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Cat-qubit roadmapAlice & Bob—Cat-qubit roadmapAlice & Bob—Cat-qubit roadmapAlice & Bob—
Cat-qubit roadmap
Photo: Nilhope · CC BY-SA 4.0 (opens commons.wikimedia.org)

Cat-qubit roadmap

by Alice & BobFR

ResearchStage 1 of 5

Building first logical qubits from cat qubits, on the way to Graphene in 2030.

Updated 17 Jun 2026Checked 25 Sep0 updates this week

Milestones

Next · Graphene: 100 logical qubits
  1. Roadmap to 100 logical qubits by 2030 publishedJan 2025Complete.
  2. First cat-qubit logical qubitsJun 2026Complete.
  3. Graphene: 100 logical qubitsTarget 2030Not yet reached.

Most important updates

  • 17 Jun 2026
  • 10 Jun 2026
  • 22 May 2026
  • Jan 2025

Upcoming

  1. 2030Graphene: 100 logical qubits (next)

Current obstacles

  • Phase-flip ratesBigger cats block more bit flips but cause more phase flips. Keeping phase errors low enough is the core challenge.

Physics limits

  • Bigger cats trade bit flips for phase flipsMore photons in the cat suppress bit flips exponentially, but phase flips rise in proportion to photon number, because each photon can leak out. The balance limits how large a cat is useful.
  • The stabilising pump adds noiseRemoving photons in pairs requires a strong pumped nonlinear circuit. The pump heats and disturbs the system, and the achievable pair-removal rate limits how fast the qubit corrects itself.
  • Still needs millikelvin coolingLike other superconducting devices, cat qubits work only near 10 mK in a dilution fridge, with microwatts of cooling for all wiring.

How it works

3 parts
A cryostat in Alice & Bob's Paris lab: the cat-qubit chips sit at its cold bottom, fed by the coaxial lines running down the stages
A cryostat in Alice & Bob's Paris lab: the cat-qubit chips sit at its cold bottom, fed by the coaxial lines running down the stagesPhoto: Nilhope · CC BY-SA 4.0 (opens commons.wikimedia.org)
Cat

Two opposite states of light

A superconducting resonator holds a light field in one of two opposite phases, like a pendulum swinging left or right; these encode 0 and 1.

Protection

Removing photons in pairs

A buffer circuit removes photons two at a time, constantly pulling the state back, so bit flips become exponentially rarer as the cat grows.

Code

A simple repetition code

With bit flips suppressed, only phase flips remain; a line of cats checking each other fixes them, needing far fewer qubits than a surface code.

Update log

4 updates

Wed 17 Jun

  • Major: PressCommercial

Wed 10 Jun

  • Major: PressHardware

Fri 22 May

  • Minor: PressFunding

Jan 2025

  • Minor: PressFunding

About Alice & Bob

The team behind Cat-qubit roadmap

Alice & Bob

Cat qubits, superconducting, bit-flip protection

Paris startup (2020) building superconducting cat qubits. They hold information in two states of a microwave resonator, which strongly suppresses bit-flip errors. Only phase flips need fixing, which could cut the qubits error correction needs.

  • Raised €100M Series B in January 2025.
  • Roadmap targets Graphene, a 100-logical-qubit machine, by 2030.
  • Cat qubits need only a simple repetition code, not a full surface code.

alice-bob.com (opens alice-bob.com)Company profile →

Founded
20206 yrs
Headquarters
France
Status
Private
Valuation
private
Raised
$104M1 round
Last round
Series B · $104MJan 2025
Works in
QuantumSuperconducting
Coverage
1 program · 4 updateslatest 17 Jun 2026checked 25 Sep
Lead investors
Future French ChampionsAVPBpifrance
People
Théau PeronninCo-founder and CEORaphaël LescanneCo-founder and CTO
Primer