Photocurrent of exciton polaritons

TL;DR

This paper derives a formula for exciton polariton photocurrent in inversion-broken systems, showing it depends on polariton density and requires broken time reversal symmetry, with applications in probing nonequilibrium dynamics.

Contribution

It introduces a theoretical framework for polariton photocurrent, linking it to symmetry breaking and providing a simulation of its time evolution after excitation.

Findings

Polariton photocurrent is proportional to polariton density.

Opposite signs for upper and lower polariton branches.

Photocurrent can be used to probe nonequilibrium dynamics.

Abstract

We study photocurrent of exciton polaritons in inversion broken systems. We use an effective Hamiltonian and Green's function approaches to deduce the formula for polariton photocurrent. The obtained formula shows the polariton photocurrent is proportional to the polariton density and shows opposite signs for the upper and lower branches. Nonvanishing polariton photocurrent requires time reversal symmetry breaking in addition to inversion symmetry breaking. We show that exciton states in transition metal dichalcogenides such as MoS$_2$ support polariton photocurrent once we break time reversal symmetry by applying magnetic fields or using photons with circular polarization. We also perform a simulation based on a rate equation and study a time profile of polariton photocurrent after pulse excitation, which indicates that the photocurrent provides a useful nonlinear probe to study nonequilibrium dynamics of exciton polaritons.