Use of Autoionization to Detect 88-Sr Rydberg Atoms

Rydberg atoms are frequently detected by selective field ionization, in which a ramped externally applied electric field is used to induce ionization. However, at low n, the electric fields required for such ionization, ~1/16(n-δ)⁴ a.u., are not readily achievable in practice. In this regime, autoionization induced by excitation of the Rydberg core ion provides a valuable alternative for Rydberg atom detection. This approach is well suited to alkali-earth species as the core ion is optically active and the required excitation wavelengths can be conveniently generated using visible or near UV laser systems [1]. Here, we describe progress towards implementing this detection scheme for 88-Sr Rydberg atoms, exploiting the 422 nm 5s ²S_1/2 → 5p ²P_1/2 transition in the core ion and detecting the product Sr⁺ ions using a channeltron detector for the study of ultralong-range molecules and quantum simulation.

[1] Lochead, G., Boddy, D., Sadler, D. P., Adams, C. S., and Jones, M. P. A. Number-resolved imaging of excited-state atoms using a scanning autoionization microscope. Phys. Rev. A 87 (May 2013), 053409