Detector Placement Relaxes Efficiency Requirements for Detecting a Weak Coherent Link

Abstract

A weak coherent link can produce unusually early arrivals without changing stationary count rates. Missed jumps along routes available without the link can produce similar records, obscuring its presence. On an eight-site ring, relocating the same detector losses exposes one more crossing on the easiest background route to hide, without changing the dynamics or leading link signal. At fixed error and a common observation-time scaling, the tolerated missed fraction and time-bin width follow fourth-root rather than square-root scaling with link strength. These requirements hold for every decision using the counting record and are met using three event counts per bin, with all elapsed time included. At the same stationary collected flux, where jumps are monitored can therefore determine the time resolution needed for weak-link sensing.