Founded in 2020 and based in the heart of Paris, C12’s mission is to be at the center of one of the biggest technological breakthroughs of the century and change the course of history by building a universal quantum computer.
At C12, we believe that achieving a true breakthrough in quantum computing requires rethinking the fundamentals. That’s why our founders—deeply rooted in academic and engineering excellence—have chosen carbon nanotubes as the building blocks of our quantum processors. This ultra-pure material dramatically reduces error rates, boosts performance, and minimizes hardware overhead—key ingredients for scalable, fault-tolerant quantum computing. By crafting a unique approach that scales, we aim to revolutionize quantum computing just as silicon transformed classical computing.
Since our founding, we’ve raised over €25 million in funding, published 11 scientific papers, and secured 8 patents. Today, our fast-growing team of 80+, including 25 PhDs, has over 26 nationalities represented. We have our own cutting-edge lab spaces in Paris' historic Panthéon district, where scientists, engineers, and innovators work side-by-side to tackle some of the most exciting technical challenges of our time.
If you're passionate about shaping the future of quantum technology and want to make a real impact, C12 offers a unique environment to grow, learn, and innovate.
Overview:
C12 Quantum Electronics is developing a hybrid quantum architecture based on spin qubits in carbon nanotubes, coupled through a circuit quantum electrodynamics (cQED) platform. Our approach combines the exceptional coherence properties of carbon-based qubits with high-connectivity microwave architectures, with the goal of building a fault-tolerant quantum processing unit.
The Qubit Control team sits at the heart of this effort. We develop the methods that make qubits work: tuning protocols, readout strategies, gate implementations. We optimise the control and readout electronics and protocols, explore large parameter spaces, investigate the physics of the spin qubit, and translate physical insight into engineering solutions.
Working at the intersection of quantum physics, engineering, and software, you will collaborate daily with theory and the other engineering teams — all co-located in our Paris lab to make those interactions as direct and continuous as possible.
C12 is transitioning from a phase of scientific discovery and proof-of-concept demonstrations to one of systematic scaling. This means our focus is shifting towards automation, reproducibility, and process maturity — without sacrificing the scientific rigor and curiosity that got us here.
It is a demanding and exciting moment: we are still making new science, while simultaneously building the infrastructure that will carry us to a quantum advantage demonstration. The person joining this team will need to be both a rigorous scientist and a pragmatic builder!
Responsibilities
- Design, calibrate, and optimize DC and microwave experiments in dilution cryostats equipped with state-of-the-art high-frequency control electronics
- Develop scalable measurement and analysis workflows: well-documented, reproducible, and built to run with increasing autonomy
- Sustain a close feedback loop with engineering teams to continuously improve device performance
- Work closely with the theory team to connect experimental observations with physical models
- Actively collaborate with the software team to execute our automation roadmap — from experiment scheduling to data analysis — as we scale toward a full QPU
- Deepen our understanding of spin qubits in carbon nanotubes integrated within high-impedance cQED architectures
About you
- You are driven by the scientific and engineering challenge of building a quantum computer, and you want to contribute to a meaningful milestone in the field
- You hold a PhD (or Masters with substantial research experience) in quantum physics or a closely related discipline
- You have hands-on experience with quantum experiments — DC transport, microwave spectroscopy, or both
- You write Python fluently and use it autonomously to control experiments, process data, and build reusable tools
- You hold yourself to high scientific standards and are equally motivated by results
- You communicate clearly in English, in writing and in conversation, across technical and non-technical audiences
This is the salary range for a mid-senior profile. That said, we still encourage you to apply, even if you don't meet all the requirements.
Rest assured, we are committed to finding the right fit for our team and are open to adjusting compensation based on skills and experience.
What we offer:
- Stock options for every employee (BSPCE/ESOP)
- Two incredible office spaces in the heart of Paris (both next to the famous Panthéon!)
- Sponsored trip to conferences around the world
- Swile meal vouchers
- Vibrant office culture (team lunches, offsite events, Friday breakfasts..)
- Mental health support with moka.care
- Training budget/ Annual Learning & Development Allowance
- Sabbatical leave (after 2 years in the company)
You should join us if...
- You like hands-on work and technology
- You want to contribute to achieving landmark results in quantum computing, making a difference in the emerging quantum technologies
- You want to work within a team of 80+ people with various backgrounds in nanofabrication, quantum electronics, and carbon nanotube science to create a revolutionary quantum computing processor
- You want to thrive in an exceptional scientific environment with several industrial and academic partners
- You share our values (excellence, scientific integrity, diversity, curiosity, and care) and want to help us define our product-focused culture and ambition to accelerate
C12 encourages all who feel qualified to apply. Recruitment decisions are based solely on qualifications, skills, knowledge and experience.
Applications from women are encouraged and welcomed!
We may use artificial intelligence (AI) tools to support parts of the hiring process, such as reviewing applications, analyzing resumes, or assessing responses and identifying potential inconsistencies or verification signals in application materials based on available information. These tools assist our recruitment team but do not replace human judgment. Final hiring decisions are ultimately made by humans. If you would like more information about how your data is processed, please contact us.
TECHNICAL & MARKET ANALYSIS | Appended by Quantum.Jobs
The integration of Experimental Quantum Physicists into the commercial hardware sector signifies a critical transition from fundamental discovery to the industrialization of high-fidelity processing units. These roles are structurally necessary to bridge the gap between theoretical material science and the engineering of scalable, fault-tolerant architectures, particularly within emerging modalities like carbon-based spin qubits. By converting abstract physical insights into reproducible control protocols, this function mitigates the systemic risks associated with hardware overhead and error rates in early-stage quantum processors. Market signals from global technology strategies highlight that such expertise is the primary determinant of whether a platform can successfully navigate the transition from laboratory proof-of-concept to systematic scaling. Consequently, this role type serves as a high-leverage node within the hardware value chain, ensuring that quantum Advantage is not only scientifically possible but architecturally achievable.
The quantum hardware landscape is undergoing a decisive shift toward the maturation of diverse qubit modalities, where the primary bottleneck has moved from basic operation to the requirements of large-scale reproducibility. While superconducting and trapped-ion systems have established early benchmarks, the ecosystem is increasingly exploring alternative materials that offer inherent advantages in coherence and connectivity. This diversification necessitates a workforce capable of managing the complex interface between solid-state physics and high-frequency control electronics, particularly as organizations strive for fault tolerance. Current sector-wide focus lies on bridging classical and quantum capabilities at scale, requiring sophisticated orchestration of cryogenics, microwave engineering, and real-time data analysis.
Workforce scarcity remains acute at the intersection of experimental physics and systems engineering. As the industry moves beyond the Noisy Intermediate-Scale Quantum (NISQ) era, the structural necessity for researchers who can implement automated measurement workflows is paramount to resolving the translation gap. Industry dynamics are heavily influenced by the need for process maturity, where scientific rigor must be reconciled with the pragmatic demands of hardware-software integration. This evolution is critical for maintaining momentum as technologies move through varying Technology Readiness Levels (TRLs) toward commercial utility.
Furthermore, the stability of the quantum value chain depends on the ability of experimental teams to establish a closed feedback loop with theory and software divisions. This cross-functional coupling is essential for optimizing device performance and ensuring that emerging hardware is compatible with the developing software stack. As public and private funding cycles prioritize measurable milestones, the role of the experimental physicist transitions from an isolated researcher to a strategic builder of the infrastructure required for the first generation of universal quantum computers.
The capability architecture for this role type centers on the synchronization of low-temperature DC transport and microwave spectroscopy with state-of-the-art automation tooling. Mastery of high-impedance circuit quantum electrodynamics (cQED) and spin-qubit manipulation is essential for ensuring that hardware performance aligns with the requirements of fault-tolerant algorithms. These capabilities are fundamental to the throughput of hardware organizations, as they enable the parallelization of qubit characterization and the development of scalable tuning protocols. By establishing rigorous verification and validation frameworks at the physical layer, this function provides the leverage needed to assess the scalability of new materials before full-scale capital allocation. Furthermore, the ability to build reusable software tools for experiment control reduces iteration friction between device fabrication and operational readiness. Such expertise is critical for long-term interoperability within the emerging quantum-as-a-service (QaaS) market, where hardware reliability is a primary competitive differentiator. - Accelerates the deterministic transition from scientific discovery to the systematic scaling of quantum processing units
- Mitigates systemic execution risks by optimizing the control protocols of high-coherence carbon-based qubit architectures
- Facilitates the integration of experimental observations into predictive physical models for hardware performance enhancement
- Strengthens the reliability of technology roadmaps through the implementation of automated and reproducible measurement workflows
- Reduces iteration friction between material science breakthroughs and the deployment of scalable control electronics
- Optimizes the allocation of specialized technical talent across experimental, theoretical, and software engineering portfolios
- Enhances the stability of the hardware value chain by providing predictable performance benchmarks for external stakeholders
- Supports the scaling of quantum architectures by managing the complex dependencies of high-connectivity microwave platforms
- Improves the transparency of TRL progression for institutional investors and national technology policy observers
- Enables the structural reproducibility of quantum experiments through the standardization of analysis and calibration routines
- Protects high-capital R\&D investments by ensuring alignment between fundamental physics and industrial-grade engineering
- Orchestrates the convergence of academic research excellence with the practical demands of building universal quantum systemsIndustry Tags: Quantum Hardware, Spin Qubits, Carbon Nanotubes, cQED Platform, Fault-Tolerant Computing, Cryogenic Engineering, Microwave Spectroscopy, Experimental Physics, Deep Tech Scaling
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