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Direct calibration of laser intensity via Ramsey interferometry for cold atom imaging

Abstract

A majority of ultracold atom experiments utilize resonant absorption imaging techniques to obtain the atomic density. To make well-controlled quantitative measurements, the optical intensity of the probe beam must be precisely calibrated in units of the atomic saturation intensity Isat. In quantum gas experiments, the atomic sample is enclosed in an ultra-high vacuum system that introduces loss and limits optical access; this precludes a direct determination of the intensity. Here, we use quantum coherence to create a robust technique for measuring the probe beam intensity in units of Isat via Ramsey interferometry. Our technique characterizes the ac Stark shift of the atomic levels due to an off-resonant probe beam. Furthermore, this technique gives access to the spatial variation of the probe intensity at the location of the atomic cloud. By directly measuring the probe intensity just before the imaging sensor our method in addition yields a direct calibration of imaging system losses as well as the quantum efficiency of the sensor.

Publication Details

Authors
Publication Type
Journal Article
Year of Publication
2023
Journal
Optics Express
Volume
31
Issue
11
Date Published
05/2023
Publisher
Optica Publishing Group
Pagination
17893
ISSN
1094-4087

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