Nonclassical lattice solitons in optical lattice via Electromagnetically induced transparency

An optical four-level atomic discrete system through optical induction is proposed. A theoretical scheme to produce nonclassical lattice solitons (NLS) in the system is presented with the use of the effects of enhanced self-phase modulation and the giant kerr effect in the electromagnetically induced transparency. The power density and the photon flux can be tuned to a very low level by the controlling field and the soliton can propagate with very slow group velocity. By changing the sign of the detuning $\Delta_{1}$, both in-phase and $\pi$ out-of-phase NLSs can be produced in this system.