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Fast Entangling Gates for Rydberg Atoms via Resonant Dipole-Dipole Interaction

Giuliano Giudici1,2,3,*, Stefano Veroni3, Giacomo Giudice3, Hannes Pichler1,2, and Johannes Zeiher4,5,6

  • *Contact author: giuliano.giudici@uibk.ac.at
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PRX Quantum 6, 030308 – Published 17 July, 2025

DOI: https://doi.org/10.1103/5d8p-3hm1

Abstract

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.

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Popular Summary

Accurate and high-speed quantum operations are essential building blocks for realizing useful quantum computers. Among various hardware platforms, neutral atoms have emerged as a promising candidate because of their remarkable scalability to large arrays with thousands of highly coherent qubits and the capability for atom rearrangement during computation. However, creating precise and controllable quantum operations that entangle pairs of qubits remains a key challenge. This work introduces a method that improves speed and simplifies control in realizing two-qubit gates, paving the way for scalable and robust quantum processors.

The presented protocol makes use of Rydberg atoms, neutral atoms excited to high-lying electronic states, which can interact strongly over long distances. Whereas traditional gate schemes rely on van der Waals interactions between Rydberg states, this approach employs a resonant dipole-dipole interaction between two distinct Rydberg levels, controlled through a combination of laser and microwave fields. A key benefit is the elimination of real-time optical phase control, typically required in conventional gate protocols. In addition, the method achieves a 20% speedup in gate execution compared with the state of the art, thus pushing the fundamental limit on achievable fidelity set by Rydberg decay. The protocol is also robust to fluctuations in atomic spacing and performs well under realistic experimental conditions using rubidium or cesium atoms.

These results demonstrate that microwave-driven dipolar interactions are a powerful tool for neutral-atom quantum computing. By improving both speed and control, the method developed in this work offers a promising path toward enhancing the precision of quantum logic operations.

Article Text

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Outline

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PRX Quantum 6, 030308– Published 17 July, 2025
  • Received 19 January 2025
  • Revised 22 April 2025
  • Accepted 5 June 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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