Polaron master equation theory of pulse driven phonon-assisted population inversion and single photon emission from quantum dot excitons

TL;DR

This paper develops a semi-analytical polaron master equation approach to model pulse-driven phonon-assisted population inversion and single photon emission in quantum dot excitons, aligning well with experimental results.

Contribution

It introduces a new semi-analytical polaron master equation method that captures phonon effects and time-dependent driving in quantum dots, providing insights into population dynamics and photon emission.

Findings

The theory agrees with experimental observations of phonon-induced population inversion.

Quantum dots in cavities show different population responses depending on excitation method.

Resonant cavity coupling with phonon assistance is less efficient than direct Rabi oscillations for single photon generation.

Abstract

We introduce an intuitive and semi-analytical polaron master equation approach to model pulse-driven population inversion and emitted single photons from a quantum dot exciton. The master equation theory allows one to identify important phonon-induced scattering rates analytically, and fully includes the role of the time-dependent pump field. As an application of the theory, we first study a quantum dot driven by a time-varying laser pulse on and off resonance, showing the population inversion caused by acoustic phonon emission in direct agreement with recent experiment of Quilter {\em et al.}, Phys Rev Lett {\bf 114}, 137401 (2015). We then model quantum dots in weakly coupled cavities and show the difference in population response between exciton-driven and cavity-driven systems. Finally, we assess the nonresonant phonon-assisted loading scheme with a quantum dot resonantly coupled to a cavity as a deterministic single photon source, and compare and contrast the important figures of merit with direct Rabi oscillation of the population using a resonant $\pi$ pulse, where the latter is shown to be much more efficient.