944 research outputs found
Dielectric Breakdown of a Mott Insulator
We study the nonequilibrium steady state of a Mott insulator coupled to a
thermostat and driven by a constant electric field, starting from weak fields,
until the dielectric breakdown, and beyond. We find that the conventional Zener
picture does not describe the steady-state physics. In particular, the current
at weak field is found to be controlled by the dissipation. Moreover, in
connection with the electric-field-driven dimensional crossover, we find that
the dielectric breakdown occurs when the field strength is on the order of the
Mott gap of the corresponding lower-dimensional system. We also report a
resonance and the meltdown of the quasiparticle peak when the field strength is
half of this Mott gap.Comment: 5 pages, 5 figures. v2: references adde
Impurity model for non-equilibrium steady states
We propose an out-of-equilibrium impurity model for the dynamical mean-field
description of the Hubbard model driven by a finite electric field. The
out-of-equilibrium impurity environment is represented by a collection of
equilibrium reservoirs at different chemical potentials. We discuss the
validity of the impurity model and propose a non-perturbative method, based on
a quantum Monte Carlo solver, which provides the steady-state solutions of the
impurity and original lattice problems. We discuss the relevance of this
approach to other non-equilibrium steady-state contexts.Comment: 5 pages, 4 figure
Permanent spin currents in cavity-qubit systems
In a recent remarkable experiment [P. Roushan et al., Nature Physics 13, 146
(2017)], a spin current in an architecture of three superconducting qubits was
produced during a few microseconds by creating synthetic magnetic fields. The
life-time of the current was set by the typical dissipative mechanisms that
occur in those systems. We propose a scheme for the generation of permanent
currents, even in the presence of such imperfections, and scalable to larger
system sizes. It relies on striking a subtle balance between multiple
nonequilibrium drives and the dissipation mechanisms, in order to engineer and
stimulate chiral excited states which can carry current.Comment: 4 pages, 3 figure
Landau Theory for Non-Equilibrium Steady States
We examine how systems in non-equilibrium steady states close to a continuous
phase transition can still be described by a Landau potential if one forgoes
the assumption of analyticity. In a system simultaneously coupled to several
baths at different temperatures, the non-analytic potential arises from the
different density of states of the baths. In periodically driven-dissipative
systems, the role of multiple baths is played by a single bath transferring
energy at different harmonics of the driving frequency. The mean-field critical
exponents become dependent on the low-energy features of the two most singular
baths. We propose an extension beyond mean field.Comment: 18 pages. v2: minor edit
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