ETH Zurich achieves 99.91% quantum gate fidelity across 17,000 atom pairs

Thursday 09 April 2026 - 10:05

By: Dakir Madiha

ETH Zurich achieves 99.91% quantum gate fidelity across 17,000 atom pairs

Researchers at ETH Zurich have demonstrated a quantum swap gate with 99.91% fidelity operating simultaneously on over 17,000 pairs of neutral atoms. Published in Nature, the work introduces a gate inherently resistant to common experimental flaws, potentially reshaping paths to large-scale, fault-tolerant quantum computing.

The team, led by Professor Tilman Esslinger and principal investigator Konrad Viebahn, built a two-qubit gate using geometric phases rather than finely tuned dynamic phases typical in most quantum platforms. They trapped potassium-40 fermionic atoms in an optical lattice and created transient "qubit doublon" states where two atoms share a site. Fermionic exchange antisymmetry in these doublons yields a two-particle quantum holonomy free of dynamic phases. This protects the swap operation against laser potential fluctuations and inhomogeneities. Additional resilience stems from time-reversal and chiral symmetries in the underlying Hamiltonian.

This result stands out for its scale. While ion-trap systems like IonQ's 99.99% two-qubit fidelity in October 2025 measured single pairs, ETH Zurich verified 99.91% across the entire 17,000-pair system. This highlights neutral atom platforms' scalability advantages. Combined with the group's prior topological pumping for atom transport, it lays groundwork for highly connected, large-scale quantum processors.

Neutral atom quantum computing gains traction alongside superconducting circuits and trapped ions. These findings address a core challenge: making quantum operations robust enough to scale without impractical environmental controls. Esslinger noted the ability to generate vast numbers of swap gates with neutral atoms. The authors call it a new paradigm turning fundamental symmetries and quantum statistics into resources for fault-tolerant computing.