Quantum interferences from cross talk in $J=1/2\leftrightarrow J=1/2$   transitions
  We consider the possibility of a control field opening up multiple pathways and thereby leading to new interference and coherence effects. We illustrate the idea by considering the $J=1/2\leftrightarrow J=1/2$ transition. As a result of the additional pathways, we show the possibilities of nonzero refractive index without absorption and gain without inversion. We explain these results in terms of the coherence produced by the opening of an extra pathway. 
Shubhrangshu Dasgupta