Quantum Key Distribution with a Negatively Charged Quantum Dot Single-Photon Source

Various quantum key distribution protocols require bright single-photon sources with a very low probability of multiphoton emission. In this work, we investigate single-photon generation from a negatively charged quantum dot embedded in an elliptical pillar microcavity, driven using either resonant excitation or adiabatic rapid passage (ARP). Our results show that ARP excitation significantly suppresses multiphoton emission probability and improves photon indistinguishability compared to resonant excitation. We further evaluate the secure key rate of both BB84 and twin-field quantum key distribution (TF-QKD) using quantum-dot single-photon sources and compare their performance with that of Poisson-distributed photon sources (PDS) such as weak coherent pulses and down-conversion sources. The analysis reveals that adiabatic excitation offers a modest but consistent enhancement in secure key rate relative to resonant excitation. Moreover, quantum-dot single-photon sources outperform PDS sources over short and intermediate distances; however, at longer distances, PDS sources eventually surpass quantum-dot sources in both infinite decoy-state BB84 and TF-QKD.