Josephson Effects in a Bose-Einstein Condensate of

A phenomenological theory is developed, that accounts for the collective dy-namics of a Bose-Einstein condensate of magnons. In terms of such descrip-tion we discuss the nature of spontaneous macroscopic interference between magnon clouds, highlighting the close relation between such effects and the well known Josephson effects. Using those ideas we present a detailed cal-culation of the Josephson oscillations between two magnon clouds, spatially separated in a magnonic Josephson junction