Carrier-envelope-phase control of asymmetries in the multiphoton ionization of xenon atoms by ultrashort bichromatic fields

Abstract

We report on bichromatic multiphoton ionization of xenon atoms (Xe) to demonstrate carrier-envelope-phase (CEP) control of lateral asymmetries in the photoelectron momentum distribution. In the experiments, we employ a $4f$ polarization pulse shaper to sculpture bichromatic fields with commensurable center frequencies ${\ensuremath{\omega}}_{1}:{\ensuremath{\omega}}_{2}=7:8$ from an over-octave-spanning CEP-stable white light supercontinuum by spectral amplitude and phase modulation. The bichromatic fields are spectrally tailored to induce controlled interferences of 7- vs 8-photon quantum pathways in the $5{P}_{3/2}$ ionization continuum of Xe. The CEP sensitivity of the asymmetric final-state wave function arises from coherent superposition of continuum states with opposite parity. Our results demonstrate that shaper-generated bichromatic fields with tailored center frequency ratio are a suitable tool to localize CEP-sensitive asymmetries in a specific photoelectron kinetic-energy window.