Macrodimers: Ultralong Range Rydberg Molecules

We study long range interactions between two Rydberg atoms and predict the existence of ultralong range Rydberg dimers with equilibrium distances of many thousands of Bohr radii. We calculate the dispersion coefficients [Formula presented], [Formula presented], and [Formula presented] for two rubidium atoms in the same excited level [Formula presented] and find that they scale like [Formula presented], [Formula presented], and [Formula presented], respectively. We show that for certain molecular symmetries these coefficients lead to long range potential wells that can support molecular bound levels. Such macrodimers would be very sensitive to their environment and could probe weak interactions. We suggest experiments to detect these macrodimers.