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Five silicon qubits, one control wire, 99.9% accuracy at once.

RIKEN researchers found the hidden error that appears when qubits share wiring, and calibrated it away. The work is published in Nature Physics.

ZN ZilverNet EditorialPublished · 3 min read · 3 sources Announced Oct 16, 2026
False-color micrograph of the five-qubit silicon device, qubits Q1 to Q5 marked in a row
Cropped from Fig. 1a of the paper; licensed CC BY 4.0. Wu, Camenzind et al., Nature Physics (2026).
The short versionResearch
What it is
Five silicon spin qubits operated at the same time through one shared microwave control line.
The result
Single operations "well above 99.99%" accurate; above 99.99% with up to three qubits at once; about 99.9% with all five.
Why it matters
Scaling up means running many qubits from shared wiring. Doing that without losing accuracy is the hard part.
Still limited
The remaining error comes from drive-induced decoherence.

The problem

Every qubit in a quantum computer needs to be controlled, and giving each one its own wiring doesn't scale. Sharing a control line is the obvious fix, but driving several qubits at once introduces errors that don't appear when you operate them one at a time.

A team at RIKEN's Center for Emergent Matter Science traced the main source of that extra error to the AC Stark shift, and corrected for it.

The fix

The researchers developed a pairwise calibration method. Individual operations reached "well above 99.99%" accuracy, with the best approaching 99.999%. Running up to three qubits simultaneously stayed above 99.99%; all five together reached about 99.9%.

"This shows that high-fidelity control can be maintained even when several qubits are operated at the same time." — Leon Camenzind, RIKEN

What's left is drive-induced decoherence. "This is a limitation, but further improvements to device design could help mitigate this source of error," Camenzind said.

The goal

The work is part of Japan's Moonshot Goal 6 program. "Our long-term goal is to build a fault-tolerant quantum computer based on silicon spin qubits," said project manager Seigo Tarucha.

Sources

  1. A path toward larger quantum processors — RIKEN · Oct 16, 2026
  2. Scientists overcome a hidden obstacle to more powerful quantum computers — ScienceDaily, republishing RIKEN · Oct 25, 2026
  3. Simultaneous high-fidelity single-qubit gates in a spin qubit array — Nature Physics, 2026 — Wu, Camenzind, … Tarucha
Update log
  • Published.