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arXiv:2512.05037 · Physical Review Research

Expanding the Neutral Atom Gate Set: Native iSWAP and Exchange Gates from Dipolar Rydberg Interactions

Pedro Ildefonso, Andrew Byun, Aleksei Konovalov, Javad Kazemi, Michael Schuler, Wolfgang Lechner

quant-phSubmitted Dec 4, 2025• Announced Dec 5, 2025• 0 citations
v1 · Dec 4, 2025v2 · Jun 24, 2026v3 · Sep 7, 2026
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Abstract

We present a native realization of iSWAP and parameterized exchange gates for neutral atom quantum processing units. Our approach leverages strong dipole-dipole interactions between two dipole-coupled Rydberg states, and employs optimal control techniques to design time-efficient, high-fidelity gate protocols. To minimize experimental complexity, we utilize global driving terms acting identically on all atoms. We implement a noise-aware pulse selection strategy to identify candidate protocols with reduced susceptibility to certain noise sources, then analyze their performance under realistic noise sources -- including atomic motion, Rydberg decay, and experimentally motivated laser phase and intensity noise. For a $^{88}$Sr-based architecture, we demonstrate fast iSWAP gate protocols which exceed fidelities of $99.9\%$ under realistic experimental conditions. These results pave the way for expanding the neutral atom gate set beyond typical Rydberg blockade-based entangling gates.

Journal reference
Ildefonso, P., Byun, A., Konovalov, A., Kazemi, J., Schuler, M., & Lechner, W. (2026). Expanding the neutral-atom gate set: Native iSWAP and exchange gates from dipolar Rydberg interactions. Physical Review Research, 8(3), 033269
DOI
10.1103/z46h-mgh4
Comments
15 pages, 8 figures (plus appendix)

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We present a native realization of iSWAP and parameterized exchange gates for neutral atom quantum processing units. Our approach leverages strong dipole-dipole interactions between two dipole-coupled Rydberg states, and employs optimal control techniques to design time-efficient, high-fidelity gate protocols. To minimize experimental complexity, we utilize global driving terms acting identically on all atoms. We implement a noise-aware pulse selection strategy to identify candidate protocols with reduced susceptibility to certain noise sources, then analyze their performance under realistic noise sources -- including atomic motion, Rydberg decay, and experimentally motivated laser phase and intensity noise. For a 88^{88}88Sr-based architecture, we demonstrate fast iSWAP gate protocols which exceed fidelities of 99.9%99.9\%99.9% under realistic experimental conditions. These results pave the way for expanding the neutral atom gate set beyond typical Rydberg blockade-based entangling gates.
We present a theoretical scheme for a family of fast and high-fidelity two-qubit iSWAP gates between neutral atoms separated by more than 20 um, enabled by resonant dipole-dipole spin-exchange interactions between Rydberg states. The protocol harnesses coherent excitation-exchange-deexcitation dynamics between the qubit and the Rydberg states within a single and smooth laser pulse, in the presence of strong dipole-dipole interactions. We utilize optimal control methods to achieve theoretical gate fidelities and durations comparable to blockade-based gates in the presence of relevant noise, while extending the effective interaction range by an order of magnitude. This enables entanglement well beyond the blockade radius, offering a route toward fast, high-connectivity quantum processors.
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The advent of digital neutral-atom quantum computers relies on the development of fast and robust protocols for high-fidelity quantum operations. In this work, we introduce a novel scheme for entangling gates using four atomic levels per atom: a ground-state qubit and two Rydberg states. A laser field couples the qubit to one of the two Rydberg states, while a microwave field drives transitions between the two Rydberg states, enabling a resonant dipole-dipole interaction between different atoms. We show that controlled- Z gates can be realized in this scheme without requiring optical phase modulation and relying solely on a microwave field with time-dependent phase and amplitude. We demonstrate that such gates are faster and less sensitive to Rydberg decay than state-of-the-art Rydberg gates based on van der Waals interactions. Moreover, we systematically stabilize our protocol against interatomic distance fluctuations and analyze its performance in realistic setups with rubidium or cesium atoms. Our results open up new avenues to the use of microwave-driven dipolar interactions for quantum computation with neutral atoms.
Rydberg blockaded gate is a fundamental ingredient for scalable quantum computation with neutral Rydberg atoms. However the fidelity of such a gate is intrinsically limited by a blockade error coming from a Rydberg level shift that forbids its extensive use. Based on a dark-state adiabatic passage, we develop a novel protocol for realizing a two-atom blockade-error-free quantum gate in a hybrid system with simultaneous van der Waals (vdWsI) and resonant dipole-dipole interactions (DDI). The basic idea relies on converting the roles of two interactions, which is, the DDI serves as one time-dependent tunable pulse and the vdWsI acts as a negligible middle level shift, as long as the adiabatic condition is preserved. We adopt an optimized super-Gaussian optical pulse with kπ(k ≫ 1) area accompanied by a smooth tuning for the DDI, composing a circular stimulated Raman adiabatic passage, which can robustly ensure a faster operation time ∼ 80ns as well as a highly-efficient gate fidelity ∼ 0.9996. This theoretical protocol offers a flexible treatment for hybrid interactions in complex Rydberg systems, enabling on-demand design of new types of effective Rydberg quantum gate devices.
We present a native approach for realizing multiqubit parity phase gates in neutral-atom systems through global phase modulation of a Rydberg excitation laser. By shaping the temporal profile of the laser’s phase, we enable high-fidelity, time efficient entangling operations between multiple qubits without requiring individual qubit addressing. To mitigate intrinsic noise sources including spontaneous decay and motional effects, we develop a noise-aware optimal control framework that reduces gate errors under the presence of noise while maintaining smooth pulse profiles suitable for experimental implementation. In addition to equidistant qubit arrangements, we explore the impact of nonequidistant atomic configurations, where interaction inhomogeneity becomes significant. In these cases, the flexibility of our control approach helps to compensate for such variations, supporting reliable gate performance across different spatial layouts. These results facilitate the practical implementation of complex, multiqubit quantum operations in near-term neutral-atom quantum processors.
Abstract Rydberg quantum gate serving as an indispensable computing unit for neutral-atom quantum computation, has attracted intense research efforts for the last decade. However, the state-of-the-art experiments have not reached the high gate fidelity as predicted by most theories due to the unexpected large loss remaining in Rydberg and intermediate states. In this paper, we report our findings in constructing a native two-qubit controlled-NOT gate based on pulse optimization. We focus on the method of commonly-used two-photon Rydberg excitation with smooth Gaussian-shaped pulses which is straightforward for experimental demonstration. By utilizing optimized pulse shapes the scheme reveals a remarkable reduction in the decays from Rydberg and intermediate states, as well as a high-tolerance to the residual thermal motion of atoms. We extract a conservative lower bound for the gate fidelity >0.9921 after taking into account the experimental imperfections. Our results not only reduce the gap between experimental and theoretical prediction because of the optimal control, but also facilitate the connectivity of distant atomic qubits in a larger atom array by reducing the requirement of strong blockade, which is promising for developing multiqubit quantum computation in large-scale atomic arrays.