“Nonlocality-of-a-single-photon” based Quantum Key Distribution and Random Number Generation schemes and their device-independent security analysis
Konrad Schlichtholz, Bianka Woloncewicz, Tamoghna Das, Marcin Markiewicz, and Marek Żukowski
Quantum 10, 2084 (2026). https://doi.org/10.22331/q-2026-04-28-2084 The question of “non-locality of a single photon'', which started with a paper by Tan, Walls and Collett (TWC, 1991) stirred a thirty years long debate. This hampered attempts to use the TWC interferometric scheme in quantum cryptography. The scheme involves a single photon 50-50 beam-split into two modes propagating to two spatially separated observation stations at which weak homodyne measurements are made. The physics and non