Quantum traffic jam in far from equilibrium quantum systems
speaker: Giuliano Benenti (Università dell'Insubria)abstract: Low-dimensional systems are interesting for theoretical investigations, as they admit ordering tendencies, leading to collective quantum states that are difficult to realize in three-dimensional systems. Understanding the transport properties of such low-dimensional strongly correlated systems is a challenging open problem. So far, most of the theoretical studies concentrated on the close-to-equilibrium situation by using the linear response, while very little is known about the physics of such systems far from equilibrium. On the other hand, new quantum phases and interesting physical phenomena may appear in the far from equilibrium regime. It is shown that, when a finite anisotropic Heisenberg spin-12 chain in the gapped regime is driven far from equilibrium, oppositely polarized ferromagnetic domains build up at the edges of the chain, thus suppressing quantum spin transport. As a consequence, a negative differential conductivity regime arises, where increasing the driving decreases the current. This phenomenon arises as an outcome of the interplay between coherent quantum dynamics of the spin chain and incoherent spin pumping. Finally, the negative differential conductivity phenomenon is discussed in the context of charge transport in strongly correlated electron systems, i.e., for the Hubbard model. References: 1 G. Benenti, G. Casati, T. Prosen and D. Rossini, "Negative differential conductivity in far-from-equilibrium quantum spin chains", Europhys. Lett. 85, 37001 (2009). 2 G. Benenti, G. Casati, T. Prosen, D. Rossini and M. Znidaric, "Charge and spin transport in strongly correlated one-dimensional quantum systems driven far from equilibrium", Phys. Rev. B 80, 035110 (2009).
timetable:
Fri 6 Nov, 11:00 - 11:30, Aula Dini
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