  We present a new trajectory formulation of high harmonic generation that
treats classically allowed and classically forbidden processes within a single
dynamical framework. Complex trajectories orbit the nucleus, producing the
stationary Coulomb ground state. When the field is turned on, these complex
trajectories continue their motion in the field-dressed Coulomb potential and
therefore tunnel ionization, unbound evolution and recollision are described
within a single, seamless framework. The new formulation can bring mechanistic
understanding to a broad range of strong field physics effects.
