Bichromatic field generation from double-four-wave mixing in a double-electromagnetically induced transparency system

We demonstrate double electromagnetically induced transparency (double-EIT) and double four-wave mixing (double-FWM) based on a new scheme of non-degenerate four-wave mixing (FWM) involving five levels of a cold 85Rb atomic ensemble, in which the double-EIT windows are used to transmit the probe field and enhance the third-order nonlinear susceptibility. The phase-matching conditions for both four-wave mixings can be satisfied simultaneously. The frequency of one component of the generated bichromatic field is less than the other by ground-state hyperfine splitting (3 GHz). This specially designed experimental scheme for simultaneously generating different nonlinear wave-mixing processes is expected to find applications in quantum information processing and cross-phase modulation. Our results agree well with the theoretical simulation. (paper)