Controlling the photon number coherence of solid-state quantum light sources for quantum cryptography

Yusuf Karli, Daniel A. Vajner, Florian Kappe, Paul C.A. Hagen, Lena M. Hansen, René Schwarz, Thomas K. Bracht, Christian Schimpf, Saimon F. Covre da Silva, Philip Walther, Armando Rastelli, Vollrath Martin Axt, Juan C. Loredo, Vikas Remesh, Tobias Heindel, Doris E. Reiter, Gregor Weihs

Quantum communication networks rely on quantum cryptographic protocols including quantum key distribution (QKD) based on single photons. A critical element regarding the security of QKD protocols is the photon number coherence (PNC), i.e., the phase relation between the vacuum and one-photon Fock state. To obtain single photons with the desired properties for QKD protocols, optimal excitation schemes for quantum emitters need to be selected. As emitters, we consider semiconductor quantum dots, that are known to generate on-demand single photons with high purity and indistinguishability. Exploiting two-photon excitation of a quantum dot combined with a stimulation pulse, we demonstrate the generation of high-quality single photons with a controllable degree of PNC. The main tuning knob is the pulse area giving full control from minimal to maximal PNC, while without the stimulating pulse the PNC is negligible in our setup for all pulse areas. Our approach provides a viable route toward secure communication in quantum networks.

Quantum Optics, Quantum Nanophysics and Quantum Information
External organisation(s)
Leopold-Franzens-Universität Innsbruck, Technische Universität Berlin, Universität Bayreuth, Technische Universität Dortmund, Westfälische Wilhelms-Universität Münster, Johannes Kepler Universität Linz
npj Quantum Information
No. of pages
Publication date
Peer reviewed
Austrian Fields of Science 2012
103025 Quantum mechanics, 103021 Optics
ASJC Scopus subject areas
Computer Science (miscellaneous), Statistical and Nonlinear Physics, Computer Networks and Communications, Computational Theory and Mathematics
Portal url