Intrinsic and environmental effects on the interference properties of a high-performance quantum dot single photon source

TL;DR

This study combines experiments and theory to analyze how intrinsic and environmental factors affect the interference and indistinguishability of photons emitted from a quantum dot single photon source, revealing key dephasing mechanisms.

Contribution

It provides a comprehensive experimental and theoretical analysis of interference properties and dephasing mechanisms in a high-performance quantum dot single photon source under various conditions.

Findings

Near-perfect photon interference at 2 ns pulse separation with 99.6% indistinguishability.

Interference contrast decreases with larger pulse separation, higher pump power, and increased temperature.

Photon indistinguishability is unaffected by pump power under resonant excitation but is impacted by virtual phonon processes.

Abstract

We report a joint experimental and theoretical study of the interference properties of a single photon source based on a In(Ga)As quantum dot embedded in a quasi-planar GaAs-microcavity. Using resonant laser excitation with a pulse separation of 2 ns, we find near-perfect interference of the emitted photons, and a corresponding indistinguishability of $\mathcal{I} = (99.6\,^{+\,0.4}_{-\,1.4})\%$. For larger pulse separations, quasi-resonant excitation conditions, increasing pump power or with increasing temperature, the interference contrast is progressively and notably reduced. We present a systematic study of the relevant dephasing mechanisms, and explain our results in the framework of a microscopic model of our system. For strictly resonant excitation, we show that photon indistinguishability is independent of pump power, but strongly influenced by virtual phonon assisted processes which are not evident in excitonic Rabi oscillations.