Alice & Bob decodes LDPC-cat error correction codes on GPUs via NVIDIA NVQLink

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French cat qubit company Alice & Bob says it is the first to decode its LDPC-cat error correction codes on GPUs using NVIDIA's NVQLink architecture. Quantum Zeitgeist covered the announcement, which is based on a press release. Decoding is the classical work of reading error signals from a quantum chip and working out how to fix them, and it has to happen very quickly

The team used NVQLink to connect a Quantum Machines OPX1000 controller and its Open Acceleration Stack to GPUs. The round trip latency was in the microsecond range, which is the kind of speed real time error correction needs. The goal was to test whether GPU decoding is a practical option for this type of code

Some background helps here. LDPC-cat codes were set out in a January 2025 paper about low overhead quantum computing in two dimensions. They combine cat qubits, which naturally resist one type of error, with efficient LDPC codes to handle the rest. In March 2026, Alice & Bob decoded simulated syndrome data on NVIDIA's CUDA-Q in just under two hours

The new result is a proof of concept, and the company is clear about its limits. It still uses synthetic data rather than signals from a real chip, and it does not yet run in real time. The team is now speeding up the pipeline that moves measurement data to the GPU and believes processing syndromes in parallel could help close the gap

Statements came from Sam Stanwyck of NVIDIA and Juliette Peyronnet of Alice & Bob. NVIDIA has been building partnerships across the quantum industry, and decoding is a natural fit for GPUs. Each step like this makes fault tolerant machines feel a little more concrete

Do you think GPUs will become the standard way to decode quantum error correction? And how close are cat qubits to a real fault tolerant demonstration?

Alice & Bob Decodes LDPC-cat Codes On GPUs With NVIDIA NVQLinkquantumzeitgeist.com