Quantum low-density parity-check (qLDPC) codes have emerged as a compelling route to scalable, fault-tolerant quantum computation and communication with dramatically reduced overheads compared to surface-code architectures. In this talk, I will present a unified perspective on recent advances in high-rate qLDPC coding and their implications for large-scale quantum computation. First, we show how high-rate qLDPC codes can be implemented on realistic hardware platforms such as reconfigurable neutral atom arrays [1, 5]. We then explore universal operations enabled by high-rate, high-distance qLDPC codes [3, 4]. In particular, finite-block-length "tricycle" codes support constant-depth logical CCZ gates across three code blocks, enabling direct magic-state generation and single-shot error correction with logical error rates on the order of 10^(-10). This achieves full universality without the large overheads of conventional magic-state distillation. We further introduce new neural decoders for qLDPC codes [6]. Applied to bivariate bicycle codes, these decoders reach the highest logical accuracies reported to date, exhibiting no observed error floors down to very low logical error rates - addressing a long-standing limitation of machine-learning-based decoders. Finally, we extend qLDPC techniques to distributed quantum computing [2] and conclude with a discussion of the challenges and opportunities for realizing practical high-rate qLDPC quantum architectures.
*We acknowledge financial support from IARPA and the Army Research Office, under the Entangled Logical Qubits program (Cooperative Agreement Number W911NF-23-2-0219), the DARPA MeasQuIT program (grant number HR0011-24-9-0359), the Center for Ultracold Atoms (a NSF Physics Frontiers Center, PHY-1734011), the National Science Foundation (grant numbers PHY-2012023 and CCF-2313084).
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Publication:[1] Q. Xu*, JPBA*, C. A. Pattison, N. Raveendran, D. Bluvstein, J. Wurtz, B. Vasic, M. D. Lukin, L. Jiang, H. Zhou, "Constant-Overhead Fault-Tolerant Quantum Computation with Reconfigurable Atom Arrays" (Nature Physics 2024) [2] JPBA, H. Zhou, Q. Xu, G. Baranes, B. Li, M. D. Lukin, L. Jiang, "Constant-Overhead Fault-Tolerant Bell-Pair Distillation using High-Rate Codes" (PRL 2025) [3] Q. Xu, H. Zhou, G. Zheng, D. Bluvstein, JPBA, M. D. Lukin, L. Jiang, "Fast and Parallelizable Logical Computation with Homological Product Codes", (PRX 2025) [4] V. Menon*, JPBA*, R. Mehta, A. Gu, D. B. Tan, M. D. Lukin, "Magic tricycles: Efficient magic state generation with finite block-length quantum LDPC codes" (arXiv 2025) [5] D. B. Tan, JPBA, V. Menon, J. M. Koh, A. C. Diaconu, M. D. Lukin, "Syndrome Extraction Circuits with Near-Optimal Depths for Practical Quantum Error Correcting Code Families" (In preparation) [6] A. Gu, JPBA, et al. "Scaling Neural Decoders to Large Codes and Low Error Rates" (In preparation)
Presenters
J. Pablo Bonilla Ataides
Harvard
Authors
J. Pablo Bonilla Ataides
Harvard
Varun Menon
Harvard
Andi Gu
Harvard
Qian Xu
Caltech
California Institute of Technology
Christopher Pattison
Caltech
Daniel B Tan
Harvard University
Harvard
Hengyun Zhou
QuEra Computing Inc.
QuEra Computing Inc., Massachusetts Institute of Technology