















Nonreciprocal breather
Condensed matter theory
Nonreciprocal breathing solitons
Breathing solitons consist of a fast-beating wave within a compact envelope of stable shape and velocity. The phenomenon has been demonstrated in plasmas, optical fibers and cold atoms but has yet to be experimentally observed in systems that dissipate energy. Here, we report breathing, unidirectional, arbitrarily long-lived solitons in non-reciprocal, non-conservative active metamaterials and analyse their dynamics.