a Department of Physics and Institute of Theoretical Physics, Shanxi University, Taiyuan, Shanxi 030006, China;b State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
Abstract:
The Larmor precession of a neutral spin- particle in a uniform constant magnetic field confined to the region of a one-dimensional rectangular potential well is investigated. The spin precession serves as a clock to measure the time spent by a quantum particle dwelling at a potential well. With the help of a general spin coherent state it is explicitly shown that the spin precession time is equal to the dwell time. The comparison of the time in a potential well with that in free space shows apparent superluminality.