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arXiv:2502.14859 · PRX Quantum

Taming the Recoil Effect in Cavity-Assisted Quantum Interconnects

Seigo Kikura, Ryotaro Inoue, Hayata Yamasaki, Akihisa Goban, Shinichi Sunami

Published Oct 23, 2025• 6 citations
arXivHTMLPDF

Abstract

Photon recoil is one of the fundamental limitations for high-fidelity control of trapped-atom qubits such as neutral atoms and trapped ions. In this work, we derive an analytical model for efficiently evaluating the motion-induced infidelity in remote entanglement generation protocols. Our model is applicable for various photonic qubit encodings, such as polarization, time-bin, and frequency encodings, and with arbitrary initial motional states, thus providing a crucial theoretical tool for realizing high-fidelity quantum networking. For the case of tweezer-trapped neutral atoms, our results indicate that operation in the with cavity decay rate exceeding the atom-photon coupling rate and near-ground-state cooling with motional quanta below 1 are desired to suppress the motion-induced infidelity sufficiently below the 1% level required for efficient quantum networking. Finite-temperature effects can be mitigated efficiently by detection time filtering at the moderate cost of success probability and network speed. These results extend the understanding of infidelity sources in remote entanglement generation protocols, establishing a concrete path toward fault-tolerant quantum networking with scalable trapped-atom qubit systems.

DOI
10.1103/njh8-q7gb

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Abstract Photonic interconnects between quantum processing nodes are likely the only way to achieve large-scale quantum computers and networks (1). The bottleneck in such an architecture is the interface between well-isolated quantum memories and flying photons. We establish high-fidelity entanglement between remotely separated trapped atomic qubit memories (2–4), mediated by photonic qubits stored in the timing of their pulses (5). Such time-bin encoding removes sensitivity to polarization errors, enables long-distance quantum communication, and is extensible to quantum memories with more than two states. Using a measurementbased error detection process and suppressing a fundamental source of error due to atomic recoil, we achieve an entanglement fidelity of 97% and show that fidelities beyond 99.9% are feasible.
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Quantum links between physically separated modules are important for scaling many quantum computing technologies. The key metrics are the generation rate and fidelity of remote Bell pairs. In this work, we propose an experimental protocol for generating remote entanglement between neutral ytterbium atom qubits using an optical cavity. By loading a large number of atoms into a single cavity, and controlling their coupling using only local light shifts, we amortize the cost of transporting and initializing atoms over many entanglement attempts, maximizing the entanglement generation rate. A twisted ring cavity geometry suppresses many sources of error, allowing high-fidelity entanglement generation. We estimate a spin-photon entanglement rate of 5 × 10 5 s − 1 , and a Bell pair rate approaching 10 5 s − 1 , with an average fidelity near 0.999 . Furthermore, we show that the photon detection times provide a significant amount of soft information about the location of errors, which may be used to improve the logical qubit performance. This approach provides a practical path to scalable modular quantum computing using neutral ytterbium atoms. Published by the American Physical Society 2024