Robust and Stable Delay Interferometers with Application to d -Dimensional Time-Frequency Quantum Key Distribution
Nurul T. Islam, Clinton Cahall, Andrés Aragoneses, A. Lezama, Jungsang Kim, Daniel J. Gauthier · Physical Review Applied · 2017
For secure communication, quantum key distribution using high-dimensional quantum states---$q\phantom{\rule{0}{0ex}}u\phantom{\rule{0}{0ex}}d\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}s$, rather than qubits---can overcome many experimental nonidealities, and achieve higher secure-key rates than with qubits. However, high-dimensional systems are difficult to implement, especially when eavesdropping is monitored via frequency, as the devices required to measure these frequency states are complex. Using commercially available gear, the authors build a ``tree of interferometers'' with the potential to achieve record-breaking secure-key rates.