A Qubit That Stayed in Tune for Three Months express

Original: "Absence of Charge Offset Drift in a Transmon Qubit"

· Adria Rospars, Hector Hutin, Yannick Seis, Cristóbal Lledó, Réouven Assouly, Romain Cazali, Rémy Dassonneville, Ambroise Peugeot, Alexandre Blais, Audrey Bienfait, Benjamin Huard

arXiv:2603.12367 · 2026-03-12 · CC BY 4.0 · 1 min

Quantum Physics Mesoscale Materials

A random layer on a chip held charge at zero, and pointed the way to stable quantum circuits.

A quantum computer is like an orchestra where every musician must hit their note without going flat. But superconducting qubits share a common ailment: random charges accumulate on their electrodes, and the 'note' drifts. Engineers call this charge offset drift, and usually battle it for years.

In the new study, a tantalum qubit held its tuning for nearly three months: the charge stayed pinned at zero, even though the device was warmed to room temperature and cooled again twice. Then, on the next cooldown, the stability vanished — a sign that the mechanism was fragile. The answer lay on the surface: during fabrication, a thin superconducting layer remained between the electrodes, acting as an extra inductance and preventing the charge from wandering.

The layer formed because tantalum was incompletely etched on sapphire — a manufacturing flaw that turned out to be useful.

Now engineers want to make such a layer on purpose. If they succeed, qubits will stop 'going out of tune' from random charges, and quantum circuits will become simpler and more reliable.

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Tantalum is a refractory metal used in smartphone capacitors; here, it helped a qubit hold its tuning.

Scientists

David Deutsch Erwin Schrödinger John Stewart Bell Louis de Broglie Lov Grover Paul Benioff

Concepts

transmon qubit transmon josephson current charge qubit zero resistance Josephson effect superconducting electronics critical current superconducting wire micrometer effect superconductivity aluminum oxide charge transfer transition temperature semimetal triplet superconductivity conduction electron quantum superfluidity semiconductor qubits conductor lithium ion

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A Qubit That Stayed in Tune for Three Months express