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

Neutral-atom quantum processing units scale to large qubit numbers, yet their native entangling gate set is largely limited to diagonal Rydberg-blockade gates [1, 2]. We present a native implementation of non-diagonal iSWAP and arbitrary-angle exchange gates [3] by exploiting strong dipole–dipole exchange between two distinct, dipole-coupled Rydberg states, moving beyond the usual van der Waals regime. Using quantum optimal control [4], we design time-efficient, high-fidelity protocols while keeping experimental overhead low by restricting to global driving fields that address both atoms identically. A noise-aware pulse selection step identifies candidates with reduced sensitivity to dominant errors, followed by benchmarking under realistic conditions for a state-of-the-art ⁸⁸Sr architecture, including atomic motion, Rydberg decay, and laser phase/intensity noise modeled via realistic power spectral densities [5]. We find fast iSWAP protocols exceeding 99.9% fidelity with currently achievable parameters. These native exchange gates complement Controlled-Z operations, enabling shorter circuits and longer-range entanglement for algorithms and quantum error correction schemes that benefit from iSWAP dynamics, e.g., dynamical surface codes [6] and Parity-based circuits [7].

References:

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  [2] R. Finkelstein, at al., Nature 634, 321 (2024).

  [3] D. M. Abrams, et al., Nature Electronics 3, 744 (2020).

  [4] N. Khaneja, et al., Journal of Magnetic Resonance 172, 296 (2005).

  [5] R. B.-S. Tsai, et al., PRX Quantum 6, 010331 (2025).

  [6] A. Eickbusch, et al., Nature Physics 10.1038/s41567-025-03070-w (2025).

  [7] M. Drieb-Schön, et al., Quantum 7, 951 (2023).