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  • Featured in Physics
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Repeated Ancilla Reuse for Logical Computation on a Neutral Atom Quantum Computer

J. A. Muniz1, D. Crow1, H. Kim1, J. M. Kindem1, W. B. Cairncross1, A. Ryou1, T. C. Bohdanowicz1, C.-A. Chen1, Y. Ji1 et al.

A. M. W. Jones1, E. Megidish1, C. Nishiguchi1, M. Urbanek1, L. Wadleigh1, T. Wilkason1, D. Aasen2, K. Barnes1, J. M. Bello-Rivas2, I. Bloomfield1, G. Booth1, A. Brown1, M. O. Brown1, K. Cassella1, G. Cowan1, J. Epstein1, M. Feldkamp1, C. Griger1, Y. Hassan1, A. Heinz1, E. Halperin1, T. Hofler1, F. Hummel1, M. Jaffe1, E. Kapit1,3, K. Kotru1, J. Lauigan1, J. Marjanovic1, M. Meredith1, M. McDonald1, R. Morshead1, S. Narayanaswami1, K. A. Pawlak1, K. L. Pudenz1, D. Rodríguez Pérez1, P. Sabharwal1, J. Simon4, A. Smull1, M. Sorensen1, D. T. Stack1, M. Stone1, L. Taneja1, R. J. M. van de Veerdonk1, Z. Vendeiro1, R. T. Weverka1, K. White1, T.-Y. Wu1, X. Xie1, E. Zalys-Geller1, X. Zhang1, J. King1, B. J. Bloom1, and M. A. Norcia1

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Phys. Rev. X 15, 041040 – Published 4 December, 2025

DOI: https://doi.org/10.1103/v7ny-fg31

Abstract

Quantum processors based on neutral atoms trapped in arrays of optical tweezers have appealing properties, including relatively easy qubit number scaling and the ability to engineer arbitrary gate connectivity with atom movement. However, these platforms are inherently prone to atom loss, and the ability to replace lost atoms during a quantum computation is an important but previously elusive capability. Here, we demonstrate the ability to measure and reinitialize, and if necessary replace, a subset of atoms while maintaining coherence in other atoms. This allows us to perform logical circuits that include single- and two-qubit gates as well as repeated midcircuit measurement while compensating for atom loss. We highlight this capability by performing up to 41 rounds of syndrome extraction in a repetition code, and combine midcircuit measurement and atom replacement with real-time conditional branching to demonstrate heralded state preparation of a logically encoded Bell state. Finally, we demonstrate the ability to replenish atoms in a tweezer array from an atomic beam while maintaining coherence of existing atoms—a key step toward execution of logical computations that last longer than the lifetime of an atom in the system.

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synopsis

Quantum Computer Recycles Its Atomic Qubits

Published 4 December, 2025

Researchers have developed a protocol for resetting and reloading atoms that are inevitably lost during quantum computations.

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Popular Summary

Neutral atoms are a promising platform for quantum computing because they are identical, can be precisely manipulated with lasers, and interact in highly controllable ways. Arrays of these atoms, held in tightly focused laser beams known as optical tweezers, have enabled demonstrations of logical quantum bits that spread information across several atoms to detect and correct errors. However, a key limitation has been that the ancillary qubits used to check for errors can be heated or lost during measurements. This restricts how long computations can run. In this study, we overcome that challenge by repeatedly measuring and reusing ancilla qubits within quantum circuits while selectively replacing those that are lost, marking a major step toward sustained quantum computation.

We achieve this using a system that integrates atom trapping, measurement, and reloading in a continuous loop. When a trapped atom disappears during a computation, we identify the loss and replace it from a nearby atomic reservoir without disturbing the surrounding qubits. We also perform repeated ancilla measurements to confirm the correct preparation of logical states and demonstrate continuous reloading from a steady atomic source—all while preserving the quantum states of the atoms already in the array. This approach allows the same ancilla qubits to participate in many cycles of error detection and correction.

By enabling the reuse and replenishment of ancilla qubits, we remove a major barrier to scaling up neutral-atom quantum computers. These capabilities make it possible to perform longer and more complex quantum computations and open the door to fault-tolerant logical operations that can outlast any individual qubit.

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Phys. Rev. X 15, 041040– Published 4 December, 2025
  • Received 19 June 2025
  • Accepted 16 October 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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