Phys.org July 3, 2024
Quantum key distribution (QKD) enables secure communication. Semiconductor quantum dots (QDs) are a promising building block for quantum communication applications because of the deterministic emission of single photons with high brightness and low multiphoton contribution. Researchers in Germany reported on the first intercity QKD experiment using a bright deterministic single photon source. A BB84 [one time pad encryption] protocol based on polarisation encoding was realized using the high-rate single photons in the telecommunication C-band emitted from a semiconductor QD embedded in a circular Bragg grating structure. Utilizing the 79 km long link (equivalent to 130 km for the direct-connected optical fibre) between two German cities a record-high secret key bits per pulse of 4.8 × 10−5 with an average quantum bit error ratio were demonstrated. According to the researchers deterministic semiconductor sources challenge state-of-the-art QKD protocols and have the potential to excel in measurement device independent protocols and quantum repeater applications… read more. Open Access TECHNICAL ARTICLE
Overview of the intercity QKD experiments on the ‘Niedersachsen quantum link’… Credit: Light: Science & Applications volume 13, Article number: 150 (2024)