Non-linear doublon production in a Mott insulator --- Landau-Dykhne method applied to an integrable model

TL;DR

This paper analytically investigates doublon-hole pair production in a 1D Mott insulator under strong fields, revealing a crossover between multi-photon absorption and quantum tunneling, with implications for experimental detection and connections to quantum electrodynamics.

Contribution

It applies the Landau-Dykhne method combined with Bethe ansatz to analyze nonlinear doublon production, providing new insights into the crossover mechanisms in Mott insulators.

Findings

Identification of Keldysh crossover between absorption and tunneling.

Calculation of doublon-hole pair distribution functions.

Proposal of experimental tests such as angle-resolved photoemission spectroscopy.

Abstract

Doublon-hole pair production which takes place during dielectric breakdown in a Mott insulator subject to a strong laser or a static electric field is studied in the one-dimensional Hubbard model. Two nonlinear effects cause the excitation, i.e., multi-photon absorption and quantum tunneling. Keldysh crossover between the two mechanisms occurs as the field strength and photon energy is changed. The calculation is done analytically by the Landau-Dykhne method in combination with the Bethe ansatz solution and the results are compared with those of the time dependent density matrix renormalization group. Using this method, we calculate distribution function of the generated doublon-hole pairs and show that it drastically changes as we cross the Keldysh crossover line. After calculating the tunneling threshold for several representative one-dimensional Mott insulators, possible experimental tests of the theory is proposed such as angle resolved photoemission spectroscopy of the upper Hubbard band in the quantum tunneling regime. We also discuss the relation of the present theory with a many-body extension of electron-positron pair production in nonlinear quantum electrodynamics known as the Schwinger mechanism.