Direct imaging of atoms

J. David Wong-Campos, K. G. Johnson, Brian Neyenhuis +2 more

Feng Wang, Chunfang Wang, Jing Cheng +1 more

In this paper, a special gradient-index electromagnetically induced transparency medium is induced with a Gaussian control field, which can be realized in a four-level ⁸⁷Rb cold atomic cloud. Special directional self-imaging and imaging transforming properties are studied in this work. Simulated results show that a complex object can be imaged in the cold atoms, as the control field substituted with the elliptical Gaussian beam, then the self-imaging is directional, which has potental application in encryption.

Wilhelm G. Kaenders, Frank Lison, A. Richter +2 more

Chunfang Wang, Feng Wang, Li-Ru Yang

We show the influences of temperature on the self-imaging in the coherent atomic system which consists of four-level 87 Rb atoms. The different-direction self-imaging, the corresponding imaging quality, and the imaging contrast ratio in this Doppler broadening medium are studied. As a result, the imaging-position linearly increases with the temperature, while the quality of the self-imaging does not show clear connection with the temperature. Due to the weaker mutual interference in the higher temperature, the contrast ratios in the two directions increase. The interesting results are important and may have potential applications in imaging storage and processing.

Yu. B. Ovchinnikov

Emine Altuntaş, Ian B. Spielman

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 I sat . 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 I sat 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.