Mainz 2026 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 59: QuanTour V – Protocols
Q 59.5: Talk
Thursday, March 5, 2026, 15:45–16:00, P 7
Benchmarking quantum key distribution by mixing single photons and laser light — •Yann Portella1, Petr Steindl1, Juan Rafael Álvarez1, Tim Hebenstreit2, Aristide Lemaître1, Martina Morassi1, Niccolo Somaschi3, Loïc Lanco1, Filip Rozpedek4, Pascale Senellart1, and Dario A. Fioretto1,3 — 1Centre de Nanosciences et de Nanotechnologies, Université Paris-Saclay, CNRS, Palaiseau, France — 2Max Planck Institute for the Science of Light, Erlangen, Germany — 3Quandela SAS, Massy, France — 4College of Information and Computer Science, University of Massachusetts Amherst, Amherst, Massachusetts, USA
Quantum key distribution stands out as a major application of quantum technologies, alongside quantum computing and quantum sensing. Many protocols require single photons, often approximated by dim laser pulses. Here, we propose a hybrid approach where the information is encoded with an incoherent mixture of single photons generated by a micropillar-embedded quantum dot and laser pulses. We show that there is an optimal mixture at any distance maximizing the secret key rate, benefiting both from the long distance scaling of single photons and high rate at short distance of laser light. This provides a flexible technology compensating for limited collected brightnesses of single-photon sources as well as a thorough investigation of advantage scenarios for single-photon and hybrid statistics. We highlight an efficiency threshold for unconditional advantage of single photons over laser light, and show insights on the interplay between single-photon purity and collected brightness in the performances of BB84.
Keywords: quantum optics; quantum key distribution; quantum dot; single photons; BB84