Eur. Phys. J. D 27, 193-199 (2003)
https://doi.org/10.1140/epjd/e2003-00253-y

EIT-assisted atomic squeezing

¹ Laboratoire Kastler Brossel, Case 74, 4 place Jussieu, 75252 Paris Cedex 05, France
² Michigan Center for Theoretical Physics, FOCUS Center, and Physics Department, University of Michigan, Ann Arbor, Michigan 48109-1120, USA

Corresponding author: ^a pinard@spectro.jussieu.fr

Received: 10 February 2003
Revised: 28 May 2003
Published online: 12 August 2003

Abstract

The interaction of classical and quantized electromagnetic fields with an ensemble of atoms in an optical cavity is considered. Four fields drive a double-Λ level scheme in the atoms, consisting of a pair of Λ systems sharing the same set of lower levels. Two of the fields produce maximum coherence, , between the ground state sublevels 1 and 2. This pumping scheme involves equal intensity fields that are resonant with both the one- and two-photon transitions of the Λ system. There is no steady-state absorption of these fields, implying that the fields induce a type Electromagnetically-Induced Transparency (EIT) in the medium. An additional pair of fields interacting with the second Λ system, combined with the EIT fields, leads to squeezing of the atom spin associated with the ground state sublevels. Our method involves a new mechanism for creating steady-state spin squeezing using an optical cavity. As the cooperativity parameter C is increased, the optimal squeezing varies as . For experimentally accessible values of C, squeezing as large as 90% can be achieved.