2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/97174We study quantum key distribution with standard weak coherent states and show, rather counter-intuitively, that the detection events originated from vacua can contribute to secure key generation rate, over and above the best prior art result. Our proof is based on a communication complexity/quantum memory argument.4 pagesQuantum Physicstext