Larmor Precession and Tunneling Time of a Non-RelativisticNeutral Spin-1/2 Particle Through an Arbitrary Potential Barrier

We investigate the Larmor precession of a non-relativistic neutral spin-1/2 particle in a uniform constant magnetic field confined to the region of a one-dimensional arbitrary potential barrier. With the help of a general spin coherent state it is explicitly shown that the spin precession time is equal to the dwell time. For the special case of symmetric rectangular potential barrier, the precession time is also in agreement with the transmission time. We present a numerical estimation of the precession time showing an apparent superluminal tunneling.