Measurement and modelling of enhanced absorption Hanle effect resonances in 85 Rb

We present a theoretical and experimental study of the resonant circularly-polarized-light-induced Hanle effect in the ground state of Cs vapor atoms in a paraffin-coated cell. The effect manifests itself as a narrow resonance (centered at B = 0) in the dependence of the optical transmission coefficient of the vapor on the magnitude of an external magnetic field B. We develop a theoretical model that yields an algebraic expression for the shape of these resonances for arbitrary field orientations and arbitrary angular momenta of the states coupled by the exciting light, provided that the light power is kept sufficiently small. An experimental procedure for assessing the range of validity of the model is given. Experiments were carried out on the laser-driven Cs D 1 transition both in longitudinal and transverse field geometries, and the observed line shapes of the corresponding bright and dark resonances give an excellent confirmation of the model predictions. The method is applied for determining the intrinsic longitudinal and transverse relaxation rates of the vector magnetization in the vapor and their dependence on light power.

Section: Introductionmentioning

confidence: 99%

Measurement of longitudinal and transverse spin relaxation rates using the ground-state Hanle effect

Castagna

Weis

2011

“…However, the latter approach is not well suited to extract characteristic system parameters, such as relaxation rate(s), by data fitting procedures. A third approach just uses empirical line shape functions to analyze the resonances [17], but gives little insight into the underlying mechanisms of the GSHE.…”

Section: A Scope Of the Present Workmentioning

confidence: 99%

Ground-state Hanle effect based on atomic alignment

Breschi

Weis

2012

We have studied the ground-state Hanle effect (GSHE) excited by linearly polarized laser light on the D 1 line of cesium atoms. We have solved algebraically the Liouville equation using the irreducible tensor formalism, and derive an analytical expression for the resonance line shapes in a magnetic field of arbitrary direction. The model predictions are in excellent agreement with experimental observations in various field geometries. Our model is valid for arbitrary F → F transitions in the low-power limit. We discuss the relation between the GSHE and electromagnetically induced transparency or absorption. Our approach allows a full understanding of the mechanism of the GSHE and provides tools for quantifying the resonance contrast, a crucial parameter for metrological applications of level crossing resonances.

“…The dark and bright resonances are the phenomena of EIT and electromagnetically induced absorption (EIA) [19][20][21], respectively. There have been many reports on CPT and EIT experiments in the Hanle configuration using alkali-metal atoms, such as 87 Rb, 85 Rb, K, and Cs in either a pure or buffer-gas-filled cell [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. In the context of the effect of the external parameters on the CPT spectra, such as a stray magnetic field or the polarization of the laser beam, Nasyrov et al [28] reported a CPT experiment in the Hanle configuration for Cs atoms in a pure cell using an elliptically polarized beam and explained the results using a simple theoretical model.…”

Section: Introductionmentioning

confidence: 99%

Calculated Hanle transmission and absorption spectra of theRb87D1line with residual magnetic field

Noh

Moon

2010

This paper reports a theoretical study on the transmission spectra of an arbitrarily polarized laser beam through a rubidium cell with or without a buffer gas in Hanle-type coherent population trapping (CPT). This study examined how laser polarization, transverse magnetic field, and collisions with buffer gas affects the spectrum. The transmission spectrum due to CPT and the absorption spectrum due to the level crossing absorption (LCA) were calculated according to the laser polarization. The results show that the LCA is strongly dependent on the transverse magnetic field and interaction time of the atoms with a laser light via collisions with the buffer gas. In addition, the spectral shape of the calculated Hanle spectrum is closely related to the direction between the (stray) transverse magnetic field and polarization of the laser.