Adiabatic potentials for Rydberg atoms in a ponderomotive optical lattice

We calculate the adiabatic potentials and adiabatic wavefunctions of Rydberg atoms in a one-dimensional ponderomotive optical lattice. All lattice-induced couplings between the degenerate high-angular-momentum Rydberg states are taken into account. To obtain insight into the underlying physics, we analyze the numerical results in terms of effective electric and magnetic fields produced by the lattice. Near the inflection points of the lattice potential and for sufficiently low principal quantum numbers (n less than or similar to 35 in the cases studied), the adiabatic level structure resembles that of the dc Stark effect, and an effective electric-field model can be used to model the lattice-induced perturbation. Near the nodes and anti-nodes of the lattice field, the adiabatic level structure exhibits a combination of adjacent rotational and vibrational energy level sequences. Here, an analogy between the ponderomotive optical lattice and the diamagnetic problem works well to interpret the lattice-induced perturbation in terms of an effective magnetic field.