Frequency conversion through Rydberg states

We demonstrate progress towards frequency conversion using four-wave mixing through Rydberg states in rubidium vapor. Excitation is accomplished through the intermediate 6p state using light at 420 nm generated through parametric four-wave mixing in combination with a 1015 nm laser. We demonstrate Electromagnetically Induced Transparency as a result of the Rydberg excitation transition. The application of microwaves then allows transitions between neighboring Rydberg states. When combined with a 780 nm laser, four-wave mixing through the Rydberg state can generate a beam at 480 nm. Even more promising is the potential to use six-wave mixing to accomplish microwave to optical frequency conversion. Microwaves resonant with a transition between nearby Rydberg states can cause the creation of light in the infrared. Several possible methods for accomplishing this conversion are outlined.