A spin laser?: The persistent processing domain in superfluid 3He-B at ultralow temperatures

We discuss various properties of the persistent precessing domain (PPD, formerly PIS) in superfluid He-3-B. These exotic NMR domains can only be excited at ultralow temperatures. At the lowest temperatures they freely precess for periods up to 2000 s. We identify various behaviors depending on the texture and magnetic field profile. We can create the domains with small generating pulses or excite them continuously but only with an excitation frequency higher than that of the domain precession. Remarkably, we can excite and sustain the precession by the application of white noise. Thus,. unusually, the coherent domain can extract energy from an incoherent energy source. (C) 2003 Published by Elsevier Science B.V.