December 29, 2025 by Paul Arnold, Phys.org
Collected at: https://phys.org/news/2025-12-microwave-pulses-leaks-quantum-reliable.html
Scientists have developed a new approach to correcting common quantum computing errors, which could pave the way for more reliable systems.
Quantum computers are powerful, primarily experimental machines that use the principles of quantum mechanics to solve complex problems much faster than today’s fastest supercomputers. But they are not perfect yet.
The leakage problem
The fundamental units of information in these systems (qubits) are incredibly delicate. Unlike the bits of conventional computers, which have only two values (0 or 1), quantum bits can exist in a combination of states simultaneously, but this property makes them prone to errors such as leakage. This is where a qubit suddenly jumps to a higher energy level, moving out of its operational state, which stops it from being part of the calculation. It also interferes with the other qubits around it.
In a new study published in Physical Review Letters, scientists have revealed a way to plug these leaks before they accumulate and crash the system.
One of the most common ways to deal with errors in quantum computers is with a process called Quantum Error Correction (QEC). However, some QEC operations and the hardware itself can also introduce leakage. Another approach is to shift a qubit’s frequency, but this requires additional hardware that is difficult and complex to scale up.
Jian-Wei Pan at the University of Science and Technology of China and his colleagues have developed a new way to fix these errors by nudging the leaking qubits back to their correct energy levels with microwave pulses.
The team tested their method on a custom-built Zuchongzhi 3.2 processor with an array of 97 qubits, including data qubits (which hold the quantum information for the calculation) and ancilla qubits (helpers for detecting and correcting errors).
Mopping up the leaks
The researchers intentionally induced leakage by pushing qubits into higher energy levels. Then they fired microwave pulses to remove the error from the data qubits, allowing them to return to their computational state without the calculation being disturbed.
At the same time, they reset the ancilla qubits with another microwave pulse to fully clear the error. Overall, this method mopped up leakage errors over 70 times more effectively than running the system without leakage suppression.
This approach was tested on small and large sections of the array. The results showed that the larger the system, the more reliable the quantum computer became. In other words, if you add more qubits, the error rate goes down. This is considered one of the holy grails of quantum computing. Before this experiment, adding more qubits usually made the problem worse.
“Our results demonstrate the viability of all-microwave control architectures for suppressing critical errors at scale, paving the way for more advanced quantum error correction implementations,” write the researchers in their paper.
More information: Tan He et al, Experimental Quantum Error Correction below the Surface Code Threshold via All-Microwave Leakage Suppression, Physical Review Letters (2025). DOI: 10.1103/rqkg-dw31
Journal information: Physical Review Letters
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