Precision lifetime measurement of the cesium $6P_{3/2}$ level using ultrafast pump-probe laser pulses

TL;DR

This paper reports a highly precise measurement of the cesium 6P3/2 excited state lifetime using ultrafast pump-probe laser pulses, with detailed analysis of systematic errors and potential improvements.

Contribution

It introduces an improved ultrafast pump-probe method for measuring atomic excited state lifetimes with detailed systematic error analysis.

Findings

Measured cesium 6P3/2 lifetime as 30.462(46) ns

Achieved measurement uncertainty of 0.15%

Identified key systematic errors affecting precision

Abstract

Using the inherent timing stability of pulses from a mode-locked laser, we have precisely measured the cesium $6P_{3/2}$ excited state lifetime. An initial pump pulse excites cesium atoms in two counter-propagating atomic beams to the $6P_{3/2}$ level. A subsequent synchronized probe pulse ionizes atoms which remain in the excited state, and the photo-ions are collected and counted. By selecting pump pulses which vary in time with respect to the probe pulses, we obtain a sampling of the excited state population in time, resulting in a lifetime value of 30.462(46) ns. The measurement uncertainty (0.15%) is larger than our previous report of 0.12% [Phys. Rev. A 84, 010501(R) (2011)] due to the inclusion of additional data and systematic errors. In this follow-up paper we present details of the primary systematic errors encountered in the measurement, which include atomic motion within the intensity profiles of the laser beams, quantum beating in the photo-ion signal, and radiation trapping. Improvements to further reduce the experimental uncertainty are also discussed