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arXiv · 2607.07805

Robust Ion-Photon Entanglement via Polarization-to-Time-Bin Conversion

Ana Luiza Ferrari·Denton Wu·Mika A. Zalewski·Norbert M. Linke
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Abstract

Time-bin photonic qubits are well-suited for quantum network applications due to their robustness to polarization instability in fiber links and potential for heterogeneous networks. In this work, we implement the first entanglement-preserving polarization-to-time-bin conversion of a photon qubit in an entangled state with a matter qubit, together with the independent work of Haen \textit{et al.} \cite{haen2026telecom}. Photons initially generated with polarization encoding are converted to the time-bin basis through a polarization-discriminating asymmetric Mach--Zehnder interferometer. The photonic qubits are generated via the $1092$~nm transition of a $^{88}$Sr$^{+}$ ion. We measure state fidelity bounds of $0.906 \pm 0.011 \le \mathcal{F} \le 0.934\pm 0.011$, with conversion error $< 0.028$, and find this fidelity shows no statistically significant reduction under depolarizing noise, even at full depolarization strength.

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Ana Luiza Ferrari, Denton Wu, Mika A. Zalewski, Norbert M. Linke. 2026-07-08. Robust Ion-Photon Entanglement via Polarization-to-Time-Bin Conversion. https://arxiv.org/abs/2607.07805

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