Periodic Reporting for period 1 - IQARO (Integrated Quantum Repeater Nodes)
Período documentado: 2024-04-01 hasta 2026-03-31
Recent breakthroughs in the field of quantum technologies combining academic and R&D efforts have demonstrated the potential of quantum networks for major applications such as long-distance secure communication or quantum cloud computing. One current challenge is to deploy quantum networks out of the lab for realizing their expected far-reaching societal and economic impact. A crucial requirement for reaching this goal is the realization of a quantum repeater that will be able to extend quantum links to continental distances. In this context, the use of integrated photonic platforms, allowing for low-footprint, alignment-free and mass-manufacturable quantum nodes, represents a significant resource for real-life applications of quantum networks. In this proposal, we provide a route for achieving this goal through the integration of rare-earth quantum memories on fiber-pigtailed glass photonic chips.
Over the course of this MSCA PF project, several important advances have been made towards this objective. Firstly, we benchmarked our approach on a bulk rare-earth doped crystal quantum memory by showing dual-rail quantum storage of single photons and synchronous readout of single photons from independent spatial modes. Beyond the scope of this project, they represent significant steps towards the implementation of quantum repeater links with this platform. Secondly, building on the reported achievements on a bulk system, we proceeded to extend them to the integrated architecture that is the core subject of this proposal. Our partners at IFN Milan managed to build a hybrid photonic chip featuring a dual rail quantum memory with reconfigurable interferometer at the input and output. With this device, we showed dual-rail storage in the classical regime as well as interference of the retrieved light fields using the tuneable phase shifters.
The preliminary results achieved using the bulk sample are an important contribution to the demonstration of elementary quantum repeater links with rare-earth quantum memories, currently one of the most promising systems for this purpose. Indeed, the demonstration of dual-rail storage in the quantum regime and the capacity to enhance the four-fold coincidence rate of two independent photon sources using quantum memories are important milestones. Moreover, the results on the integrated device are deeply innovative since this hybrid photonic chip architecture is the first reported to date combining light storage and reconfigurable addressing of independent spatial modes, two essential functionalities of quantum network nodes.