Limitations of rotating-wave approximation in magnetic resonance: Characterization and elimination of the Bloch-Siegert shift in magneto-optics

TL;DR

This paper investigates the Bloch-Siegert shift in rubidium vapor, demonstrating the limitations of the rotating-wave approximation and proposing a new experimental scheme to eliminate systematic errors, thereby improving spectroscopic accuracy.

Contribution

It characterizes the Bloch-Siegert shift in magneto-optics and develops a method to eliminate this systematic error in magnetic resonance measurements.

Findings

Demonstrated the limitations of the rotating-wave approximation.

Supported experimental results with numerical calculations.

Developed an experimental scheme free from the Bloch-Siegert shift.

Abstract

We present investigations of radio-frequency resonances observed in a rubidium vapor. With measurements of a systematic shift of radio-frequency resonances, induced by an off-resonance component of an oscillating field (the Bloch-Siegert shift), we demonstrate limitations of the rotating-wave approximation. Experimental results are supported with numerical calculations, reproducing all features of the observed signals. Based on the studies, we develop experimental scheme free from the problem. By liberating the measurements from a systematic error (the resonance shift), the new approach will increase accuracy of spectroscopic measurements and magnetic-field detection.