Measurement and numerical calculation of Rubidium Rydberg Stark spectra

Abstract

We report on the measurement of Stark shifted energy levels of $^{87}$Rb\nRydberg atoms in static electric fields by means of electromagnetically induced\ntransparency (EIT). Electric field strengths of up to 500V/cm, ranging beyond\nthe classical ionisation threshold, were applied using electrodes inside a\nglass cell with rubidium vapour. Stark maps for principal quantum numbers\n$n=35$ and $n=70$ have been obtained with high signal-to-noise ratio for\ncomparison with results from ab initio calculations following the method\ndescribed in [M. L. Zimmerman et al., Phys. Rev. A 20, 2251 (1979)], which was\noriginally only verified for states around $n=15$. We also calculate the dipole\nmatrix elements between low-lying states and Stark shifted Rydberg states to\ngive a theoretical estimate of the relative strength of the EIT signal. The\npresent work significantly extends the experimental verification of this\nnumerical method in the range of both high principal quantum numbers and high\nelectric fields with an accuracy of up to 2MHz.\n