Precise measurement of hyperfine intervals using avoided crossing of dressed states

• Published in: Europhysics letters 2002-10, Vol.60 (2), p.195-200
• Main Authors: Rapol, U. D, Natarajan, V
• Format: Article
• Language: English
• Subjects: 32.10.Fn; 42.50.Gy; Atomic and molecular physics; Atomic properties and interactions with photons; Exact sciences and technology; Fine and hyperfine structure; Physics; Properties of atoms and atomic ions
• ISSN: 0295-5075; 1286-4854
• DOI: 10.1209/epl/i2002-00338-1

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 $\chem{Rb}$ vapor, we obtain a precision of 44$\un{kHz}$. This is a significant improvement over the current precision of $\sim 1$ $\un{MHz}$.