Broadening the bandwidth of entangled photons: A step towards the generation of extremely short biphotons

Abstract

We demonstrate a technique that allows full control of the bandwidth of entangled photons independently of the frequency band of interest and of the nonlinear crystal. We theoretically show that this technique allows generating nearly transform-limited biphotons with almost one octave of bandwidth hundreds of terahertz which corresponds to correlation times of just a few femtoseconds. The presented method becomes an enabling tool for attosecond entangled-photons quantum optics. The technique can also be used to generate paired photons with a very high degree of entanglement.