Enhancing Connectivity in Superconducting Qubit Systems with an On-Chip Quantum Router Design*

Connectivity plays a crucial role in the design of modular quantum systems and the development of large-scale distributed quantum computing and error correction architectures. Superconducting qubits, a leading platform for fault-tolerant quantum computing, face limitations in their connectivity, typically allowing connections to only a few neighboring qubits. Achieving higher connectivity typically often involves complex multi-layer packaging or relayed state transfer, which can be resource-intensive and limited in fidelity. Here, we propose an innovative on-chip quantum router design that facilitates long-range all-to-all connectivity and boasts a high on-off ratio. We will show experimental results for the transfer of quantum states between arbitrary qubit pairs and fidelity measurements in two-qubit gate operations mediated by the coupler pairs. This approach opens up promising possibilities for efficiently engineering couplings within large-scale quantum computers, and offers a pathway for implementing quantum algorithms and error correction schemes that benefit from enhanced qubit connectivity.