Entanglement Across Separate Silicon Dies in a Modular Superconducting Qubit Device

TL;DR

This paper demonstrates a modular superconducting qubit architecture with high-fidelity inter-module entanglement across separate silicon dies, advancing scalable quantum computing technology.

Contribution

It introduces a modular solid-state quantum architecture with deterministic inter-module coupling and high-fidelity entanglement between separate silicon dies.

Findings

Achieved two-qubit gate fidelities up to 99.1% and 98.3%.

Confirmed inter-module entanglement via Bell inequality violation.

Established foundational technology for modular quantum processors.

Abstract

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$\pm0.5$\% and 98.3$\pm$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.