Highly sensitive detection of Rydberg atoms with fluorescence loss spectrum in cold atoms**Project supported by the National Key Research and Development Program of China (Grant Nos. 2017YFA0304203 and 2016YFF0200104), the National Natural Science Foundation of China (Grant Nos. 61505099, 61827824, 91536110, and 61975104), and the Fund for Shanxi ‘1331 Project’ Key Subjects Construction, Bairen Project of Shanxi Province, China.

Abstract

Fluorescence loss spectrum for detecting cold Rydberg atoms with high sensitivity has been obtained based on lock-in detection of fluorescence of 6P3/2 state when cooling lasers of the magneto-optical trap are modulated. The experiment results show that the signal to noise ratio has been improved by 32.64 dB when the modulation depth (converted to laser frequency) and frequency are optimized to 4 MHz and 6 kHz, respectively. This technique enables us to perform a highly sensitive non-destructive detection of Rydberg atoms.