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.
@article{arxiv.2102.13293,
title = {Entanglement Across Separate Silicon Dies in a Modular Superconducting Qubit Device},
author = {Alysson Gold and JP Paquette and Anna Stockklauser and Matthew J. Reagor and M. Sohaib Alam and Andrew Bestwick and Nicolas Didier and Ani Nersisyan and Feyza Oruc and Armin Razavi and Ben Scharmann and Eyob A. Sete and Biswajit Sur and Davide Venturelli and Cody James Winkleblack and Filip Wudarski and Mike Harburn and Chad Rigetti},
journal= {arXiv preprint arXiv:2102.13293},
year = {2021}
}