Magic Frequencies in Atom-Light Interaction for Precision Probing of the Density Matrix


  Yair Margalit [1]  ,  Menachem Givon [1]  ,  Amir Waxman [1]  ,  Tal David [2]  ,  David Groswasser [1]  ,  Yonathan Japha [1]  ,  Ron Folman [1]  
[1] Ben-Gurion University of the Negev
[2] Israel Aerospace Industries, Ramta Division

We analyze theoretically and experimentally the existence of a magic frequency for which the absorption of a linearly polarized light beam by vapor alkali-metal atoms is independent of the population distribution among the Zeeman sub-levels and the angle between the beam and a magnetic field. The phenomenon originates from a peculiar cancelation of the contributions of higher moments of the atomic density matrix, and is described using the Wigner-Eckart theorem and inherent properties of Clebsch-Gordan coefficients. One important application is the robust measurement of the hyperfine population.