A team of physicists at the University of Oxford has achieved the lowest-ever error rate for a quantum logic operation — just 0.000015%, or one error in 6.7 million operations.
A rendering of the ion trap chip. Image credit: Jochen Wolf & Tom Harty, University of Oxford.
“As far as we are aware, this is the most accurate qubit operation ever recorded anywhere in the world,” said University of Oxford’s Professor David Lucas.
“It is an important step toward building practical quantum computers that can tackle real-world problems.”
To perform useful calculations on a quantum computer, millions of operations will need to be run across many qubits.
This means that if the error rate is too high, the final result of the calculation will be meaningless.
Although error correction can be used to fix mistakes, this comes at the cost of requiring many more qubits.
By reducing the error, the new method reduces the number of qubits required and consequently the cost and size of the quantum computer itself.
“By drastically reducing the chance of error, this work significantly reduces the infrastructure required for error correction, opening the way for future quantum computers to be smaller, faster, and more efficient,” said University of Oxford graduate student Molly Smith.
“Precise control of qubits will also be useful for other quantum technologies such as clocks and quantum sensors.”
This unprecedented level of precision was achieved using a trapped calcium ion as the qubit.
These are a natural choice to store quantum information due to their long lifetime and their robustness.
Unlike the conventional approach, which uses lasers, the researchers controlled the quantum state of the calcium ions using electronic (microwave) signals.
This method offers greater stability than laser control and also has other benefits for building a practical quantum computer.
For instance, electronic control is much cheaper and more robust than lasers, and easier to integrate in ion trapping chips.
Furthermore, the experiment was conducted at room temperature and without magnetic shielding, thus simplifying the technical requirements for a working quantum computer.
“Whilst this record-breaking result marks a major milestone, it is part of a larger challenge,” the authors said.
“Quantum computing requires both single- and two-qubit gates to function together.”
“Currently, two-qubit gates still have significantly higher error rates — around 1 in 2,000 in the best demonstrations to date — so reducing these will be crucial to building fully fault-tolerant quantum machines.”
Their paper was published online in the journal Physical Review Letters.
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M.C. Smith et al. 2025. Single-qubit gates with errors at the 10−7 level. Phys. Rev. Lett, in press; doi: 10.1103/42w2-6ccy
