From the key composite quantum system made of a two-level system (qubit) and a harmonic oscillator (photon) with resonant or dispersive interactions, one derives the corresponding quantum stochastic master equations (sme) when either the qubits or the photons are measured.
Starting with an elementarydiscrete-time formulation based on explicit formulae for the interaction
propagators, one shows how to include measurement imperfections and decoherence induced by the environment.
In six years data of the magnetospheric multi-scale mission, a four-satellite constellation crossing mostly turbulent regions of magnetic reconnection and collecting about 95\% of the data outside the quieter solar wind, deviations have been found from the maxwellian law due to a photon mass, real for the de broglie-proca theory, or effective for the lorentz-poincar\'e symmetry violation (lsv) in the extension of the standard-model (sm).
Deviations might be due to unaccounted experimental errors or to non-maxwellian terms.