Quantum computers are alternative computing devices that process information, leveraging quantum mechanical effects, such as entanglement between different particles. Entanglement establishes a link between particles that allows them to share states in such a way that measuring one particle instantly affects the others, irrespective of the distance between them.
Quantum computers could, in principle, outperform classical computers in some optimization and computational tasks. However, they are also known to be highly sensitive to environmental disturbances (i.e., noise), which can cause quantum errors and adversely affect computations.
Researchers at the International Quantum Academy, Southern University of Science and Technology, and Hefei National Laboratory have developed a new approach to detect these errors in a silicon-based quantum processor. This error detection strategy, presented in a paper published in Nature Electronics, was found to successfully detect quantum errors in silicon qubits, while also preserving entanglement after their detection.
“In this work, we used the nuclear spins of phosphorus donors in a silicon cluster to encode quantum information, with the atomic-scale device functioning as a quantum information processor,” Prof. Yu He, co-senior author of the paper, told Phys.org.
“What drives and inspires us is the broader dream of quantum computing itself. For quantum computers to become truly practical, they must achieve fault tolerance—and that means the challenges along the way must first be identified and addressed.”
High-fidelity error detection via stabilizer measurements
Over the past few decades, quantum engineers have introduced a broad range of approaches designed to improve the reliability of quantum computer processors, with the goal of enabling their fault-tolerant operation. Building on earlier works, Prof. He and his colleagues set out to develop a new strategy to achieve high-fidelity quantum error detection, which relies on so-called stabilizer measurements.
Stabilizers are mathematical rules that describe the properties that a correct quantum state should have. If a quantum processor is operating correctly and did not make any errors, stabilizer measurements would thus be aligned with these mathematical rules. In contrast, a stabilizer measurement that differs from predictions would suggest that an error has occurred.
“To realize stabilizers for quantum error detection, we need quantum circuits capable of high-fidelity, quantum-nondemolition (QND) readout of errors,” explained Prof. He.
“To this end, we employed a circuit with minimal resource demands: two qubits encode the quantum information, while two additional ancilla qubits are used for stabilizer readout. The circuit design leverages the fully connected donor cluster, which makes circuit compilation relatively straightforward, and nuclear spins, which enable high-fidelity QND readout—and, in turn, high-fidelity error detection via stabilizers.”
To assess their approach, the researchers created a small silicon-based quantum processor that consists of four entangled nuclear spin qubits and one electron spin qubit. The four nuclear spins in the system were highly entangled, via a so-called four-qubit Greenberger-Horne-Zeilinger (GHZ) state.
The researchers implemented their stabilizer-based error detection approach onto this small processor, with the aim of detecting all possible types of errors affecting individual qubits. This also allowed them to shed light on what errors were most prevalent in their silicon-based quantum computing system.
Towards scalable and reliable quantum computers
In the team’s initial tests, their proposed error detection strategy was found to successfully detect errors at a single-qubit level without causing decoherence and a consequent loss of information. In the future, their approach could be improved further and tested on other processors with a greater number of underlying qubits.
“We demonstrated that a silicon spin qubit system can perform quantum error detection using stabilizers, establishing a key pillar of fault-tolerant quantum computation,” said Prof. He.
“Importantly, our circuit also revealed the presence of biased noise—although an expected feature whose direct detection via stabilizers is also very exciting. This finding suggests that the system can leverage such biased noise, enabling relaxed thresholds in quantum error correction and making scaling toward a fault-tolerant quantum computer more feasible.”
The recent efforts by Prof. He and his colleagues could contribute to the future advancement of quantum technologies and could help to move existing processors closer to fault-tolerant operation. Meanwhile, the researchers are working on the development of new quantum processors that perform well on specific types of computational tasks.
“Our next goal is to build a minimal logical quantum processor—capable of preparing logical states, implementing universal logical quantum gates, and demonstrating simple logical algorithms—thereby advancing the field into the realm of logical quantum computing,” added Prof. He.
“Together with the present work, this would represent a significant step forward for fault-tolerant quantum computing.” Quantum computers are alternative computing devices that process information, leveraging quantum mechanical effects, such as entanglement between different particles. Entanglement establishes a link between particles that allows them to share states in such a way that measuring one particle instantly affects the others, irrespective of the distance between them.
Quantum computers could, in principle, outperform classical computers in some optimization and computational tasks. However, they are also known to be highly sensitive to environmental disturbances (i.e., noise), which can cause quantum errors and adversely affect computations.
Researchers at the International Quantum Academy, Southern University of Science and Technology, and Hefei National Laboratory have developed a new approach to detect these errors in a silicon-based quantum processor. This error detection strategy, presented in a paper published in Nature Electronics, was found to successfully detect quantum errors in silicon qubits, while also preserving entanglement after their detection.
“In this work, we used the nuclear spins of phosphorus donors in a silicon cluster to encode quantum information, with the atomic-scale device functioning as a quantum information processor,” Prof. Yu He, co-senior author of the paper, told Phys.org.
“What drives and inspires us is the broader dream of quantum computing itself. For quantum computers to become truly practical, they must achieve fault tolerance—and that means the challenges along the way must first be identified and addressed.”
High-fidelity error detection via stabilizer measurements
Over the past few decades, quantum engineers have introduced a broad range of approaches designed to improve the reliability of quantum computer processors, with the goal of enabling their fault-tolerant operation. Building on earlier works, Prof. He and his colleagues set out to develop a new strategy to achieve high-fidelity quantum error detection, which relies on so-called stabilizer measurements.
Stabilizers are mathematical rules that describe the properties that a correct quantum state should have. If a quantum processor is operating correctly and did not make any errors, stabilizer measurements would thus be aligned with these mathematical rules. In contrast, a stabilizer measurement that differs from predictions would suggest that an error has occurred.
“To realize stabilizers for quantum error detection, we need quantum circuits capable of high-fidelity, quantum-nondemolition (QND) readout of errors,” explained Prof. He.
“To this end, we employed a circuit with minimal resource demands: two qubits encode the quantum information, while two additional ancilla qubits are used for stabilizer readout. The circuit design leverages the fully connected donor cluster, which makes circuit compilation relatively straightforward, and nuclear spins, which enable high-fidelity QND readout—and, in turn, high-fidelity error detection via stabilizers.”
.
To assess their approach, the researchers created a small silicon-based quantum processor that consists of four entangled nuclear spin qubits and one electron spin qubit. The four nuclear spins in the system were highly entangled, via a so-called four-qubit Greenberger-Horne-Zeilinger (GHZ) state.
The researchers implemented their stabilizer-based error detection approach onto this small processor, with the aim of detecting all possible types of errors affecting individual qubits. This also allowed them to shed light on what errors were most prevalent in their silicon-based quantum computing system.
Towards scalable and reliable quantum computers
In the team’s initial tests, their proposed error detection strategy was found to successfully detect errors at a single-qubit level without causing decoherence and a consequent loss of information. In the future, their approach could be improved further and tested on other processors with a greater number of underlying qubits.
“We demonstrated that a silicon spin qubit system can perform quantum error detection using stabilizers, establishing a key pillar of fault-tolerant quantum computation,” said Prof. He.
“Importantly, our circuit also revealed the presence of biased noise—although an expected feature whose direct detection via stabilizers is also very exciting. This finding suggests that the system can leverage such biased noise, enabling relaxed thresholds in quantum error correction and making scaling toward a fault-tolerant quantum computer more feasible.”
The recent efforts by Prof. He and his colleagues could contribute to the future advancement of quantum technologies and could help to move existing processors closer to fault-tolerant operation. Meanwhile, the researchers are working on the development of new quantum processors that perform well on specific types of computational tasks.
“Our next goal is to build a minimal logical quantum processor—capable of preparing logical states, implementing universal logical quantum gates, and demonstrating simple logical algorithms—thereby advancing the field into the realm of logical quantum computing,” added Prof. He.
“Together with the present work, this would represent a significant step forward for fault-tolerant quantum computing.” https://phys.org/news/2026-02-silicon-quantum-processor-qubit-errors.html
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