A superconducting qutrit link beyond the qubit limit
Abstract
Superconducting microwave links have enabled deterministic state transfer and remote entanglement between qubits, but deterministic links have so far operated with an effectively two-dimensional transmitted Hilbert space. Here we demonstrate a superconducting qutrit link between two independently packaged nodes connected by a microwave channel. Each node combines a transmon qutrit, a transmission resonator, and a tunable Purcell-filter interface, allowing the two remote microwave-photon interfaces to be matched in both frequency and bandwidth. We implement two transition-selective photon-mediated operations that transfer the |e⟩ and |f⟩ qutrit components in distinct temporal modes of the same channel. We tomographically characterize arbitrary qutrit-state transfer, obtaining a mean transferred-state fidelity of 83.68% and a qutrit process fidelity of 77.12%, exceeding both the classical qutrit-transfer benchmark and the best possible average fidelity of an effective qubit channel used to transmit an arbitrary qutrit. Using partial-transfer operations, we reconstruct a remote two-qutrit state with negativity 0.730, a tomography-inferred dense-coding capacity of 2.273 bits, and a tomography-inferred Collins-Gisin-Linden-Massar-Popescu (CGLMP) parameter I3=2.332, all beyond the corresponding qubit or local bounds. These results demonstrate a superconducting microwave link that uses the native three-level structure of transmons as a genuine high-dimensional communication resource.
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BibTeX
@misc{li2026superconducting,
title = {{A superconducting qutrit link beyond the qubit limit}},
author = {Xiang Li and Zheng-Yang Mei and Yang He and Si-Lu Zhao and Yan-Jun Liu and Xiao-Hui Song and Kai Xu and Zhong-Cheng Xiang and Dong-Ning Zheng and Heng Fan},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2606.29475},
eprint = {2606.29475},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.29475},
}
RIS
TY - UNPB
TI - A superconducting qutrit link beyond the qubit limit
AU - Xiang Li
AU - Zheng-Yang Mei
AU - Yang He
AU - Si-Lu Zhao
AU - Yan-Jun Liu
AU - Xiao-Hui Song
AU - Kai Xu
AU - Zhong-Cheng Xiang
AU - Dong-Ning Zheng
AU - Heng Fan
PY - 2026
DA - 2026/10/04
PB - arXiv
DO - 10.48550/arxiv.2606.29475
UR - https://arxiv.org/abs/2606.29475
AB - Superconducting microwave links have enabled deterministic state transfer and remote entanglement between qubits, but deterministic links have so far operated with an effectively two-dimensional transmitted Hilbert space. Here we demonstrate a superconducting qutrit link between two independently packaged nodes connected by a microwave channel. Each node combines a transmon qutrit, a transmission resonator, and a tunable Purcell-filter interface, allowing the two remote microwave-photon interfaces to be matched in both frequency and bandwidth. We implement two transition-selective photon-mediated operations that transfer the |e⟩ and |f⟩ qutrit components in distinct temporal modes of the same channel. We tomographically characterize arbitrary qutrit-state transfer, obtaining a mean transferred-state fidelity of 83.68% and a qutrit process fidelity of 77.12%, exceeding both the classical qutrit-transfer benchmark and the best possible average fidelity of an effective qubit channel used to transmit an arbitrary qutrit. Using partial-transfer operations, we reconstruct a remote two-qutrit state with negativity 0.730, a tomography-inferred dense-coding capacity of 2.273 bits, and a tomography-inferred Collins-Gisin-Linden-Massar-Popescu (CGLMP) parameter I_3=2.332, all beyond the corresponding qubit or local bounds. These results demonstrate a superconducting microwave link that uses the native three-level structure of transmons as a genuine high-dimensional communication resource.
ER -