Magic frequencies in atom-light interaction for precision probing of the density matrix    [PDF]

Menachem Givon, Yair Margalit, Amir Waxman, Tal David, David Groswasser, Yonathan Japha, Ron Folman
We analyze theoretically and experimentally the existence of a {\it magic frequency} for which the absorption of a linearly polarized light beam by vapor alkali 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.
View original: http://arxiv.org/abs/1306.1151