Alice & Bob: How Cat Qubits Are Rewriting the Rules of Fault-Tolerant Quantum Computing
- Ramesh Manikondu
- 7 days ago
- 3 min read
In the global race toward universal quantum computing, one of the most formidable bottlenecks has been hardware overhead. Traditional superconducting quantum processors, such as those relying on standard transmons, require up to 1,000 physical qubits to build a single error-corrected logical qubit. Founded in 2020 by Théau Peronnin (CEO) and Raphaël Lescanne (CTO) as a spinoff from École Normale Supérieure (ENS) and Inria, Paris-based deep-tech pioneer Alice & Bob is taking a fundamentally different hardware approach. By leveraging cat qubits a specialized type of noise-biased superconducting qubit Alice & Bob autonomously suppresses bit-flip errors at the physical layer, reducing the hardware resources required for fault tolerance by up to 200 times.
Executive Overview
Company Name: Alice & Bob
Sector: Quantum Computing Hardware
Core Technology: Superconducting Cat Qubits & Bosonic Quantum Codes
Headquarters: Paris, France (with US offices in Boston, MA)
Founders: Dr. Théau Peronnin (CEO) and Dr. Raphaël Lescanne (CTO)
Team Size: 200+ employees
Funding & Financial Backing
Alice & Bob has raised over €130 million ($148 million+) across multiple equity rounds and non-dilutive government grants:
Series B Round (January 2025): Secured $100 million (€100M) in Series B funding led by AXA Venture Partners, Bpifrance (via the Large Venture fund), Future French Champions, Breega, and Elaia Partners.
Deep Tech Innovation Grant (March 2024): Awarded a €17.9 million ($19.5M) grant from Bpifrance under the France 2030 plan to accelerate cat qubit hardware scaling.
Series A Round (March 2022): Raised €30 million ($33M) led by Elaia Partners and Supernova Invest.
Breakthrough Achievements
World Record Bit-Flip Stability (>1 Hour): In late 2025, Alice & Bob demonstrated bit-flip lifetimes ranging between 33 and 60+ minutes on its Galvanic Cat architecture (Helium 2 chip). This shattered their previous record of 7 minutes on the Boson 4 chip and outperformed conventional transmon qubits by orders of magnitude.
200x Hardware Efficiency Gain: By solving bit-flips autonomously at the hardware level, cat qubits require error correction only for phase-flips. This reduces physical-to-logical qubit ratios from thousands down to fewer than 30 physical qubits per logical unit.
Launch of the Helium Quantum System (2026): Alice & Bob unveiled Helium, their first full turn-key quantum system built for on-premise installation in High-Performance Computing (HPC) centers. Operating at a compact 40 kW power envelope, Helium encodes logical qubits with just 18 cat qubits and includes native integration with Slurm schedulers and the custom Starboard monitoring UI.
Demonstration of Controlled-NOT Gates (CNOT): Demonstrated the first two-qubit CNOT gate operating natively between protected cat qubits on the Hydrogen experimental processor.
Research Status & Scientific Innovations
Alice & Bob works at the intersection of nonlinear quantum optics, superconducting microwave circuits, and fault-tolerant architectural design:
Asymmetric Noise Suppression: Cat qubits store quantum states in superpositions of coherent photon states within superconducting microwave cavities. Two-photon dissipation exponentially suppresses bit-flips ($\vert{}0\rangle \leftrightarrow \vert{}1\rangle$), leaving only phase-flip errors to be corrected by a 1D repetition code.
Synergy with Quantum LDPC Codes: In published research with Inria (appearing in Nature Communications), Alice & Bob demonstrated how combining cat qubits with Low-Density Parity-Check (LDPC) codes can yield ultra-compact logical architectures without requiring non-local 3D wiring.
NVIDIA CUDA-Q Integration: Alice & Bob leverages GPUs and NVIDIA's CUDA-Q platform to accelerate simulation of large-scale cat-qubit systems and noise dynamics.
Elite Scientific Advisory Board: The company maintains close guidance from leading pioneers in circuit quantum electrodynamics, including 2025 Nobel Laureate Michel Devoret and Inria research director Mazyar Mirrahimi.
Future Roadmap: The Path to Useful Quantum Computing
Alice & Bob follows a clear 5-stage technical roadmap toward delivering a universal fault-tolerant machine by 2030:
Milestone | Chip Series | Architectural Objective | Status |
1. Master the Cat Qubit | Boson | Protect single physical qubits against bit-flips (>1 hour bit-flip time achieved) | Completed |
2. Build a Logical Qubit | Helium | Encode the first below-threshold logical qubit with 18 physical cat qubits | Active (2026) |
3. Fault-Tolerant Gates | Lithium | Interconnect logical qubits and demonstrate multi-qubit fault-tolerant logical gates | Planned |
4. Universal Computing | Beryllium | Implement universal gate sets via real-time magic state distillation | Planned |
5. Industrial Quantum Computer | Graphene | Deploy a 100-logical-qubit fault-tolerant quantum computer for materials science & chemistry | Target: 2030 |