“…the 2 3 S 1 metastable level of 4 He, with F = 1 [25]). Its five components, which obey m (2) −q = (−1) q (m (2) q ) * , can be represented by the column matrix [23,24,26,27] M = (m (2) −2 , m (2) −1 , m (2) 0 , m (2) 1 , m (2) 2 ) t . This alignment is subject to several concurrent processes: preparation of the gas state by optical pumping, relaxation, evolution under the magnetic field, and optical measurement.…”