Key generation efficiency, and security, in DPS-QKD improve with an increase in the number of path delays or time-bin superpositions. We demonstrate the implementation of super-position states using time-bins, and establish an equivalence with path-based superposition, thus yielding a simpler implementation of higher-order superposition states for differential phase-shift quantum key distribution (DPS-QKD). We set up DPS-QKD, over 105 km of single mode optical fiber, with a quantum bit error rate of less than 15% at a secure key rate of 2 kbps. With temporal guard bands, the QBER reduced to less than 10%, but with a 20% reduction in the key rate.
@article{arxiv.2008.03083,
title = {Equivalence of space and time-bins in DPS-QKD},
author = {Gautam Shaw and Shyam Sridharan and Shashank Ranu and Foram Shingala and Prabha Mandayam and Anil Prabhakar},
journal= {arXiv preprint arXiv:2008.03083},
year = {2022}
}