Our article, Theory of high-efficiency sum-frequency generation for single-photon waveform conversion, by John Donohue, Mike Mazurek, and Kevin Resch was just published in Physical Review A. The article studies the problem of single photon frequency conversion using sum-frequency generation, calculating how well the properties of the upconverted photon match a simpler first-order approximation.
Abstract: The optimal properties for single photons may vary drastically between different quantum technologies. Along with central frequency conversion, control over photonic temporal waveforms will be paramount to the effective coupling of different quantum systems and efficient distribution of quantum information. Through the application of pulse shaping and the nonlinear optical process of sum-frequency generation, we examine a framework for manipulation of single-photon waveforms. We use a nonperturbative treatment to determine the parameter regime in which both high-efficiency and high-fidelity conversion may be achieved for Gaussian waveforms and study the effect such conversion techniques have on energy-time entanglement. Additionally, we prove that aberrations due to time ordering are negligible when the phase matching is nonrestrictive over the input bandwidths. Our calculations show that ideal quantum optical waveform conversion and quantum time lensing may be fully realized using these techniques.