Measurement scheme for relative phase diffusion between two Bose-Einstein condensates

We propose a method of measuring diffusion of the relative phase between tw o Bose-Einstein condensates occupying different nuclear or electronic spin hyperfine slates coupled by a two-photon magnetic-dipole transition via an intermediate level. Due to the macroscopic quantum coherence the condensate s can be decoupled from the electromagnetic fields. The rate of decoherence and the phase collapse may be determined from the occupation of the interm ediate level or the absorption of radiation. [S1050-2947(99)50404-6].