# Measurement of the lifetime of the $7s^2S_{1/2} $ state in atomic cesium using asynchronous gated detection

## TL;DR

This paper measures the lifetime of the cesium 7s state using advanced photon detection techniques, providing precise experimental data to test theoretical models relevant for fundamental physics tests.

## Contribution

It introduces a novel asynchronous gated detection method for accurate lifetime measurement of atomic states in vapor cells.

## Key findings

- Measured the cesium 7s state lifetime as 48.28±0.07 ns
- Achieved an uncertainty of 0.14% in the lifetime measurement
- Demonstrated the effectiveness of asynchronous gated detection for atomic spectroscopy

## Abstract

We report a measurement of the lifetime of the cesium $7s\,^2S_{1/2}$ state using time-correlated single-photon counting spectroscopy in a vapor cell. We excite the atoms using a Doppler-free two-photon transition from the $6s\,^2S_{1/2}$ ground state, and detect the 1.47$\mu$m photons from the spontaneous decay of the $7s\,^2S_{1/2}$ to the $6p\,^2P_{3/2}$ state. We use a gated single photon detector in an asynchronous mode, allowing us to capture the fluorescence profile for a window much larger than the detector gate length. Analysis of the exponential decay of the photon count yields a $7s\,^2S_{1/2}$ lifetime of 48.28$\pm$0.07ns, an uncertainty of 0.14%. These measurements provide sensitive tests of theoretical models of the Cs atom, which play a central role in parity violation measurements.