Topological effects in dissipative quantum systems (Marcel Wagner)

  • Date: Apr 26, 2018
  • Time: 11:00 AM - 12:00 PM (Local Time Germany)
  • Speaker: Marcel Wagner
  • Institut für theoretische Physik, Universität Stuttgart
  • Room: B 0.42 (small room in the livrary)
  • Host: MPQ, Theory Division
The concept of topological order seems to be understood on a high level in dissipation-free quantum systems, i.e. in absence of a reservoir or bath.

By contrast, an extension of topologically protected phases to the dissipative scenario remains an open question that is addressed in resent research.
In the talk two different ways of introducing effects of dissipation to a quantum system are used. Both allow for a generalization of the notion of topological phases to open quantum systems. Within an effective description, which uses complex potentials, it is shown that a non-Hermitian analog of the Berry phase features a strict quantization and hence suits as a topological invariant of the dissipative system. This concept is transferred to the more general framework of Lindblad master equations treated within the scope of superoperators. Both descriptions are exemplified by a system showing topologically nontrivial phases in absence of dissipation, viz. the Su-Schrieffer-Heeger model coupled to different types of reservoirs.

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