Quantum dynamics of mixed polarization states: effects of environment-mediated intermode coupling

Abstract

We study the quantum dynamics of mixed polarization states represented by the two-mode boson system interacting with an environment. Using the form of general dynamical equations for averaged operators that preserve normal ordering, we show that the dynamical regimes of the averaged Stokes operators crucially depend on the anisotropy of the relaxation operator resulting from the intermode coupling induced by the anisotropic environment. We analyze how this coupling impacts the quantum bit error rate in the well-known single-photon polarization-coding quantum key distribution protocol BB84.