A scheme is proposed wherein nuclear magnetic resonance (NMR) can be induced and monitored using only optical fields. In analogy to radio-frequency fields used in traditional NMR, circularly polarized light creates electron spins in semiconductors whose hyperfine coupling could tip nuclear moments. Time-resolved Faraday rotation experiments were performed in which the frequency of electron Larm...

The authors derive a general expression for the behavior of energy and dynamical quantum parameter an initially slow particle in arbitrary electromagnetic field electric type through short-time expansion combined with ultrarelativistic approximation. These results allow generalization effective threshold condition QED cascade onset.