  The rotating frame is considered in quantum mechanics on the basis of the
position dependent boost relating this frame to the non rotating inertial
frame. We derive the Sagnac phase shift and the spin coupling with the rotation
in the non relativistic limit by a simple treatment. By taking the low energy
limit of the Dirac equation with a spin connection, we obtain the Hamiltonian
for the rotating frame, which gives rise to all the phase shifts discussed
before. Furthermore, we obtain a new phase shift due to the spin-orbit
coupling.
