Spectral compression and frequency shifts of single photons by cascade modulation

Spectral manipulation of single photons as an essential quantum technology provides a feasible method for highly efficient quantum interconnects between quantum systems with different transition linewidths via flying photons, which expands the capabilities of quantum networks. In this Letter, we propose a scalable scheme based on side-end cavity and time-dependent phase modulation, which allows the spectral compression of single photons by hundreds of times and even more, with an efficiency higher than active spectrum filtering. In addition, the achievable frequency shifts of single photons can reach hundreds of gigahertz. These techniques allow the implementation of a high-efficiency quantum interface between single photons and atomic quantum memories, as well as high-visibility quantum interference between two independent single photons. Our scheme opens up a way for hybrid quantum networks involving quantum systems with different transition linewidths.