Jan 5th-8th, 2016

Yukawa Institute for Theoretical Physics, Kyoto University

"Flux quench in a system of interacting spinless fermions in one dimension"

Yuya Nakagawa (Univ. of Tokyo)

We study a quantum quench in a one-dimensional spinless fermion model (equivalent to the S=1/2 XXZ chain), where a magnetic flux is suddenly turned off. This quench is equivalent to imposing a pulse of electric field and therefore generates an initial particle current. This current is not a conserved quantity in presence of the lattice and the interactions, and thus shows a nontrivial time-evolution after the quench. We investigate this phenomenon numerically, using the infinite time-evolving block decimation (iTEBD) method. For repulsive interactions or large initial flux, we find oscillations that are governed by excitations deep inside the Fermi sea. At long times we observe that the current acquires some finite value in the gapless cases, whereas it decays to zero in the gapped cases. Although the linear response theory (valid for a weak flux) predicts the same long-time limit of the current for repulsive and attractive interactions (relation with the zero-temperature Drude weight), larger nonlinearities are observed in the case of repulsive interactions compared with that of the attractive case.

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