Measurement of the dipole-dipole interaction of Rbnsnpstates by microwave Ramsey interferometry

Abstract

We have used the Ramsey method of separated oscillatory fields to probe the dipole-dipole interaction of Rb $nsnp$ pair states of $33\ensuremath{\le}n\ensuremath{\le}41$. In the Ramsey method dipole-dipole broadening in an inhomogeneous sample is manifested as a decrease in the fringe contrast with increasing density. An attractive feature of this approach compared to conventional line broadening is that the effect of the dipole-dipole interaction can be seen near the center of the Ramsey interference pattern, where the signal is large, as opposed to in the wings, where it is small. We observe dipole-dipole broadening which scales as ${n}^{4}$, in agreement with the calculated broadening. In addition, the Ramsey method points to the existence of $nsn{p}_{1/2}$ states which have no dipole-dipole shift.