An on-chip coupled resonator optical waveguide single-photon buffer

摘要

Integrated quantum optical circuits are now seen as one of the most promisingapproaches with which to realize single photon quantum information processing.Many of the core elements for such circuits have been realized includingsources, gates and detectors. However, a significant missing function necessaryfor photonic information processing on-chip is a buffer, where single photonsare stored for a short period of time to facilitate circuit synchronization.Here we report an on-chip single photon buffer based on coupled resonatoroptical waveguides (CROW) consisting of 400 high-Q photonic crystal line defectnanocavities. By using the CROW, a pulsed single photon was successfullybuffered for 150 ps with 50-ps tunability while maintaining its non-classicalproperties. Furthermore, we showed that our buffer preserves entanglement bystoring and retrieving one photon from a time-bin entangled state. This is asignificant step towards an all-optical integrated quantum informationprocessor.