T. Opatrny et Dg. Welsch, Coupled cavities for enhancing the cross-phase-modulation in electromagnetically induced transparency - art. no. 023805, PHYS REV A, 6402(2), 2001, pp. 3805
We propose an optical double-cavity resonator whose response to a signal is
similar to that of an electromagnetically induced transparency (EIT) mediu
m. A combination of such a device with a four-level EIT medium can serve fo
r achieving large cross-Kerr modulation of a probe field by a signal field.
This would offer the possibility of building a quantum logic gate based on
photonic qubits. We discuss the technical requirements that are necessary
for realizing a probe-photon phase shift of pi caused by a single-photon si
gnal. The main difficulty is the requirement of an ultralow reflectivity be
am splitter, and we must be able to operate a sufficiently dense cool EIT m
edium in a cavity.