Reconfigurable quantum networks of superconducting qubit devices

Modular quantum networks are a promising path for scaling quantum processors.  A critical concern for their implementation is presented by lossy connections between modules that lead to low-efficiency inter-module gates.  In this talk, I will present our efforts for realizing high-fidelity gates, entanglement distribution, and protection of distributed quantum information in superconducting qubit networks realized with cable-based interconnects.  The performance of our network depends on our connecting architecture and control of the inter-module interactions.  The separated qubits are capacitively coupled to a coaxial cable, which can be reconfigured through low-loss detachable connections.  Inter-module gates are controlled by microwave pumps applied on the qubits.  Combining these approaches has enabled us to realize fast, high-fidelity SWAP gates through a coaxial cable bus [1], as well as stabilized, remote entanglement through a directional waveguide [2].  Going forward, this architecture will allow us to build toward other features needed for a scalable network.  The simplicity of our connections has the potential for all-to-all connectivity of multiple modules through a single coaxial cable. Ancillary qubits will enable us to detect communication errors in the form of erasures. Together, these features present a compelling path for modular, error-protected scaling of superconducting quantum processors.

[1]. Mollenhauer, M., Irfan, A., Cao, X. et al. Nat Electron 8, 610–619 (2025). https://doi.org/10.1038/s41928-025-01404-3.

[2]. Irfan, A. et al., Preprint at https://doi.org/10.48550/arXiv.2509.11872 (2025).