Realization of an Error-Correcting Surface Code with Superconducting Qubits

TL;DR

This paper reports the first experimental realization of a repeated error-correcting surface code on superconducting qubits, demonstrating significant logical error reduction and advancing towards scalable fault-tolerant quantum computing.

Contribution

It experimentally implements a distance-3 surface code with 17 qubits, achieving repeated error correction cycles on a superconducting quantum processor.

Findings

Logical error rate is significantly reduced after correction.

First experimental demonstration of repeated surface code error correction.

Progress towards 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.