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Q: Fachverband Quantenoptik und Photonik

Q 25: Poster: Quantum Optics and Photonics I

Q 25.33: Poster

Tuesday, March 12, 2019, 16:30–18:30, S Atrium Informatik

Topological phases of mixed states and their detection — •Lukas Wawer and Michael Fleischhauer — TU Kaiserslautern

Topological states of matter have fascinated physicists since a long time due to the exotic properties of elementary excitations and the topological protection of edge states and currents. Motivated by topological charge pumps, we will introduce a classification for topological phases of matter applicable to finite-temperature states as well as stationary states of driven, dissipative systems based on a generalization of the many-body polarization. For non-interacting fermions it defines an ensemble topological phase (ETP), which in the thermodynamic limit is the Zak or Berry phase of a ficticious Hamiltonian given by the covariance matrix of single-particle correlations [1]. As examples, we discuss a Thouless pump in steady state of the one dimensional finite-temperature Rice-Mele model and a scheme that maps the covariance matrix to the hamiltonian of an auxiliary system of free fermions at T=0. This allows to directly observe the ficticious Hamiltonian and the same scheme can be used to transfer topological properties from an interacting to a non-interacting system. [1]C.E. Bardyn, L. Wawer, A. Altland, M. Fleischhauer, S.Diehl, Phys. Rev. X (2018)