Research and Development

The primarily goal of the project A is to develop system designs for scalable quantum repeaters and establish their requirements. Although a number of repeater protocols have been proposed and some experimentally realized, there has been little attention paid to the development of overall system designs for quantum repeater.  In such system development, devices need to be integrated in a scalable manner, and at the same time, the system imposes conditions on devices themselves. The system and device are two essential elements for any scalable quantum information systems.  Figure 1 schematically illustrates these technology layers from the bottom physics layer to the top architecture layer.  These three layers are rather independent in their constructions, nonetheless are required to work together as one system.  The total structure as well as the efficiency of each element will significantly affect the networks overall performance.

Technological layers in quantum repeater design

Fig. 1Technological layers in quantum repeater design.

In the previous NICT repeater project, an initial quantum repeater system design was developed.  Figure 2 shows the entanglement distribution protocol for this design. This new design significantly improved the overall network performance (much faster communication rates). Furthermore it demonstrated by example that commonly believed device requirements can be dramatically changed by system design for the better. It decreased the quantum repeater memory/storage times by a factor of 1000. The new project A takes this repeater design as its starting point, and applies/develops it to repeater architecture and system designs applicable to small to large distance quantum communication. Scalability and feasibility are the most important parameters in this development, being a driving force to push the fundamental research towards the future development of practical quantum repeater systems.

A new entanglement distribution scheme. It has been shown that this scheme can be integrated into efficient repeater design.

Fig. 2A new entanglement distribution scheme. It has been shown that this scheme can be integrated into efficient repeater design.

Future prospective:

This overall research project focuses on the development of devices and systems for quantum repeater and networks.   Initially these will very relevant for extending the distance quantum keys can be distributed - beyond the 100km distance currently achievable but more importantly will open possibilities for combining quantum devices with classical telecommunications. In the medium to long term this repeater will form the backbone of a quantum network and the future quantum internet. The core devices developed will also become a core technology for general quantum information processing (distributed quantum computation for instance).