Abstract

In biology as well as in quantum information protocols, efficient light sources based on nanoemitters are of great interest. For quantum cryptography, single photons sources, with high quantum yield but also efficient emission collection, are needed. Colloidal CdSe nanocrystals (NCx) are very good candidates for these purposes, as they are versatile and efficient single photon sources at the individual scale. For quantum gates, coherence time of the emission is crucial but its measurement, at cryogenic temperature, remains challenging for single CdSe NCx as they suffer of phase diffusion. A recent experiment proved that their coherence time is larger than 200ps [1], But the measurement was limited by the collection efficiency, especially low when the sample is inside a cryostat, and an objective with a quite low numerical aperture has to be used. The purpose of this paper is to propose a configuration for which emission efficiency and far field collection of single NCx can be increased.

© 2009 IEEE