  We consider effects of strong light-matter interaction on electronic friction
in molecular junctions within generic model of single molecule nano cavity
junction. Results of the Hubbard NEGF simulations are compared with mean-field
NEGF and generalized Head-Gordon and Tully approaches. Mean-field NEGF is shown
to fail qualitatively at strong intra-system interactions, while accuracy of
the generalized Head-Gordon and Tully results is restricted to situations of
well separated intra-molecular excitations, when bath induced coherences are
negligible. Numerical results show effects of bias and cavity mode pumping on
electronic friction. We demonstrate non-monotonic behavior of the friction on
the bias and intensity of the pumping field and indicate possibility of
engineering friction control in single molecule junctions.
