Inside Cat Qubits Physics, Implementation, and the Road to Fault Tolerance - Roberto Negrin

Negrin, Roberto

Published Nov 13, 2025• 0 citations

Abstract

Alice & Bob is a quantum computing company based in Paris and Boston aiming to build the first universal, fault-tolerant quantum computer. Founded in 2020, the company has raised €130M, grown to 150+ employees, and reported experimental results surpassing those of larger incumbents. Advised by Nobel Prize–winning researchers, Alice & Bob specializes in cat qubits, a technology pioneered by its founders and later adopted by Amazon, which can reduce the hardware needed for a useful large-scale quantum computer by up to 200× compared with competing approaches. This talk introduces cat qubits, quantum bits built from two well-separated states of a nonlinear superconducting resonator, and shows how their built-in stability enables hardware-efficient error correction. It will explain, at a high level, how cat qubits work, why they can reduce the number of qubits needed for useful algorithms, and what this means for reaching fault tolerant quantum computing. We’ll also touch on real progress, the benefits, and the key challenges ahead

DOI: 10.5281/zenodo.17693098

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