Researchers at QuTech, working with Fujitsu and Element Six, have reached a significant milestone in quantum computing by demonstrating quantum gates with error rates below 0.1%. This achievement represents a crucial step toward viable large-scale quantum computation.
Quantum computers perform calculations using quantum gates, which must operate with extremely high precision. For quantum error correction to function effectively, these gates must maintain error probabilities below a critical threshold of approximately 0.1-1%. The QuTech team has now successfully met this requirement using diamond spin qubits.
Diamond spin qubits utilize electron and nuclear spins associated with atomic defects in diamond crystal structures. These qubits offer several advantages, including operation at relatively high temperatures (up to 10 Kelvin) and natural compatibility with photons, making them promising candidates for distributed quantum networks. Despite these benefits, achieving the necessary precision with these qubits has been challenging until now.
The researchers demonstrated a complete universal set of quantum gates on a two-qubit system, with each gate operating below the critical 0.1% error threshold. Their most precise gates achieved remarkably low error rates of just 0.001%. To accomplish this, the team used ultrapure diamonds with reduced carbon-13 isotope concentration to minimize noise and designed sophisticated gates that effectively isolate the spin qubits from environmental interference.
A key component of their success was the application of “gate set tomography,” which provided comprehensive quantum descriptions of the gates. This detailed characterization enabled systematic identification and correction of imperfections. The team validated their approach by successfully executing an algorithm requiring 800 consecutive gate operations, demonstrating both the precision and predictability of their system.
While this breakthrough satisfies a critical requirement for quantum computing, significant challenges remain on the path to scalable quantum processors. The QuTech team continues to work on maintaining gate quality while integrating chip-scale optics and electronics for larger qubit systems. This ongoing research represents a collaborative effort between scientific researchers, engineers, and industry partners focused on advancing quantum computing technology.
The research was published in Physical Review Applied on 21 March 2025.
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