Long range connectivity in a scalable superconducting qubit network

Qubit connectivity plays a pivotal role in the performance of a quantum processor by minimizing the gate count for an arbitrary multi-qubit operation. However, most superconducting quantum processors exhibit only nearest neighbor coupling. Hence the quantum information may require to be transferred across several qubits to perform an arbitrary operation resulting in reduced fidelity due to finite coherence of the qubits.
Our novel design is based on a ring resonator as a single coupling element between several qubits distributed around the ring’s circumference. This enables long range connectivity between qubits while maintaining physical separation between them, leading to negligible qubit cross-talk. We theoretically analyse the relative inter-qubit coupling strength and experimentally verify it in a device capable of supporting up to twelve qubits where each qubit can be connected to nine other qubits. We also discuss how to extend the design to a larger number of qubits. Our design is planar, scalable and does not require complex fabrication involving crossovers. Moreover, this is adaptable to any qubit type and gate-scheme that uses a bus resonator for multiqubit interaction and thus versatile in its applicability.