Entanglement across separate silicon dies in a modular superconducting qubit device

Assembling future large-scale quantum computers out of smaller, specialized modules promises to simplify a number of formidable science and engineering challenges. One of the primary challenges in developing a modular architecture is in engineering high fidelity, low-latency quantum interconnects between modules. Here we demonstrate a modular solid state architecture with deterministic inter-module coupling between four physically separate, interchangeable superconducting qubit integrated circuits, achieving two-qubit gate fidelities as high as 99.1 +/- 0.5% and 98.3 +/- 0.3% for iSWAP and CZ entangling gates, respectively. The quality of the inter-module entanglement is further confirmed by a demonstration of Bell-inequality violation for disjoint pairs of entangled qubits across the four separate silicon dies. Having proven out the fundamental building blocks, this work provides the technological foundations for a modular quantum processor: technology which will accelerate near-term experimental efforts and open up new paths to the fault-tolerant era for solid state qubit architectures.

Automated summary

The study demonstrates a modular solid state architecture with deterministic coupling between four physically separate superconducting qubit integrated circuits, achieving high fidelity two-qubit gates. The quality of inter-module entanglement is confirmed, laying the technological foundations for a modular quantum processor.