Quantum error correction with silicon spin qubits.

Future large-scale quantum computers will rely on quantum error correction (QEC) to protect the fragile quantum information during computation 1,2 . Among the possible candidate platforms for realizing quantum computing devices, the compatibility with mature nanofabrication technologies of silicon-based spin qubits offers promise to overcome the challenges in scaling up device sizes from the prototypes of today to large-scale computers 3-5 . Recent advances in silicon-based qubits have enabled the implementations of high-quality one-qubit and two-qubit systems 6-8 . However, the demonstration of QEC, which requires three or more coupled qubits 1 , and involves a three-qubit gate 9-11 or measurement-based feedback, remains an open challenge. Here we demonstrate a three-qubit phase-correcting code in silicon, in which an encoded three-qubit state is protected against any phase-flip error on one of the three qubits. The correction to this encoded state is performed by a three-qubit conditional rotation, which we implement by an efficient single-step resonantly driven iToffoli gate. As expected, the error correction mitigates the errors owing to one-qubit phase-flip, as well as the intrinsic dephasing mainly owing to quasi-static phase noise. These results show successful implementation of QEC and the potential of a silicon-based platform for large-scale quantum computing.