Efficient Cat Qubit Simulation Intern M/F à Paris, France

Alice & Bob is developing the first universal, fault-tolerant quantum computer to solve the world’s hardest problems.

The quantum computer we envision building is based on a new kind of superconducting qubit: the Schrödinger cat qubit ‍⬛. In comparison to other superconducting platforms, cat qubits have the astonishing ability to implement quantum error correction autonomously!

We're a diverse team of 250+ brilliant minds from over 35 countries united by a single goal: to revolutionise computing with a practical fault-tolerant quantum machine. Are you ready to take on unprecedented challenges and contribute to revolutionising technology? Join us, and let's shape the future of quantum computing together!

PURPOSE OF THE ROLE

In a context where bit flips in cat qubits are exponentially rare, and where the Hilbert space grows quickly as soon as several modes are involved, estimating bit-flip probabilities in multi-mode operations lies beyond the reach of both brute-force simulation and exact master-equation methods.

The Research Intern — Efficient Cat Qubit Simulation addresses this gap by making such estimates computationally tractable, so that error rates of multi-qubit operations can be quantified and better understood.

Reporting to the Device Theorist, you will work closely with the Simulation Model team to explore how tensor-network representations, quantum trajectories and efficient simulation techniques can be combined to estimate bit-flip probabilities in many-mode settings, building on efficient simulation methods already developed for a single cat qubit.

Responsibilities:

1. Develop simulation methods for many-mode cat-qubit systems

• Combine tensor-network representations with quantum trajectory unravelings of the Lindblad master equation to simulate multi-mode operations 
• Verify the numerical robustness of the simulations (Hilbert-space and bond-dimension truncation, solver stability and precision)

2. Develop efficient simulation strategies for many-mode bit flips

• Extend efficient simulation methods developed for a single cat qubit to multi-mode systems
• Extract statistically reliable estimates of bit-flip probabilities and rates from the simulated trajectories

3. Validate and benchmark the approach

• Compare estimates against exact references where they exist (master-equation results, single-qubit simulation results) and against theoretical predictions 
• Quantify the computational cost and scaling of the method relative to standard Monte Carlo sampling

4. Interpret the physics of bit flips in multi-mode operations

• Analyse simulated bit-flip trajectories to characterise the underlying error mechanisms 
• Identify and explain discrepancies between simulated behaviour and theoretical expectations

5. Document and communicate results

• Document methods, code and results for reuse by the Simulation Model team
• Present progress in regular team meetings and formulate recommendations for extending these simulation methods to further multi-qubit operations

Requirements:

You are a Master's or final-year engineering student with a strong background in quantum physics and numerical methods. You are motivated by research at the interface of theory and computation, and are able to drive a technical project with a high degree of independence while seeking feedback from more experienced colleagues.

• LANGUAGES: Proficient in English
• Good understanding of quantum mechanics and open quantum systems (density matrices, Lindblad master equations)
• Programming experience in Python or Julia for scientific computing
• Autonomy and comfort with open-ended research questions that have no guaranteed answer
• Clear technical communication and a collaborative attitude within a multidisciplinary team
• EXPERIENCE: No prior professional experience required

Nice to have:

• Familiarity with quantum trajectories and stochastic unraveling
• Exposure to tensor-network methods (e.g. matrix product states)
• Knowledge of Monte Carlo methods and statistical estimation
• Experience with Julia, numerical ODE/SDE solvers, or GPU-accelerated and high-performance computing
• Habit of rigorous numerical practice (convergence checks, truncation control, precision and solver choice)
• Experience reading and applying current research literature
• A previous research, project or internship in quantum physics or scientific computing is an asset

Benefits:

- 1 day off per month

- Half of transportation cost coverage (as per French law)

- Meal vouchers with Swile, as well as access to a fully equipped and regularly stocked kitchen

Research shows that women might feel hesitant to apply for this job if they don't match 100% of the job requirements listed. This list is a guide, and we'd love to receive your application even if you think you're only a partial match. We are looking to build teams that innovate, not just tick boxes on a job spec.

You will join of one of the most innovative startups in France at an early stage, to be part of a passionate and friendly team on its mission to build the first universal quantum computer!

We love to share and learn from one another, so you will be certain to innovate, develop new ideas, and have the space to grow.