A manifestly gauge-invariant description of interaction of atomic systems with strong fields in the dipole approximation

摘要: Abstract We propose a new type of gauge-invariant expansion the ionization probability amplitudes atoms by short pulses electromagnetic radiation. Contrary to previous approaches this problem it does not require different partitions total Hamiltonian depending on choice gauge. In natural way atomic potential is treated as perturbation acting an electron interacting with strong pulse. Whereas standard assumption field approximation (SFA), we show that grouping consequently together all terms same order in results amplitude which gauge invariant , and only limit infinite series. approach, illustrated numerical examples, “direct ionization” “rescattering” contributions are from those commonly used SFA-calculations.