Many-Body Localisation of Fermions in a 1D Quasi-Random Disordered Lattice (M. Schreiber) / Photon Transmissions in Rydberg-EIT Systems by Multi-Photon Scattering Theory (Dr. T. Shi)
- Double Feature!
- Date: Jul 14, 2015
- Time: 02:30 PM - 04:00 PM (Local Time Germany)
- Speaker: Dipl. Phys. Michael Schreiber, Abt. Quanten-Vielteilchensysteme / Dr. Tao Shi, Abt. Theorie
- Room: Herbert Walther Lecture Hall
- Host: MPQ
Many-Body Localisation of Fermions in a 1D Quasi-Random Disordered
Lattice (M. Schreiber)
While Anderson localisation of non-interacting particles has been
studied extensively, much less is known about localisation in
interacting systems. As an experimental probe, we study in an
interacting many-body system the breakdown of ergodicity and the
resulting absence of thermalisation, which are some of the key features
of localised systems. We have investigated the many-body localization
transition for interacting ultracold fermions in a quasi-random 1D
lattice by measuring the relaxation dynamics of an initial Charge
Density Wave (CDW). While the CDW order quickly decays in the
thermalising case, a CDW order persisting for long evolution times,
reveals the breakdown of ergodicity and many-body localisation. We have
characterised this phase transition and studied the influence of energy
density on localisation.
Photon Transmissions in Rydberg-EIT Systems by
Multi-Photon Scattering Theory (Dr. T. Shi)
We develop the scattering theory to study
the multi-photon transport to the quantum emitters by using the quantum
regression theorem and the path integral formalism. The transition
amplitude, the S-matrix, and the generalized master equation for the
emitters during the scattering processes are investigated. Here, the
path integral formalism results in the exact result, which can be used
to check the validity of the Born-Markov approximation used in the
quantum regression theorem. By using two examples, i.e., few-photon
scattering by the two-level system and the Jaynes-Cummings model, we
show that how to apply the scattering theory to study the quantum
statistics of the out-going photons and the transient processes of the
emitters. Finally, we apply the developed scattering theory to study the
few-photon transport to the Rydberg-electromagnetic induced
transparency (EIT) atom array. Here, we show the interplay between EIT
effect and the Rydberg interaction results in the rich photon
statistics, and the propagation of the dark polaritons is studied.