Orientational Light Shift Experimental Estimate of 0-0 Resonance Frequency in Rubidium Vapor

The paper presents the measurements results of the orientational light shift of the radio-optical 0-0 resonance frequency in the rubidium vapor with isotopic pumping. The experiments were done on a laboratory quantum discriminator, the functional diagram of which contained a known element set for rubidium frequency standard on a gas cell. The discriminator was placed in the three identical pairs of Helmholtz coils, 50 cm in diameter, which created a working magnetic field (10 μT, 3 μT, and 1 μT) in the area of the gas cell. Helmholtz coils were connected to alternating voltage sources to create a rotating magnetic field relative to the normal to the direction of the pumping light. To weaken external magnetic noise and inhomogeneities of the laboratory magnetic field, the entire system was placed in a magnetic shield with a screening factor of ~ 10³, which practically made it possible to exclude the effect of the residual field on the measurements accuracy. The main experimental results are formulated as follows: the orientational frequency shift of the 0-0 radio-optical resonance does not depend on the magnitude of the working magnetic field and is linearly related to the pumping light intensity; when the working magnetic field is oriented normal to the quantum discriminator optical axis, the tensor and scalar components of the light shift have equal (positive) signs, which at any temperature of the filter-cell leads to their impossible compensation; when the working magnetic field is oriented along the quantum discriminator optical axis, the tensor and scalar components of the light shift have opposite signs, which at the corresponding temperature of the filter-cell leads to their possible (partial) compensation.