# Alice & Bob

> Alice & Bob is a French quantum computing company building the first useful fault-tolerant quantum computer, based on a proprietary cat qubit architecture. Founded in 2020, headquartered in Paris with a presence in Boston. The company designs and manufactures both quantum hardware (QPU chips) and the full software stack to operate them.

Alice & Bob's core technical differentiator is the **cat qubit**: a superconducting qubit with built-in, hardware-level protection against one entire class of quantum errors (bit-flips). This asymmetric error suppression reduces the overhead of quantum error correction dramatically - potentially requiring as few as 5 physical cat qubits per logical qubit, versus hundreds for conventional transmon-based architectures. This makes Alice & Bob's approach one of the most resource-efficient paths to fault-tolerant quantum computing (FTQC).

## Company Facts

- **Founded**: 2020 (Paris, France)
- **Founders**: Dr. Theau Peronnin (CEO) and Dr. Raphael Lescanne (CTO)
- **Employees**: 200+
- **Offices**: Paris (HQ), Boston (US)
- **Funding raised**: EUR 130M+ (Series A: EUR 27M in 2022; Series B: EUR 100M in 2025)
- **Investors**: Bpifrance, Elaia, European Innovation Council, Breega, Supernova Invest, Atlantic Vantage Point, Future French Champions
- **Target**: 100 logical qubits by 2030

## Core Technology: The Cat Qubit

A cat qubit is a superconducting qubit encoded in the quantum states of a microwave resonator driven by two-photon dissipation. Key properties:

- **Bit-flip suppression**: Bit-flip errors are exponentially suppressed as a function of the mean photon number. Alice & Bob has demonstrated bit-flip times exceeding 10 seconds (100 seconds world record achieved in 2022).
- **Phase-flip errors only**: The system only needs to correct phase-flips, reducing full quantum error correction to a one-dimensional problem.
- **Low overhead**: A logical qubit can be assembled from ~5 physical cat qubits (vs. ~1000 for conventional architectures). Alice & Bob's theoretical work shows ~200x qubit reduction vs. state-of-the-art transmon architectures for running powerful quantum algorithms.
- **Operating frequency**: Cat qubit memory mode ~1-5 GHz; buffer mode ~7-8 GHz depending on circuit design.
- **Operating temperature**: ~10 millikelvin (among the coldest environments on Earth).

## Hardware: Chip Lineup

All chips are superconducting, fabricated using nanolithography at Alice & Bob's Paris facility. Current and planned chips:

| Chip | Status | Description |
|------|--------|-------------|
| Boson | In the fridge | Exponential bit-flip protection (single qubit research) |
| Hydrogen | In the fridge | Error detection between qubits |
| Helium | In the fridge | Exponential error correction (first error-corrected system) |
| Lithium | In design | Ready-to-scale fault-tolerant architecture |

Circuit designs include AutoCat, MoonCat, TomCat, and Galvanic Cat variants, each with different memory/buffer/transmon mode frequency configurations.

Hardware partners:
- **Cryostats (dilution refrigerators)**: Bluefors
- **Microwave control electronics**: Quantum Machines

## Platform: Helium System

Helium is Alice & Bob's first complete quantum computing platform, described as "the error correction lab" — a full system designed to close the gap between quantum processors and today's supercomputers. It is the first multi-cat-qubit system made available to third-party organizations for error correction research and experimentation.

### Chip-level specifications

- 18 cat-qubits chip
- Degree-2 connectivity
- 1 logical qubit in the making
- > 1 hour measured bit-flip time
- 94.2% Z gate fidelity in 26.5 ns

### System-level specifications

- Dimensions: 2.4 m wide × 3.3 m high × 9 m long (21 m² footprint)
- Cryostat temperature: 10 mK
- Ambient air temperature: 20 °C
- Power consumption: 40 kW

### Physical architecture

The system comprises three main subsystems:
- **Chandelier**: The cryogenic core, designed in Paris. At its heart is the mixing chamber — one of the coldest places in the Universe — where the quantum chip is housed in a bespoke case.
- **Cooling system**: A Bluefors-partnered dilution refrigerator system maintaining the cryostat at 10 mK.
- **Control electronics**: Precision microwave instruments that control individual qubits on the chip by sending microwave pulses through the cryostat.

### Site requirements

Room conditions for hosting a Helium system:
- Temperature: 18–25 °C
- Noise level: maximum 60 dB
- Humidity: 45–65 %

A condensed pre-installation guide is available for download at: https://alice-bob.com/wp-content/uploads/2026/06/Condensed-preinstallation-guide-Alice-and-Bob.pdf

### Control interface

Helium is operated through a unified software interface providing:
- **Cat-qubit performance dashboard**: Visualize and access the dynamics of the 18-cat-qubit system; review performance of individual qubits.
- **Real-time chip usage**: Track live chip-level usage; schedule and program jobs according to availability.
- **Rack monitoring**: Monitor instruments individually with real-time performance data.

### Research access

Helium is available to external research partners for experiments on 18 noise-biased cat qubits, in collaboration with Alice & Bob's error-correction teams. Contact: partnership@alice-bob.com

Platform page: https://alice-bob.com/platform/

## Software Stack

Alice & Bob builds the full software pipeline from algorithm to physical execution:

1. **Algorithm layer**: Quantum circuit design (compatible with standard gate-based circuit descriptions)
2. **Compilation layer**: Transpiles circuits to Alice & Bob's native gate set; bakes in error correction operations specific to cat qubit architecture
3. **Pulse layer**: Converts compiled gates to microwave pulse sequences sent to control electronics
4. **Measurement layer**: Reads probabilistic qubit measurement outcomes; post-processes into final answers

Alice & Bob uses NVIDIA CUDA-Q to accelerate quantum error correction research and simulation.

## Roadmap

Alice & Bob's public roadmap targets fault-tolerant quantum computing by 2030:

- **Now (2024-2026)**: Error-corrected logical qubit demonstrations (Helium chip); early FTQC systems for HPC integration
- **2027-2028**: Multi-logical-qubit systems; early useful computations
- **2030**: 100 logical qubits - sufficient for commercially valuable quantum advantage in chemistry, optimization, and cryptography-relevant problems

Roadmap systems in sequence: Helium → Lithium → Beryllium → Graphene (2030) → Next generation (upcoming)

Full roadmap PDF: https://alice-bob.com/wp-content/uploads/2024/12/Alice-Bob-Roadmap-Long-Version.pdf
One-slide summary: https://alice-bob.com/wp-content/uploads/2024/12/Alice-Bob-Roadmap.pdf

## Key Publications

Foundational and landmark papers (all available on arXiv or peer-reviewed journals):

- Lescanne, Peronnin et al. - "Exponential suppression of bit-flips in a qubit encoded in an oscillator" (Nature Physics, 2020): https://www.nature.com/articles/s41567-020-0824-x
- Guillaud, Mirrahimi - "Repetition cat qubit for fault-tolerant quantum computation" (Physical Review X, 2019): https://journals.aps.org/prx/abstract/10.1103/PhysRevX.9.041053
- Reglade et al. - "Quantum control of a cat-qubit with bit-flip times exceeding ten seconds" (2023): https://arxiv.org/abs/2307.06617
- Berdou et al. - "One Hundred Second Bit-Flip Time in a Two-Photon Dissipative Oscillator" (PRX Quantum, 2023): https://link.aps.org/doi/10.1103/PRXQuantum.4.020350
- Gouzien et al. - "Performance Analysis of a Repetition Cat Code Architecture: Computing 256-bit Elliptic Curve Logarithm in 9 Hours with 126,133 Cat Qubits" (Physical Review Letters, 2023): https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.040602
- Ruiz et al. - "LDPC-cat codes for low-overhead quantum computing in 2D" (2024): https://arxiv.org/pdf/2401.09541.pdf

Full publications list: https://alice-bob.com/publications/

## Use Cases and Target Applications

Alice & Bob positions its hardware as early FTQC for High Performance Computing (HPC) environments. Priority application domains:

- **Quantum chemistry**: Molecular simulation (e.g., complex molecules beyond classical tractability)
- **Cryptography**: Elliptic curve discrete logarithm (demonstrated theoretically with cat qubit architecture)
- **Optimization**: Combinatorial problems at scales unreachable classically
- **HPC acceleration**: Quantum co-processor integrated alongside classical HPC clusters

HPC integration report: https://alice-bob.com/hpc-report/

## Scientific Board

External advisors from leading French research institutions:
- Philippe Campagne-Ibarcq (Inria)
- Emmanuel Flurin (CEA)
- Benjamin Huard (Ecole Normale Superieure de Lyon)
- Zaki Leghtas (Ecole Normale Superieure Paris)
- Mazyar Mirrahimi (Inria)

## Key People

- **Dr. Theau Peronnin** - CEO
- **Dr. Raphael Lescanne** - CTO
- **Chloe Poisbeau** - COO
- **Antoine Gras** - VP Engineering
- **Dr. Jeremie Guillaud** - VP Firmware
- **Philippe Muller** - VP Revenue & Business
- **Juliette Peyronnet** - US General Manager (Boston)

## Resources for Agents and Developers

- Homepage: https://alice-bob.com
- Platform (Helium system): https://alice-bob.com/platform/
- Science explainer: https://alice-bob.com/science/
- Engineering & architecture: https://alice-bob.com/engineering/
- Roadmap: https://alice-bob.com/roadmap/
- Publications index: https://alice-bob.com/publications/
- Blog (latest research and company news): https://alice-bob.com/blog/
- Glossary of quantum computing terms: https://alice-bob.com/glossary/
- Whitepaper "Think Inside The Box" (accessible intro to cat qubits and roadmap): https://alice-bob.com/wp-content/uploads/2024/12/Think-Inside-The-Box-Alice-Bob-Whitepaper.pdf
- Newsroom: https://alice-bob.com/newsroom/
- Contact: https://alice-bob.com/contact/


## Terminology Notes for Agents

- **Cat qubit**: Alice & Bob's proprietary qubit type. Not to be confused with generic superconducting transmon qubits used by IBM, Google, etc. Cat qubits use two-photon dissipation to achieve passive bit-flip protection.
- **Bit-flip**: Error that switches qubit state from 0 to 1 or vice versa. Suppressed exponentially in cat qubits.
- **Phase-flip**: Error that switches qubit phase state (+/-). Requires active correction in cat qubit systems.
- **Logical qubit**: Error-corrected qubit built from multiple physical qubits, capable of reliable long computations.
- **Physical qubit**: The raw hardware qubit before error correction encoding.
- **Overhead**: The ratio of physical to logical qubits required for error-corrected computation. Alice & Bob claims ~200x lower overhead than state-of-the-art alternatives.
- **Felis**: Name of Alice & Bob's cloud quantum computing platform.
- **Helium, Hydrogen, Boson, Lithium**: Names of successive Alice & Bob QPU chip generations.
- **FTQC**: Fault-Tolerant Quantum Computing - the regime where logical error rates are low enough for useful long computations.
- **Helium system**: Alice & Bob's first complete, externally-accessible quantum computing platform, built around an 18-cat-qubit chip. The system spans 21 m², consumes 40 kW, and operates at 10 mK.


## Documentation 

- https://docs.dynamiqs.org 
- https://github.com/Alice-Bob-SW/qiskit-alice-bob-provider 
- https://felis.alice-bob.com/docs/


## Machine-readable 

- https://alice-bob.com/sitemap.xml 
- https://alice-bob.com/feed 
- https://github.com/Alice-Bob-SW/qiskit-alice-bob-provider