21 research outputs found
Exciton Recombination in One-Dimensional Organic Mott Insulators
We present a theory for the recombination of (charged) holons and doublons in
one-dimensional organic Mott insulators, which is responsible for the decay of
a photoexcited metallic state. Due to the charge-spin separation, the dominant
mechanism for recombination at low density of charges involves a multi-phonon
emission. We show that a reasonable coupling to phonons is sufficient to
explain the fast recombination observed by pump-probe experiments in
ET-FTCNQ, whereby we can also account for the measured pressure dependence
of the recombination rate.Comment: 5 + 3 pages, 2 figure
Iterative construction of conserved quantities in dissipative nearly integrable systems
Integrable systems offer rare examples of solvable many-body problems in the
quantum world. Due to the fine-tuned structure, their realization in nature and
experiment is never completely accurate, therefore effects of integrability are
observed only transiently. One way to surpass that is to couple nearly
integrable systems to baths and driving: these will stabilize integrable
effects up to arbitrary time, as encoded in the time dependent, and eventually,
the stationary state of form of a generalized Gibbs ensemble. However, the
description of such driven dissipative nearly integrable models is challenging
and no exact analytical methods have been proposed so far. Here we develop an
iterative scheme in which integrability breaking perturbations (baths)
determine the most necessary conserved quantities to be added into a truncated
generalized Gibbs ensemble description. Our scheme significantly reduces the
complexity of the problem, paving the way for thermodynamic results.Comment: 10 pages, 5 figures (including Supplemental Material
Holon-Doublon Binding as the Mechanism for the Mott transition
We study the binding of a holon to a doublon in a half-filled Hubbard model
as the mechanism of the zero-temperature metal-insulator transition. In a spin
polarized system and a non-bipartite lattice a single holon-doublon (HD) pair
exhibits a binding transition (e.g., on a face-centred cubic lattice), or a
sharp crossover (e.g., on a triangular lattice) corresponding well to the
standard Mott transition in unpolarized systems. We extend the HD-pair study
towards non-polarized systems by considering more general spin background and
by treating the finite HD density within a BCS-type approximation. Both
approaches lead to a discontinuous transition away from the fully polarized
system and give density correlations consistent with numerical results on a
triangular lattice.Comment: 6 pages, 4 figure
Dielectric breakdown in spin polarized Mott insulator
Nonlinear response of a Mott insulator to external electric field,
corresponding to dielectric breakdown phenomenon, is studied within of a
one-dimensional half-filled Hubbard model. It is shown that in the limit of
nearly spin polarized insulator the decay rate of the ground state into excited
holon-doublon pairs can be evaluated numerically as well to high accuracy
analytically. Results show that the threshold field depends on the charge gap
as . Numerical results on small systems indicate
on the persistence of a similar mechanism for the breakdown for decreasing
magnetization down to unpolarised system.Comment: 4 pages, 6 figure
Reconstructing effective Hamiltonians from nonequilibrium (pre-)thermal steady states
Reconstructing Hamiltonians from local measurements is key to enabling
reliable quantum simulation: both validating the implemented model, and
identifying any left-over terms with sufficient precision is a problem of
increasing importance. Here we propose a deep-learning-assisted variational
algorithm for Hamiltonian reconstruction by pre-processing a dataset that is
diagnosed to contain thermal measurements of local operators. We demonstrate
the efficient and precise reconstruction of local Hamiltonians, while
long-range interacting Hamiltonians are reconstructed approximately. Away from
equilibrium, for periodically and random multipolar driven systems, we
reconstruct the effective Hamiltonian widely used for Floquet engineering of
metastable steady states. Moreover, our approach allows us to reconstruct an
effective quasilocal Hamiltonian even in the heating regime beyond the validity
of the prethermal plateau, where perturbative expansions fail.Comment: 13 pages, 5 figure