice Bezett (Umeå University)
11:00 - 12:00
The magnetically induced Richtmyer-Meshkov instability in a two-component Bose-Einstein condensate is investigated. We construct and study analytical models describing the development of the instability at both the linear and nonlinear stages. The models indicate new features of the instability: the influence of quantum capillary waves and the separation of droplets, which are qualitatively different from the classical case. We perform numerical simulations of the instability in a trapped Bose-Einstein condensate using the Gross-Pitaevskii equation and compare the simulation results to the model predictions.
14:00 Coffee break
Coffee break
14:00 - 14:15
14:15 p-orbital ultracold particles and Bose-Einstein crystal - Vincent Liu (University of Pittsburgh)
p-orbital ultracold particles and Bose-Einstein crystal
- Vincent Liu (University of Pittsburgh)
14:15 - 15:15
The p-orbital band of optical lattices is a topic that emerged in recent few years of theoretical studies. Experimental observations of p-band BEC (reported by T. Mueller et al 2007 and G. Wirth et al 2010) make this topic an exciting one. In this talk, I will first try to explain why the system of ultracold particles in the lattice p-bands is conceptually intriguing and unique to cold atomic gases. Then I will report some interesting new quantum orbital phases that we have found, such as finite-momentum px+ipy Bose-Einstein condensates, staggered orbital currents, stripes of angular momenta, and incommensurate super-current density wave, as well as the realization of some condensed matter orbital models such as the quantum 120 degree model and the quantum dimer model. Work done in collaboration with X. Li, C. Lin, J. Moore, S. Das Sarma, K. Sun, V. M. Stojanovic,C. Wu, and E. Zhao.
16:00

16:00 - 19:00
Friday, 23 July 2010

10:40 Coffee break
Coffee break
10:40 - 11:00
11:00 Vortex Dynamics and Hall Conductivity of Hard Core Bosons - Assa Auerbach (Technion (Haifa))
Vortex Dynamics and Hall Conductivity of Hard Core Bosons
- Assa Auerbach (Technion (Haifa))
11:00 - 12:00
13:30 Coffee break
Coffee break
13:30 - 13:45
13:45 Recent Theory on FFLO and pair density wave superconductivity - Daniel Agterberg (University of Wisconsin - Milwaukee)
Recent Theory on FFLO and pair density wave superconductivity
- Daniel Agterberg (University of Wisconsin - Milwaukee)
13:45 - 14:45
With the groundbreaking work of Fulde, Ferrell, Larkin and Ovchinnikov (FFLO), it was realized that superconducting/superfluid order can also break translational invariance, leading to a phase in which the Cooper pairs develop a coherent periodic spatially oscillating structure. Such pair density wave (PDW) superconductivity/superfluidity has become relevant in a diverse range of systems, including cuprates, organic superconductors, heavy-fermion superconductors, cold atoms, and high-density quark matter. In this talk I discuss recent theoretical developments on PDW/FFLO phases. This will include both a discussion of the microscopic origin of such phases in materials lacking parity symmetry and a phenomenological description of these phases highlighting the role of fractional vortices and dislocations.
Saturday, 24 July 2010
Sunday, 25 July 2010