Repeated ancilla reuse for logical computation on a neutral atom quantum computer

TL;DR

This paper demonstrates repeated ancilla atom reuse, measurement, and replacement in neutral atom quantum computers, enabling longer logical computations despite atom loss.

Contribution

It introduces techniques for measuring, re-initializing, and replacing atoms during quantum circuits, enhancing the robustness of neutral atom quantum processors.

Findings

Performed up to 41 rounds of syndrome extraction in a repetition code.

Achieved heralded state preparation of a logical Bell state with midcircuit measurement.

Replenished atoms from an atomic beam while maintaining coherence.

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 re-initialize, 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 towards execution of logical computations that last longer than the lifetime of an atom in the system.