Single-Photon Sources Based on Deterministic Quantum-Dot Microlenses

Abstract

This chapter addresses the design, fabrication and characterization of deterministically fabricated single-photon sources based on quantum dot microlenses. The quantum devices are optimized for future applications in quantum communication systems which require high photon extraction efficiency, strong suppression of multi-photon emission and high indistinguishability of the emitted photons. Highest extraction efficiency is achieved by integrating single quantum dots in the center of monolithic microlenses by means of in-situ electron-beam lithography based on low-temperature cathodoluminescence spectroscopy. Quantum optical studies of deterministic microlenses reveal pure single-photon emission associated with {\$}{\$}g^{\{}(2){\}}(0)<0.01{\$}{\$}and an indistinguishability exceeding 90{\%} under pulsed p-shell excitation. Mechanisms limiting the indistinguishability are discussed in terms of spectral diffusion at a nanosecond time-scale and phonon-induced dephasing. The chapter closes with an outlook on electrically driven quantum dot microlenses, the application of anti-reflection coatings and future perspectives.