A Langevin canonical approach to the dynamics of chiral systems: populations and coherences.

A canonical framework for chiral two-level systems coupled to a bath of harmonic oscillators is developed to extract, from a stochastic dynamics, the thermodynamic equilibrium values of both the population difference and coherences. The incoherent and coherent tunneling regimes are analyzed for an Ohmic environment in terms of a critical temperature defined by the maximum of the heat capacity. The corresponding numerical results issued from solving a non-linear coupled system of equations are fitted to approximate path-integral analytical expressions beyond the so-called non-interacting blip approximation in order to determine the different time scales governing both regimes.