Alice & Bob

Alice & Bob describes its mission as building the first universal, fault-tolerant quantum computer. The company specializes in cat qubits, a technology developed by its founders, which it presents as a qubit with built-in protection against errors: cat qubits suppress bit-flip errors in hardware, so error correction only has to handle phase flips. Its website names Helium as a testbed for error correction and links this work to a roadmap toward early fault-tolerant quantum computing for high-performance computing.

Founded in 2020 and based in Paris and Boston, the company says it has raised €180 million and employs more than 250 people, and that it is advised by Nobel Prize-winning researchers. In October 2026 its researchers published a resource estimate on the IACR ePrint archive concluding that a cat-qubit machine using LDPC-cat codes could factor RSA-2048 with 22,593 physical qubits in 3.14 days, which the company presents as a record low for total quantum resources needed to run Shor's algorithm.