Sustaining high-fidelity quantum logic in neutral-atom circuits via mid-circuit operations

TL;DR

This paper presents a neutral-atom quantum computing framework that maintains high gate fidelity over deep circuits by integrating mid-circuit operations like cooling and re-initialization, enabling scalable quantum error correction.

Contribution

It introduces a hardware-efficient method combining mid-circuit cooling and qubit re-initialization to sustain high-fidelity gates in neutral-atom quantum circuits.

Findings

Achieved a two-qubit gate fidelity of 99.60%

Maintained ~99.8% fidelity across multiple rounds

Enabled continuous quantum error correction cycles

Abstract

The realization of fault-tolerant quantum computation hinges on the ability to execute deep quantum circuits while maintaining gate fidelities consistently above error-correction thresholds. Although neutral-atom arrays have recently demonstrated high-fidelity two-qubit gates and early-stage logical quantum processors, sustaining such high performance across deep, repetitive circuits remains a formidable challenge due to cumulative motional heating and atom loss. Here we demonstrate a sustainable neutral-atom framework that overcomes these limitations by integrating a suite of hardware-efficient mid-circuit operations. We report a two-qubit controlled logic gate with a raw fidelity of 99.60(1)%, which is further increased to a fidelity of 99.81(1)% via non-destructive erasure detection. Crucially, by implementing in-circuit Raman sideband cooling and qubit re-initialization, we demonstrate that gate fidelities can be maintained at the ~99.8% level across multiple operational rounds without observable degradation. By actively managing the internal and motional entropy of the system mid-stream, our in-situ refreshable architecture provides a critical pathway for executing the repeated syndrome-extraction cycles required for large-scale, continuous quantum error correction.