Realization of an Error-Correcting Surface Code with Superconducting Qubits

TLDR

Quantum error correction, essential for moving from NISQ devices to fault‑tolerant quantum computers, relies on the surface code—a high‑threshold, two‑dimensional grid code whose repeated error‑correction capability has yet to be experimentally demonstrated. The study aims to experimentally implement a distance‑3 surface code comprising 17 qubits on the Zuchongzhi 2.1 superconducting quantum processor. The authors realize the code by arranging 17 qubits on the Zuchongzhi 2.1 processor and performing repeated error‑correction cycles. Executing multiple consecutive error‑correction cycles reduced logical errors, demonstrating the surface code’s repeated error‑correction capability for the first time and establishing a fully functional instance that advances scalable fault‑tolerant quantum computing.

Abstract

Quantum error correction is a critical technique for transitioning from noisy intermediate-scale quantum (NISQ) devices to fully fledged quantum computers. The surface code, which has a high threshold error rate, is the leading quantum error correction code for two-dimensional grid architecture. So far, the repeated error correction capability of the surface code has not been realized experimentally. Here, we experimentally implement an error-correcting surface code, the distance-3 surface code which consists of 17 qubits, on the \textit{Zuchongzhi} 2.1 superconducting quantum processor. By executing several consecutive error correction cycles, the logical error can be significantly reduced after applying corrections, achieving the repeated error correction of surface code for the first time. This experiment represents a fully functional instance of an error-correcting surface code, providing a key step on the path towards scalable fault-tolerant quantum computing.