Precise measurement of hyperfine intervals using avoided crossing of dressed states

Department of Physics, Indian Institute of Science - Bangalore 560 012, India

Corresponding author: vasant@physics.iisc.ernet.in

Received: 2 May 2002
Accepted: 28 July 2002

Abstract

We demonstrate a technique for precisely measuring hyperfine intervals in alkali atoms. The atoms form a three-level Λ system in the presence of a strong control laser and a weak probe laser. The dressed states created by the control laser show significant linewidth reduction. We have developed a technique for Doppler-free spectroscopy that enables the separation between the dressed states to be measured with high accuracy even in room temperature atoms. The states go through an avoided crossing as the detuning of the control laser is changed from positive to negative. By studying the separation as a function of detuning, the center of the level-crossing diagram is determined with high precision, which yields the hyperfine interval. Using room temperature vapor, we obtain a precision of 44. This is a significant improvement over the current precision of .