Volumetric Fiber-to-Chip Mode Converters (C55-4b)

As progress in quantum information and computation leads to various ground-breaking technologies, there is a need for developing protocols to integrate systems to form quantum networks. The largest bottleneck for quantum networking is optical loss, which reduces quantum information fidelity and occurs at the component and system- level interconnects. Developing ultra-low loss interconnects is critical for realizing quantum networks in the near term. To solve the challenge of ultra-low-loss optical interconnects, this program will develop a standard fiber to photonic chip connector based on gray-scale 3D printing. As more quantum technologies take advantage of photonic and electronic integrated circuits, we require techniques for efficiently extracting light off chip and into long-distance fibers that connect the network. Our gray-scale lithography approach provides the best control of connector geometries, optical interfaces, and refractive indices of any technology and thus will allow us to achieve the lowest optical losses and develop swappable design that are customized for different quantum platforms. In Phase I, we will leverage our ongoing work developing chip-based quantum technologies and 3D gray-scale printing to create ultra-low loss connectors between entangled-photon sources, quantum encoding and routing devices, and optical fibers. Combined, these elements comprise the foundation for implementing a quantum network. We will design, fabricate, and evaluate prototype connectors to demonstrate our capability. Phase I will target connecting two devices with < 1 dB connection loss, which will pave the way for a Phase II effort that will target tens of devices with < 0.5 dB loss at each interconnect. Our mode-converter technology will enable ultra-low loss optical interconnects between integrated chips and current fiber-based networks, greatly increasing the capacity of near-term quantum networks without the bottleneck of optical loss limiting the network scale. This approach will reduce infrastructure requirements to expedite development of some of the first quantum networks. These devices will become key components for every node within a quantum network, which will enable advanced quantum computing, secure communication, and distributed quantum sensing. Note that low-loss interconnects could also have a major role in classical telecommunications as well, increasing system efficiency and bandwidth.