Alice & Bob reports the first implementation of LDPC-cat codes decoded on GPUs using NVIDIA’s NVQLink architecture, a key step toward scalable error correction for its cat-qubit quantum computers. Alice & Bob assessed the feasibility of GPU decoding for LDPC-cat codes using an NVQLink connection with Quantum Machines’ OPX1000 and Open Acceleration Stack, a modular framework that couples the controller directly to GPUs.
“Error correction is what will turn quantum computers into useful machines, and decoding is one of its most demanding classical tasks,” said Juliette Peyronnet, US GM Alice & Bob. Researchers also demonstrated that multiple syndromes can be decoded in parallel, suggesting a path toward faster processing even though real-time decoding remains a goal.
LDPC-cat Code Decoding Feasibility on NVIDIA NVQLink Architecture
The first demonstration of LDPC-cat code decoding on graphics processing units (GPUs) via NVIDIA’s NVQLink architecture confirms a key step toward scalable quantum error correction. This connection enabled the assessment of GPU decoding feasibility for the company’s LDPC-cat codes, initially detailed in their January 2025 publication, “LDPC-cat codes for low-overhead quantum computing in 2D”.
The team is now focused on optimizing the data pipeline, the sequence of steps moving measurement data through NVQLink to the GPU, to achieve the performance necessary for real-time error correction, NVIDIA says. NVIDIA’s NVQLink architecture proved instrumental in this initial demonstration, providing the low-latency, high-throughput connection needed to accelerate the decoding process.
Sam Stanwyck, Director, Quantum Product at NVIDIA, explained that a major challenge with present day quantum computing is errors build up faster than they can be corrected, and traditionally it has been a challenge to bring compute to this problem for faster qubit modalities like cat qubits. He further stated that Alice and Bob’s work shows how NVQLink can accelerate the real-time decoding needed to turn cat qubits into fault tolerant quantum-GPU supercomputers.
This collaboration extends a pre-existing relationship between the two companies, including a March 2026 announcement of a one hour 57 minute runtime for decoding simulated syndrome data using the NVIDIA CUDA-Q platform. The successful demonstration of GPU-accelerated decoding for LDPC-cat codes represents a shift in how error correction capacity can scale. Peyronnet emphasized that this means decoding capacity can grow with the machine, a significant advantage as quantum computers increase in complexity.
Alice & Bob’s approach to error correction uses cat qubits, a technology developed by the company’s founders, and this latest work builds on their previous findings showing a potential reduction of up to 200 times in hardware requirements for large-scale quantum computers compared to alternative methods. The company will continue to refine the system, aiming to bridge the gap between the current proof-of-concept and the demands of real-time quantum computation.
Error correction is what will turn quantum computers into useful machines, and decoding is one of its most demanding classical tasks. Showing that our LDPC-cat codes can be decoded on NVIDIA GPUs with existing tools is encouraging for scaling, because it means decoding capacity can grow with the machine. The next step is making it fast enough to keep pace with the quantum computer, and we’re working with NVIDIA to get there.
Juliette Peyronnet, US GM Alice & Bob
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