Floquet engineering of interparticle correlations in electron-hole few-body system for strong radial confinement.

Abstract

We investigate the effects of off-resonant THz-frequency laser light coupling to bound few-body electron-hole system, i.e. the exciton and negatively charged trion confined in quantum wire. To solve this problem, we first conduct a unitary Hennerberger-Kramers transformation of the Hamiltonian and diagonalize its perturbative approximation to obtain the exciton and trion Floquet states. Within this framework, the light-matter coupling renormalizes an attractive $eh$ interaction, leaving the repulsive $ee$ unchanged, thus modifying corresponding two-particle correlation energies. Generally, the correlation energy of $eh$ would exceed the $ee$ one for a semiconductor material with strongly localized heavy holes. However, as the former is weakened by increasing laser intensity, this relation can be reversed. Consequently, the trion may dissociate unconventionally, the hole gradually decouples from still strongly interacting electrons, and adequate energy and optical spectra changes accompany this process. The energy levels of the exciton and trion Floquet states are raised, while their optical brightness smoothly decreases for stronger laser intensities. We also show this process can be further modified by breaking the mirror symmetry of wire with a static electric field, and then the occurrence of the avoided crossings between the lowest energy levels of the trion depends on the laser intensity. These anticrossings shall be observed experimentally, confirming thus the usefulness of Floquet engineering for fast manipulations of the few-particle states in electron-hole systems on a subpicosecond time scale.