Exotic Quantum Phases Group


cold atoms
Cold atoms

Recent advances in experimental control of old atomic systems allow one to realize strongly correlated bosonic and fermionic states experimentally, establish novel phases of matter, study topological excitations, or investigate prospects of quantum computations.

One of the main goals of our group is to identify and study theoretically exotic phases appearing in cold atomic systems such as, e.g., the  "baryonic" state [Phys. Rev. Lett. 98, 160405] or the color superfluid state emerging in multicomponent fermionic systems, or novel quantum glass phases appearing in Bose-Fermi mixtures [Phys. Rev. Lett. 105, 115301]. We also study topological excitations in these systems, such as, e.g., Skyrmions in strongly interacting multi-component systems, or vortices in nematic phases.

Our other main line of our research focuses on dynamical aspects of cold atomic systems; we investigate non-equilibrium phenomena such as out of equilibrium relaxation, post-quantum quench dynamics [Phys. Rev. Lett. 106, 156406] or work statistics.   


Quantum interference effects and correlation effects distinguish quantum transport through nanostructures through quantum dots and nano-wires from more conventional transport.

We study transport and dynamical correlations in correlated quantum systems under out of equilibrium conditions using numerical and analytical field theoretical methods such as functional or numerical renormalization group techniques. We investigate, e.g. transport through coupled double dot systems [Phys. Rev. Lett. 90, 026602], and sudy the emerging non-Fermi liquid states in these devices.  We also study the (quantum) noise spectrum of correlated quantum dots [Phys. Rev. Lett. 108, 046802 (2012)],  and investigate the dynamics of cavity-coupled quantum dots.

Low dimensional

One of the most interesting effect in 2D electron systems is the quantum Hall effect (QHE), a microscopic quantum state of electrons in strong magnetic fields, that shows topological order. The integer QHE is a one-particle effect, whereas the fractional QHE is a manifestation of the strong correlation between electrons. The physics of the lowest Landau-level in the Quantum-Hall regime is well described by the so called composite fermion model. However, on higher levels, or in multilayer systems, the explanation of many effects is an open question.

We investigate the fractional QHE states on higher Landau-levels, particularly the formation of non-Abelian states. We are also interested in anisotropic, multicomponent  and spin-orbit coupled systems, and the QHE in graphene and other recently discovered materials.