Pulse shaping for on-demand emission of single Raman photons from a quantum-dot biexciton

TL;DR

This paper demonstrates theoretically that tailored laser pulses can enable on-demand emission of high-purity, indistinguishable single Raman photons from quantum dots, despite complex decay channels and quantum interference.

Contribution

It introduces a method using non-trivial shaped laser pulses to control Raman photon emission in quantum dots, incorporating phonon effects for realistic predictions.

Findings

On-demand Raman photon emission is achievable with tailored laser pulses.

High photon purity and indistinguishability are maintained.

Phonon-mediated processes are included in the model.

Abstract

Semiconductor quantum dots embedded in optical cavities are promising on-demand sources of single photons. Here, we theoretically study single photon emission from an optically driven two-photon Raman transition between the biexciton and the ground state of a quantum dot. The advantage of this process is that it allows all-optical control of the properties of the emitted single photon with a laser pulse. However, with the presence of other decay channels and excitation-induced quantum interference, on-demand emission of the single Raman photon is generally difficult to achieve. Here we show that laser pulses with non-trivial shapes can be used to maintain excitation conditions for which with increasing pulse intensities the on-demand regime is reached. To provide a realistic picture of the achievable system performance, we include phonon-mediated processes in the theoretical caluclations. While preserving both high photon purity and indistinguishability, we find that although based on a higher-order emission process, for realistic system parameters on-demand Raman photon emission is indeed achievable with suitably tailored laser pulses.