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arXiv · 2512.17779

Demonstration of a quantum comparator on an ion-trap quantum device

Tatsuhiko N. Ikeda·Riku Nakama·Shunsuke Saeki·Hiroki Kuwata·Shuhei M. Yoshida·Akira Shimizu·Sho Sugiura
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Abstract

Quantum computers are believed to solve a class of computational problems that are based on modular arithmetic faster than classical computers. Among the arithmetic building blocks, comparison of integer pairs is a primitive. Here we report its demonstration in the Reimei quantum computer at RIKEN, whose trapped-ion architecture provides all-to-all qubit connectivity together with high gate fidelities. We observe high success probabilities for bit widths n = 3, 5, 7, and 9: Under a conventional output-only success criterion we obtain 95% at n=9; under a stricter criterion additionally requiring the ancilla to be correct, the success is 69% at n=9. These results demonstrate reliable quantum comparison at scales far beyond those previously achieved experimentally, not only for comparators but also in the broader context of quantum arithmetic circuits.

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Tatsuhiko N. Ikeda, Riku Nakama, Shunsuke Saeki, Hiroki Kuwata, Shuhei M. Yoshida, Akira Shimizu, Sho Sugiura. 2025-12-19. Demonstration of a quantum comparator on an ion-trap quantum device. https://arxiv.org/abs/2512.17779

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