Long-distance quantum key distribution using concatenated entanglement swapping with practical resources

We present our approach for sharing photons and assessing resultant four-photon visibility between two distant parties using concatenated entanglement swapping. In addition we determine the corresponding key generation rate and the quantum bit-error rate. Our model is based on practical limitations of resources, including multipair parametric down-conversion sources, inefficient detectors with dark counts and lossy channels. Through this approach, we have found that a trade-off is needed between experimental run-time, pair-production rate and detector efficiency. Concatenated entanglement swapping enables huge distances for quantum key-distribution but at the expense of low key generation rate

Robustness of the BB84 quantum key distribution protocol against general coherent attacks

It is demonstrated that for the entanglement-based version of the Bennett-Brassard (BB84) quantum key distribution protocol, Alice and Bob share provable entanglement if and only if the estimated qubit error rate is below 25% or above 75%. In view of the intimate relation between entanglement and security, this result sheds also new light on the unconditional security of the BB84 protocol in its original prepare-and-measure form. In particular, it indicates that for small qubit error rates 25% is the ultimate upper security bound for any prepare-and-measure BB84-type QKD protocol. On the contrary, for qubit error rates between 25% and 75% we demonstrate that the correlations shared between Alice and Bob can always be explained by separable states and thus, no secret key can be distilled in this regime.Comment: New improved version. A minor mistake has been eliminate

Writing in a Culture in Conflict

Panel: Writing in a Culture in Conflic

Inclusive Entrepreneurship Model for Person with Disabilities: A Critical Reflection

Persons with Disabilities are one of the marginalized communities that struggle economically and socially. Entrepreneurship has been considered one of the best options; however, PWDs are struggling in their business journey. The study investigates factors of the inclusive entrepreneurship model of Persons with Disabilities through their reflection. A focus group semi-structured interview was conducted with ten selected PWDs based on their entrepreneurship experience. Data were analyzed using a thematic analysis approach. Findings show that psychological issues and social discrimination are major entrepreneurship obstacles. Therefore, entrepreneurship programs for PWDs should be more disabled-friendly and focus on their physical and emotional needs