Phonon-mediated population inversion in a semiconductor quantum-dot cavity system

S Hughes,H J Carmichael

doi:10.1088/1367-2630/15/5/053039

S Hughes, H J Carmichael

Open Access

https://doi.org/10.1088/1367-2630/15/5/053039

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Abstract

We investigate pump-induced exciton inversion in a quantum-dot cavity system with continuous wave drive. Using a polaron-based master equation, we demonstrate excited-state populations above 0.9 for an InAs quantum dot at a phonon bath temperature of 4 K. In an exciton-driven system, the dominant mechanism is incoherent excitation from the phonon bath. For cavity driving, the mechanism is phonon-mediated switching between ground- and excited-state branches of the ladder of photon states, as quantum trajectory simulations clearly show. The exciton inversion as a function of detuning is found to be qualitatively different for exciton and cavity driving, primarily due to cavity filtering. The master equation approach allows us to include important radiative and non-radiative decay processes on the zero phonon line, provides a clear underlying dynamic in terms of photon and phonon scattering, and admits simple analytical approximations that help to explain the physics.

Highlights

The ability to achieve inversion and lasing in atomic and solid state systems is a topic of continuing interest [1]
We focus on the fundamental mechanisms available to achieve population inversion in a semiconductor quantum dots (QDs)-cavity system
QDs are embedded in a solid state lattice where electron-phonon interactions, though sometimes ignored in quantum optical studies, are known to impact optical properties; they affect photoluminescence lineshapes [13], coherent Rabi oscillation [14], and the Mollow triplet spectrum of resonance fluorescence [15, 16]; phonon-mediated scattering can cause excitation-induced dephasing [14, 17], which is detrimental to the exploitation of quantum optical interactions

Summary

Introduction

The ability to achieve inversion and lasing in atomic and solid state systems is a topic of continuing interest [1]. QDs are embedded in a solid state lattice where electron-phonon interactions, though sometimes ignored in quantum optical studies, are known to impact optical properties; they affect photoluminescence lineshapes [13], coherent Rabi oscillation [14], and the Mollow triplet spectrum of resonance fluorescence [15, 16]; phonon-mediated scattering can cause excitation-induced dephasing [14, 17], which is detrimental to the exploitation of quantum optical interactions It is interesting, to ask what impact this scattering has when one tries to coherently drive an excitonic transition coupled to a quantized radiation mode into a regime of population inversion [4,5,6].

Theory

Results

Conclusions