ETH Zurich Researchers Achieve Stability Breakthrough in Quantum Computing Using Geometric Phases

Researchers at ETH Zurich use geometric phases to create robust swap gates for neutral atom quantum computers, enabling 99.91% precision across 17,000 qubit pairs.

By: AXL Media

Published: Apr 8, 2026, 11:41 AM EDT

Source: Information for this report was sourced from EurekAlert!

Overcoming the Fragility of Neutral Atom Qubits

While superconducting circuits and trapped ions have dominated quantum computing headlines, neutral atoms trapped in laser light offer a distinct advantage: they lack electric charge, making them less susceptible to external environmental disturbances. However, neutral atoms face a significant hurdle in the stability of their logic operations, or "quantum gates." Traditional methods relying on the tunnel effect or atomic collisions are notoriously sensitive to even microscopic fluctuations in laser intensity. To address this, a team at ETH Zurich led by Professor Tilman Esslinger has introduced a geometric phase approach that fundamentally changes how quantum information is exchanged.

The Power of Geometric over Dynamical Phases

In quantum mechanics, gates are typically executed using dynamical phases, which are influenced by how particles interact or move through space. These are highly dependent on the precision of the experimental setup. In contrast, geometric phases are more abstract; they depend on the path a particle takes rather than external noise or the speed of manipulation. By trapping ultra-cold potassium atoms in optical lattices, the ETH team manipulated laser beams to bring atom pairs so close that their wavefunctions overlapped. Because the potassium atoms are fermions—particles that cannot occupy the exact same state—this manipulation naturally generated a geometric phase that is inherently robust against experimental noise.

Massive Scalability: 17,000 Qubits at Once

One of the most significant hurdles in quantum computing is scaling a system to handle thousands of qubits. The ETH Zurich researchers demonstrated that their geometric swap gate—which exchanges the states of two qubits—could be applied to several thousand qubits simultaneously. In their experiment, they successfully executed the gate for 17,000 qubit pairs with a precision of 99.91%. This level of accuracy, achieved in less than a millisecond, marks a major step toward practical, large-scale quantum computers that can operate reliably without being derailed by minor laser "flickers."