  Atoms exposed to high-frequency strong laser fields experience the ionization
suppression due to the deformation of Kramers-Henneberger (KH) wave functions,
which has not been confirmed yet in experiment. We propose a bichromatic
pump-probe strategy to affirm the existence of KH states, which is formed by
the pump pulse and ionized by the probe pulse. In the case of the single-photon
ionization triggered by a vacuum ultra-violet probe pulse, the double-slit
structure of KH atom is mapped to the photoelectron momentum distribution. In
the case of the tunneling ionization induced by an infrared probe pulse,
streaking in anisotropic Coulomb potential produces a characteristic momentum
drift. Apart from bichromatic schemes, the non-Abelian geometric phase provides
an alternative route to affirm the existence of KH states. Following specific
loops in laser parameter space, a complete spin flipping transition could be
achieved. Our proposal has advantages of being robust against focal-intensity
average as well as ionization depletion, and is accessible with current laser
facilities.
