科研之友
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摘要
We study the real-time dynamics of spin chains driven out of thermal equilibrium by an initial temperature gradient T-L not equal T-R using density matrix renormalization group methods. We demonstrate that the nonequilibrium energy current saturates fast to a finite value if the linear-response thermal conductivity is infinite, i.e., if the Drude weight D is nonzero. Our data suggest that a nonintegrable dimerized chain might support such dissipationless transport (D > 0). We show that the steady-state value J(E) of the current for arbitrary T-L not equal T-R is of the functional form J(E) = f(T-L) - f(T-R), i.e., it is completely determined by the linear conductance. We argue for this functional form, which is essentially a Stefan-Boltzmann law in this integrable model; for the XXX ferromagnet, f can be computed via the thermodynamic Bethe ansatz in good agreement with the numerics. Inhomogeneous systems exhibiting different bulk parameters as well as Luttinger liquid boundary physics induced by single impurities are discussed briefly.
- 出版日期2013-11-15
