Large-scale quantum computers are expected to benefit from modular architectures. Validating the capabilities of modular devices requires benchmarking strategies that assess performance within and between modules. In this work, we evaluate cross-platform verification protocols, which are critical for quantifying how accurately different modules prepare the same quantum state -- a key requirement for modular scalability and system-wide consistency. We demonstrate these algorithms using a six-qubit flip-chip superconducting quantum device consisting of two three-qubit modules on a single carrier chip, with connectivity for intra- and inter-module entanglement. We examine how the resource requirements of protocols relying solely on classical communication between modules scale exponentially with qubit number, and demonstrate that introducing an inter-module two-qubit gate enables sub-exponential scaling in cross-platform verification. This approach reduces the number of repetitions required by a factor of four for three-qubit states, with greater reductions projected for larger and higher-fidelity devices.
@article{arxiv.2507.15302,
title = {Resource-Efficient Cross-Platform Verification with Modular Superconducting Devices},
author = {Kieran Dalton and Johannes Knörzer and Finn Hoehne and Yongxin Song and Alexander Flasby and Dante Colao Zanuz and Mohsen Bahrami Panah and Ilya Besedin and Jean-Claude Besse and Andreas Wallraff},
journal= {arXiv preprint arXiv:2507.15302},
year = {2025}
}