Carrier-envelope phase-dependent quantum interferences in multiphoton ionization

The angular distribution of photoelectrons created by multiphoton ionization of xenon atoms by a few-cycle laser pulse shows a carrier-envelope phase (CEP) dependent asymmetry. A simple perturbative model based on a sum over indistinguishable quantum paths describes the observed asymmetry as a function of photoelectron energy and CEP. Although the individual multiphoton transition rates depend on the intensity profile of the pulse, the experimentally measured photoelectron angular distributions are sensitive to the absolute spectral phase of the pulse, including both CEP and chirp. We discuss retrieval of the CEP and chirp from the asymmetry pattern, as well as the potential to extract the scattering phase shift.