Resource-Efficient Cross-Platform Verification with Modular Superconducting Devices

TL;DR

This paper evaluates cross-platform verification protocols for modular superconducting quantum devices, demonstrating that inter-module gates significantly improve scalability and reduce resource requirements for state verification.

Contribution

It introduces a method to enhance cross-platform verification scalability using inter-module gates, reducing resource needs compared to classical communication-only protocols.

Findings

Inter-module gates enable sub-exponential scaling in verification

Resource requirements are reduced by a factor of four for three-qubit states

Scalability improves with higher-fidelity devices

Abstract

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.