Spin Coherent State Path Integral for the Interaction of Two-Level System with Time Dependent Non-Uniform Magnetic Field

We study the movement of a two-level atom in interaction with time dependent nonuniform magnetic filed using the path integral formalism. The propagator is first written in the standard form by replacing the spin by a unit vector aligned along the polar and azimuthal directions. Then it is determined exactly using perturbation methods. Thus the Rabi formula of the system are deduced.

Treatment of Spin-1/2 Particle in Interaction with a Time-Dependent Magnetic Field by the Fermionic Coherent-State Path-Integral Formalism

We consider a spin-1/2 particle interacting with a time-dependent magnetic field using path integral formalism. The propagator is first of all written in the standard form replacing the spin by two fermionic oscillators via the Schwinger model. The propagator is then exactly determined, thanks to a simple transformation, and the transition probability is deduced.