Noncyclic Pancharatnam phase for mixed state SU(2) evolution in neutron polarimetry

Abstract We have measured the Pancharatnam relative phase for spin- 1 / 2 states. In a neutron polarimetry experiment the minima and maxima of intensity modulations, giving the Pancharatnam phase, were determined. We also considered general SU ( 2 ) evolution for mixed states. The results are in good agreement with theory.