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arXiv · 2511.17460

Improved error correction with leakage reduction units built into qubit measurement in a superconducting quantum processor

Yuejie Xin·Sean L. M. van der Meer·Marc Serra-Peralta·Tim H. F. Vroomans·Matvey Finkel·Hendrik M. Veen·Mark W. Beekman·Leonardo DiCarlo
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Abstract

Leakage to non-computational states is a source of correlated errors in both time and space that limits the effectiveness of quantum error correction (QEC) with superconducting circuits. We present and experimentally demonstrate a high-fidelity, leakage reduction unit (LRU) operating concurrently with transmon measurement without incurring time overhead. Adapted from double-drive reset of population (DDROP), the protocol utilizes simultaneous drives on the transmon and its readout resonator, leveraging the dispersive shift to create a directional process that returns the transmon to the computational subspace. The LRU achieves a 98.4% leakage removal fraction without compromising the computational-state assignment fidelity (99.2%). We combine LRU-enhanced measurement and neural-network decoding to successfully suppress logical error rates in both memory and stability QEC experiments without any post-selection.

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Yuejie Xin, Sean L. M. van der Meer, Marc Serra-Peralta, Tim H. F. Vroomans, Matvey Finkel, Hendrik M. Veen, Mark W. Beekman, Leonardo DiCarlo. 2025-11-21. Improved error correction with leakage reduction units built into qubit measurement in a superconducting quantum processor. https://arxiv.org/abs/2511.17460

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