Lowering Connectivity Requirements For Bivariate Bicycle Codes Using Morphing Circuits

Autor: Shaw, Mackenzie H., Terhal, Barbara M.
Rok vydání: 2024
Předmět:
Druh dokumentu: Working Paper
Popis: Recently, Bravyi et al. [1] proposed a set of small quantum Bivariate Bicycle (BB) codes that achieve a similar circuit-level error rate to the surface code but with an improved encoding rate. In this work, we generalise a novel parity-check circuit design principle that we call morphing circuits (first introduced in [2]) and apply this methodology to BB codes. Our construction generates a new family of BB codes -- including a new $[[144,12,12]]$ "gross" code -- whose parity check circuits require a qubit connectivity of degree five instead of six. Intriguingly, each parity check circuit requires only 6 rounds of CNOT gates -- one fewer than in Ref. [1] -- even though our new codes have weight-9 stabilisers. We also show how to perform logical input/output circuits to an ancillary rotated surface code using morphing circuits, all within a biplanar layout. The new codes perform at least as well as those of Ref. [1] under uniform circuit-level noise when decoded using BP-OSD. Finally, we develop a general framework for designing morphing circuits and present a sufficient condition for its applicability to two-block group algebra codes. [1] S. Bravyi, A. W. Cross, J. M. Gambetta, D. Maslov, P. Rall, and T. J. Yoder, Nature 627, 778 (2024). [2] C. Gidney and C. Jones, New circuits and an open source decoder for the color code (2023), arXiv:2312.08813.
Comment: 29 pages, 14 figures, 9 tables, minor edits to fit journal length requirements
Databáze: arXiv