Physicists Break Quantum Barrier with Record-Breaking Qubit Coherence

Their measurement reached the millisecond range, with earlier records topping out at around 0.6 milliseconds, representing a major step forward in quantum computing performance. The findings have just been published in the prestigious peer-reviewed journal Nature Communications.

Achieving longer coherence times means quantum computers can operate reliably for longer periods before errors disrupt computations. This advancement allows more complex operations to be performed on noisy quantum systems and reduces the overhead required for quantum error correction, bringing researchers closer to achieving fault-tolerant quantum computing.

“We have just measured an echo coherence time for a transmon qubit that landed at a millisecond at maximum with a median of half a millisecond,” says Mikko Tuokkola, the PhD student who conducted and analyzed the measurements. The median reading is particularly significant, as it also surpasses current recorded readings.

The researchers report their approach as thoroughly as possible, with the aim of making it reproducible for research groups around the world.

At Aalto University, Tuokkala conducted his work under the guidance of postdoctoral researcher Dr. Yoshiki Sunada, who was responsible for designing the chip and constructing the experimental measurement system.

“We have been able to reproducibly fabricate high-quality transmon qubits. The fact that this can be achieved in a cleanroom which is accessible for academic research is a testament to Finland’s leading position in quantum science and technology,” adds Sunada, who is currently working at Stanford University, USA.

The qubit was fabricated by the QCD group at Aalto using high-quality superconducting film supplied by the Technical Research Centre of Finland (VTT). The success reflects the high quality of Micronova cleanrooms at OtaNano, Finland’s national research infrastructure for micro-, nano-, and quantum technologies.

“This landmark achievement has strengthened Finland’s standing as a global leader in the field, moving the needle forward on what can be made possible with the quantum computers of the future,” says Professor of Quantum Technology Mikko Möttönen, who heads the QCD group.

Scaling up the quantum computers of the future requires advancements across several domains. Among them are noise reduction, qubit-count increases, and the qubit coherence time improvements at the center of the new observations from the QCD. The group just opened a senior staff member and two postdocs positions to achieve future breakthroughs faster.

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