Theoretical Nanophysics

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Transport properties of one-dimensional systems from finite temperature dynamical DMRG

Christoph Karrasch, University of California

17.12.2012 at 16:00 

We propose an easily implemented approach to study time-dependent correlation functions of one dimensional systems at finite temperature T using the density matrix renormalization group. The entanglement growth inherent to any time-dependent calculation is significantly reduced if the auxiliary degrees of freedom which purify the statistical operator are time evolved with the physical Hamiltonian but reversed time. We exploit this to investigate linear-response and nonequilibrium charge and heat transport properties of spin chains; we concretely address the following questions:
Can we quantitatively compute the Drude weight D of the integrable XXZ chain?
Can a model still support dissipationless transport (D>0) in presence of a nonintegrable perturbation?
If not, how is the conductivity regularized by such a perturbation, and how does it scale with T? Can we calculate AC conductivities?
How does the nonequilibrium current driven by an arbitrary temperature gradient look like - and can it be related to linear response transport properties?

C 112 - Theresienstr. 41