Level-crossing resonances on open atomic transitions in a buffered Cs vapor cell: Linewidth narrowing, high contrast and applications to atomic magnetometry

Abstract

The ground-state Hanle effect (GSHE) in alkali-metal atomic vapors using a single circularly polarized wave underlies one of the most robust and simplest techniques in atomic magnetometry. This effect causes a narrow (subnatural-width) resonance in the light wave intensity transmitted through a vapor cell. Usually, GSHE-based sensors operate in the spin-exchange-relaxation-free (SERF) regime. However, this regime requires a relatively high temperature of vapors (150 C or higher), leading to a relatively large heat release and power consumption of the sensor head. Besides, without applying special measures, SERF regime significantly limits a dynamic range of measurements. Here, we study a pump-probe scheme involving a single elliptically polarized wave and a polarimetric detection technique. The wave is in resonance with two adjacent optical transitions in the cesium D1 line (894.6 nm) owing to their overlapping in presence of a buffer gas (Ne, 130 Torr). Using a small (0.1 cm${}^3$) glass vapor cell, we demonstrate a possibility of observing subnatural-width resonances with a high contrast-to-width ratio (up to 45 %/mG) under a low-temperature (60 C) regime of operation thanks to a strong light-induced circular dichroism. Basing on a $\Lambda$ scheme of atomic energy levels, we obtain explicit analytical expressions for the line shape. The model reveals a linewidth narrowing effect due to openness of the scheme. This result is unusual for magneto-optical atomic spectroscopy because the openness is commonly considered as a undesirable effect, degrading the resonance characteristics. We estimate a sensitivity of 1.8 pT/$\surd$Hz with a 60 fT/$\surd$Hz sensitivity in the photon-shot-noise limit. The results contribute to the theory of GSHE resonances and can be applied to development of a low-temperature high-sensitivity miniaturized magnetic field sensor with an extended dynamic range.

18 pages, 11 figures

References in corpus (4)

• F-resolved Magneto-optical Resonances at D1 Excitation of Cesium: Experiment and Theory
• Magneto-optical resonance of electromagnetically induced absorption with high contrast and narrow width in a vapour cell with buffer gas
• Zero-field magnetometry based on the combination of atomic orientation and alignment
• The missing quantum number of the Floquet states

Cited by in corpus (5)

• How to build a magnetometer with thermal atomic vapor: A tutorial
• All-optical atomic magnetometry using an elliptically polarized amplitude-modulated light wave
• All-optical measurement of magnetic fields for quantum gas experiments
• Modulation transfer spectroscopy of ${}^7$Li D1 line
• Atomic magnetometry based on the ground-state Hanle effect in an elliptically polarized light wave