Nondispersive two-electron wave packets in the collinear driven helium atom

Nondispersive two-electron wave packets are found in the Floquet spectrum of the driven, one-dimensional helium atom. In classical phase space, they are anchored to the principal nonlinear resonance between the collinear frozen planet orbit and the driving field linearly polarized along the orbit. These novel, highly correlated eigenstates of the driven three-body Coulomb problem exhibit lifetimes of the order of $10^3\ldots 10^7$ periods of the driving field, with strong fluctuations reminiscent of chaos-assisted tunneling