Quantum-Correlation-Preserving Single-Photon Conversion by Molecular Modulation in Gas-filled Hollow-Core Fibres

Preservation of the photon statistics of quantum states of light upon frequency conversion is of great importance for modern quantum optics. For example, it holds the key to practical implementation of systems such as quantum networks which often require interfacing of different sub-units that do not operate in the same frequency bands. Although many integrated schemes have been demonstrated [1] , [2] , most offer small frequency shifts, limited tunability, and often suffer from high insertion loss and Raman noise generated in bulk materials.