LEGO: QEC Decoding System Architecture for Dynamic Circuits

TL;DR

LEGO is a flexible quantum error correction decoding architecture designed to support dynamic logical circuits, enabling reconfiguration and integration of innovations to advance fault-tolerant quantum computing.

Contribution

The paper introduces LEGO, a novel QEC decoder architecture with decoding blocks that support dynamic circuits and improve efficiency, accuracy, and reconfigurability.

Findings

Supports all QEC settings with easy reconfiguration

Enhances decoding efficiency through parallelism and pipelining

Facilitates innovation in quantum hardware and logical operations

Abstract

Quantum error correction (QEC) is a critical component of FTQC; the QEC decoder is an important part of Classical Computing for Quantum or C4Q. Recent years have seen fast development in real-time QEC decoders. Existing efforts to build real-time decoders have yet to achieve a critical milestone: decoding dynamic logical circuits with error-corrected readout and feed forward. Achieving this requires significant engineering effort to adapt and reconfigure the decoders during runtime, depending on the branching of the logical circuit. We present a QEC decoder architecture called LEGO, with the ambitious goal of supporting dynamic logical operations. LEGO employs a novel abstraction called the decoding block to describe the decoding problem of a dynamic logical circuit. Moreover, decoding blocks can be combined with three other ideas to improve the efficiency, accuracy and latency of the decoder. First, they provide data and task parallelisms when combined with fusion-based decoding. Second, they can exploit the pipeline parallelism inside multi-stage decoders. Finally, they serve as basic units of work for computational resource management. Using decoding blocks, LEGO can be easily reconfigured to support all QEC settings and to easily accommodate innovations in three interdependent fields: code, logical operations and qubit hardware. In contrast, existing decoders are highly specialized to a specific QEC setting, which leads to redundant research and engineering efforts, slows down innovation, and further fragments the nascent quantum computing industry.