Finite size cavity effect on nS rubidium Rydberg state lifetimes

In this work, we present lifetime measurements of nS states of Rb as a function of the principal quantum number (40 $⩽$ n $⩽$ 70) using a sample of cold atoms held in a magneto-optical trap, which is performed in a finite size metal vacuum chamber. The Rydberg states are excited through a two-photon transition, and detected by pulsed field ionization. Our measurements are larger than the predictions by well established theoretical model (1984 Phys. Rev. A 30 2881 and 2009 Phys. Rev. A 79 052504). We have implemented a theoretical model, which considers the vacuum chamber as a lossy Fabry–Perot cavity with a discrete spectrum, and compared with experimental results. Such comparison indicates that the blackbody radiation contribution on Rydberg state lifetime can be decreased by using a small size metal cavity, without the need of cryogenic environment. This effect may have application in experiments where longer Rydberg lifetimes are required. (paper)