Small Structures On Large Scales

Scientists at the University of Paderborn research quantum networks

So-called optical quantum networks form the basis for future technologies such as the quantum computer or the quantum internet. One challenge in the implementation of such networks has so far been the need to interconnect many components in a large system. Scientists at the University of Paderborn want to overcome this hurdle as part of the research project "Qinos" (quantum components - integrated, optical, scalable) with the help of thin layers of lithium niobate. The aim is to develop a simple integrated quantum network that should demonstrate the basic functionality of large networks. The project will be funded by the Federal Ministry of Education and Research (BMBF) for two years from September with around 1.9 million euros.

Thin-film lithium niobate (LNOI) is a very promising candidate for quantum applications: “It enables previously impossible functionalities such as fast electro-optical switches or highly efficient photon pair sources. Photons are small light particles that make up electromagnetic radiation, ”explains Dr. Christof Eigner, who is the project leader in the group for integrated quantum optics of Leibniz Prize winner Prof. Dr. Christine Silberhorn has taken over. With the material LNOI, the scientists are developing a novel, scalable approach to combine a large number of functional elements. “The outstanding properties of lithium niobate are already used very often in the telecommunications industry, for example. However, conventional lithium niobate components reach their limits, especially with regard to the integration density, i.e. the maximum number of sources and switches that can be combined on one component. LNOI addresses precisely these weaknesses. In this way, high-precision structures can be transferred to substrates using lithography. In this way, complex quantum circuits with high application potential can be implemented that cannot be implemented in this form on other material platforms, ”continues Eigner.

The physicists are developing a network in which an integrated photon pair source is combined with an integrated wavelength-selective beam splitter. The photons are generated by laser light. The pairs are then separated and made available for end use in different exits. Eigner: "With this we show the efficient generation of quantum light and the routing, so to speak the control of photons in a quantum network."

On the basis of the results achieved in the project, multifunctional, application-oriented quantum components could be implemented in the future and interconnected to form large, complex networks. In addition, through the involvement of industrial partners, the entire value chain for photonic quantum hardware is to be brought into industrial application. The team expects the first results as early as next year.

The BMBF supports the project as part of the “Quantum Technologies - From Basics to Market” funding program (funding number 13N15975).