Polarized neutron interferometry has been used to measure the amplitudes for the exchange of up to five photons between the neutron and an oscillating magnetic field. The Rabi spin flip configuration and a configuration in which spin flip is suppressed were investigated, because they raise different questions on the conservation of angular momentum. Because of the linearity of the time-dependent interference signal in the exchange amplitudes, photon exchange probabilities below 1% could be resolved.

• Received 24 May 1995

DOI:https://doi.org/10.1103/PhysRevLett.75.3206