A modular approach to superconducting quantum information processing

Modular architectures for quantum computing present an interesting alternative to the popular monolithic approach. This is especially true for solid-state based computing such as with superconducting qubits: Assembling a quantum processor from small pre-selected modules promises higher average performance qubits with fewer drop-outs, as well as offering the opportunity to shield modules from one another, reducing cross-talk and increasing the available frequency span within each module. Protection from cosmic-ray-like events may also be possible. Challenges in modular architectures include designing circuits that can accommodate the unavoidably smaller interconnect densities between modules, with the concomitant challenge of preserving error-protection functionality. In this talk I will describe our approach to a modular superconducting quantum processor, using an assembly of separate qubit daughterboards interconnected via a router-supported motherboard, in which externally controlled routers selectively couple qubits on daughterboards flip-chip coupled to the motherboard. The routers support multi-qubit entangling operations, controlled using model-free reinforcement learning, including two-qubit controlled-Z gates as well as three-qubit controlled-swap gates. If time permits, I will also describe recent measurements of cosmic-ray-like events in these assemblies.^1,2

1 See also closely related contributed talks from our group, including by Xuntao Wu et al. and Yash Joshi et al.

2 X. Wu^a, G. Andersson^a, A. Anferov^a, C. R. Conner^a, Y. J. Joshi^a, A. M. King^a, S. Li^b, H. L. Malc^a, J. M. Miller^b, H. Mishra^a, H. Qiao^a, M. Ryu^a, J. Shi^c, ^aPritzker School of Molecular Engineering, University of Chicago, Chicago IL 60637; ^bPhysics, University of Chicago, Chicago IL 60637; Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180