We consider spinless fermions on a finite one-dimensional lattice, interacting via nearest-neighbor repulsion and subject to a strong electric field. In the non-interacting case, due to Wannier-Stark localization, the single-particle wave functions are exponentially localized even though the model has no quenched disorder. We show that this system remains localized in the presence of interactions and exhibits physics analogous to models of conventional many-body localization (MBL). In particular, the entanglement entropy grows logarithmically with time after a quench, albeit with a slightly different functional form from the MBL case, and the level statistics of the many-body energy spectrum are Poissonian. We moreover predict that a quench experiment starting from a chargedensity wave state would show results similar to those of Schreiber et al. [Science 349, 842 (2015)]. arXiv:1808.01250v2 [cond-mat.dis-nn]

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We consider a single atom in an optical lattice, subject to a harmonic trapping potential. The problem is treated in the tight-binding approximation, with an extra parameter kappa denoting the strength of the harmonic trap. It is shown that the kappa-->0 limit of this problem is singular, in the sense that the density of states for a very shallow trap (kappa-->0) is qualitatively different from that of a translationally invariant lattice (kappa=0). The physics of this difference is discussed, and densities of states and wave functions are exhibited and explained.

This paper is concerned with the out-of-equilibrium two-lead Kondo model, considered as a model of a quantum dot in the Kondo regime. We revisit the perturbative expansion of the dot's magnetization, and conclude that, even at order 0 in the Kondo interactions, the magnetization is not given by the usual equilibrium result. We use the Schwinger-Keldysh method to derive a Dyson equation describing the steady state induced by the voltage between the two leads, and thus present the correct procedure for calculating perturbative expansions of steady-state properties of the system.where angle-brackets . . . denote an expectation value taken in the steady (i.e. long-time) state of the system. M Pauli is simply the Pauli paramagnetic contribution from the lead electrons which would be present even in the absence of the impurity, and which we therefore exclude from M tot . We consider the perturbative expansions of these steady state quantities; more precisely, we define: