Localizing high-lying Rydberg wave packets with two-color laser fields

We demonstrate control over the localization of high-lying Rydberg wave packets in argon atoms with phase-locked orthogonally polarized two-color laser fields. With a reaction microscope, we measure ionization signals of high-lying Rydberg states induced by a weak dc field and blackbody radiation as a function of the relative phase between the two-color fields. We find that the dc-field-ionization yield of high-lying Rydberg argon atoms oscillates with the relative two-color phase with a period of 2 pi while the photoionization signal by blackbody radiation shows a period of pi. Accompanying simulations show that these observations are a clear signature of the asymmetric localization of electrons recaptured into very elongated (low angular momentum) high-lying Rydberg states after conclusion of the laser pulse. Our findings thus open an effective pathway to control the localization of high-lying Rydberg wave packets.Austrian Science Fund (FWF) [P25615-N27, P28475-N27, P21463-N22, P23359-N16]; National Natural Science Foundation of China [11574010]; National Program on Key Basic Research Project (973 Program) [2013CB922402]; [SFB-041 ViCoM]; [SFB-049 NextLite]; [W1243]SCI(E)ARTICLE29