An optical lattice loaded with cold atoms can exhibit a tunable photonic band gap for a weak probe field under the conditions of electromagnetically induced transparency. This system possesses a number of advantageous properties, including reduced relaxation of Raman coherence and the associated probe absorption, and simultaneous enhancement of the index modulation and the resulting reflectivity of the medium. This flexible system has the potential to serve as a test bed for various designs of linear and nonlinear photonic band gap materials at very low light level and can be employed to realize deterministic entanglement between weak quantum fields.

• Received 25 June 2007

DOI:https://doi.org/10.1103/PhysRevA.76.053823