InQuoSens – Thuringian Innovation Center for Quantum Optics and Sensing

Addressing optics for optical quantum computers.

Image: Fraunhofer IOF Jena

Photonic Integrated Circuits (PICs) will be able to realize the same or even improved functionalities as discrete optical elements on optical chips, just as discrete electrical circuits were integrated on chips in the 20th century. In addition, it is already clear that PICs will be extremely important components in future 5G/6G communication systems due to their energy efficiency and climate friendliness. Programmable PICs, which often consist of cascaded Mach-Zehnder interferometers, are becoming increasingly important for emerging applications such as photonic quantum information processing, quantum-enhanced sensors, optical neural networks and machine learning due to their compact dimensions, high computing speed, low power consumption, good scalability and high phase stability. These new applications place high demands on photonic integration on a very large scale and on the performance parameters of the diverse on-chip components to be integrated, such as optical modulators with extremely low losses, ultra-high switching speeds up to the GHz range and high power efficiency.

Building on this state of the art, InQuoSens has identified PICs for quantum technologies, i.e. Quantum Photonic Integrated Circuits (Q-PICs), as an extremely attractive next innovation leap. Compared to “normal” PICs, Q-PICs have some fundamental requirements, the technological implementation of which involves some major challenges. For example, the realization of quantum information processes requires complete integration in the quantum system while preserving the quantum information in a qubit system or the coupling of different qubit systems with minimal losses.

Therefore, all components and functionalities for quantum information processing must be integrated. Based on the correspondingly expanded technology platforms, Q-PICs open the door to the new application areas of 2nd generation quantum technologies. They will be able to address enormously wide wavelength ranges and at the same time, just like classic electronic chips, have immense scaling potential for later production in large quantities for volume applications. However, since Q-PICs require nonlinear and active elements, they cannot be manufactured from established materials such as pure silicon. Rather, Q-PICs require the integration of several functional layers and materials on the wafer scale. The Innovation Center InQuoSens is taking on exactly this challenge.