2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/29261Coherent emission of light by a split excitonic Bose-Einstein condensate -- excitonic Josephson junction -- can be extremely sensitive to the Josephson phase established across the junction. As a result of this, the emission can be redistributed between different directions and even cancelled. The cases of the dipole- and of the quadrupole-active excitons are considered.5 RevTeX pages, no figures, replaced with revised version ( references added, and minor typos corrected)Mesoscale and Nanoscale PhysicsStatistical Mechanicstext