Lasing at half the Josephson frequency with exponentially long coherence times

摘要: We describe a superconducting device capable of producing laser light in the visible range at half Josephson generation frequency, with optical phase locked to difference. An earlier proposed device, so-called “half-Josephson laser” [ Phys. Rev. Lett. 107 073901 (2011)], cannot provide long coherence times, because spontaneous switchings between emitter states. To circumvent this we consider N?1 emitters driving an resonator mode. derive general model that captures essential physics such devices while not depending on specific microscopic details. find conditions under which times are exponentially long, thus surpassing fundamental limitation common lasers. For study noise device. In particular, interested rate large fluctuations field limit where typical small. The responsible for switching stable states radiation and therefore determine time.