Heterogeneous Quantum Networking Using Photonic Chips

We report on the design, fabrication, and testing of an integrated photonic chip aimed at overcoming bottlenecks in trapped ion quantum networks. Current bulk optics limit the entanglement rate to a single photonic link of order ≃100 sec-1. To address this, we use a parallelized architecture where light is simultaneously collected from multiple ions in a chain, dramatically increasing the entanglement rate between modules. The use of fiber arrays, with order 100 micron pitch, makes mode matching arrays of ions challenging while maintaining efficient light collection. We address this through a custom fabricated photonic circuit that efficiently collects light from a chain of Barium Ions using a high NA lens objective. The chip integrates mode matching inverse tapers, polarization management devices, optical switches for routing, and 50/50 beam splitters. Further, we include on-chip frequency conversion schemes for facilitating hybrid networking between differing qubit species. Our integrated approach provides a scalable route toward high speed, general purpose quantum networking.