ISBN 9783843942232

978-3-8439-4223-2, Reihe Physik

Marc Sartison
Fabrication of efficient single-photon devices based on pre-selected quantum dots using deterministic optical lithography

263 Seiten, Dissertation Universität Stuttgart (2019), Softcover, A5

Zusammenfassung / Abstract

The foundation of modern secure communication technologies, metrology applications and the more and more demanding computational needs are based on using non-classical quantum states. For instance, quantum computation mostly relies on superconducting qubits. Despite the good performances in computing, these kind of quantum bits cannot be transmitted over distances. Instead, transmission of encrypted information, even over long distances, can be achieved via photons as flying qubits. There are several possibilities for the mandatory creation of single and indistinguishable photons, such as atoms, parametric down-conversion sources or solid state-based sources as color centers in diamond and semiconductor quantum dots. Among these, semiconductor quantum dots have shown their versatility. Outstanding optical properties were shown in terms of on-demand generation of pure single-photon emission, indistinguishable photons and even entangled photon pairs which is one of the building blocks of modern quantum repeaters.

However, one of the major drawbacks in quantum optics based on solid-state sources is the limited brightness due to the high refractive index contrast at the solid-air interface. The effect of total internal reflection prevents efficient outcoupling of the emitted photons. Overcoming this issue and increasing the source brightness will be fundamental in the future for the realization of experiments which require high photon fluxes. Due to well established fabrication techniques in industry, semiconductor quantum dot-based devices are the ideal choice when it comes to process flexibility.

The work in this thesis pushed the concept of in-situ lithography even further. The achieved results provide a significant increase in process flexibility and shows that the in-situ lithography concept can be applied to emitters in any desired wavelength regime from the red up to the telecom bands.