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. 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. 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! 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! Your role at C12 Quantum Electronics: 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. We are seeking a skilled Instrumentalist / Metrologist to own the measurement chain.   Key responsibilities: You are responsible for the error budget of the quantum gates (measurement, monitoring, improvement). You are accountable for the cryogenic DC and microwave control and readout chains whose performance have to be understood perfectly to determine qubit limitations, replicated across multiple identical machines, eventually operating in a data center without a cryogenics expert on site. Quantum Instrumentation and metrology:  - Own the end-to-end signal budget of each cryogenic setup: noise temperature, insertion loss, crosstalk, dynamic range, photon number delivered to the device, calibration of TWPAs, magnetic field measurements. - In collaboration with the quantum physicists, quantify the impact of noise sources on qubit coherence and operation fidelities, calibrate pulses to optimize qubit readout and gate fidelities, design and test new measurement protocols. - Design the dashboard to monitor performance metrics of the qubits and setups. Monitor and systematically improve figures of merit, ensure homogeneous performance across the park.  Provide structured, quantitative feedback to R&D teams (superconducting resonator design and fabrication, carbon nanotube growth and characterization).  - Drive setup upgrades and new installations from specification through commissioning and acceptance testing, including supplier selection and technical follow-up. Measurement chain robustness and readiness for scaling :  - Co-design specifications for the integration of the measurement chain, own the qualification and validation chain against agreed system requirements. - Work closely with Engineering to derive system requirements into technical requirements for the measurement chain of the product, and to define the associated metrology, verification and validation methods.  Transfer and team support:  - Write the documentation that turn your work into shared team capability.  - Train and support quantum physicists and engineers on the setups and the measurement protocols and maintain common standards accross setups. About you: - You are driven by the engineering and scientific challenge of building a quantum computer , and you want to contribute to a meaningful milestone in the field. - You hold a PhD in experimental physics or metrology , you have at least two years of additional experience as post-doctoral researcher or in industry. - We are deliberately open on the sub-field:  Superconducting or semiconductor qubits, quantum sensing or communications, atomic or optical metrology, astronomy or particle physics instrumentation, and similar backgrounds are all welcome. - You have a proven track record of building, characterizing, and optimizing complex experiments . - You have a strong experience with RF experiments: pulse sequencing, phase noise, IQ up/down conversion) and dilution fridges (cryogenic wiring, thermalization, shielding, fault diagnosis. - You have strong analytical skills and a solid understanding of statistical methods.     - You are rigorous and well organised. - 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 you know when a result is solid enough to act on. - You communicate clearly in English, in writing and in conversation, across technical and non-technical audiences. You'll thrive if... - You love the combination of hands-on lab work and industrial challenges. - You want to be part of a team making landmark contributions to quantum computing at a moment when the field is maturing fast. - You are energized, not daunted, by a fast-paced environment with an ambitious roadmap and high expectations. - You want to work in a genuinely collaborative culture, a 90-person team spanning resonator fabrication, nanotube engineering, software, and theory, all under one roof. - You share our values: scientific excellence, integrity, curiosity, care, and a commitment to building something that matters. What we offer: 66,000 euros - 78,000 euros yearly base salary Stock options for every employee (BSPCE/ESOP) Sponsored trip to conferences around the world A highly dynamic international team Swile meal vouchers Mental health support with moka.care Training budget/ Annual Learning & Development Allowance Sabbatical leave (after 2 years in the company) Vibrant office culture (two office spaces in the heart of Paris, team lunches, offsite events, Friday breakfasts..) 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 We still encourage 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 compensations based on skills and experiences. Applications from women are especially welcomed!

Senior Quantum Instrumentalist / Metrologist

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