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HL: Fachverband Halbleiterphysik

HL 7: Transport: Quantum coherence and quantum information systems - Theory (TT with HL)

HL 7.12: Vortrag

Montag, 16. März 2015, 12:30–12:45, H 3005

Dissipation-induced first order decoherence phase transition in a non-interacting fermionic system — •Mihailo Cubrovic — Institute for Theoretical Physics, Universität zu Köln, Zülpicher Str. 77, D-50937, Köln, Germany

We consider a dissipative tight-binding fermionic chain as a model for a nanowire with current leakage due to imperfect isolation. The dissipation manifests as tunneling into/out of the chain from/to the environment. The evolution of the system is described by the Lindblad equation, generalized to incorporate the memory effects in the bath. Already infinitesimally small dissipation along the chain induces a quantum phase transition (QPT). This is a decoherence QPT: the reduced density matrix of a subsystem (far from the ends of the chain) can be represented as the tensor product of single-site density matrices. We analyze the QPT in the thermodynamic limit by looking at the entropy and the response function in the bulk, and compare in detail the results with and without memory in the bath. To gain a better intuitive understanding we also contruct the analogous classical model (a correlated random walk process) and compare its behavior to the QPT of the quantum chain.