Senior Experimental Quantum Physicist

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.

You role at C12 Quantum Electronics: 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.

A company at an inflection point: 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.

Key responsibilities:

• You will design, calibrate, and optimize DC and microwave experiments in dilution cryostats equipped with state-of-the-art high-frequency control electronics

• You will develop scalable measurement and analysis workflows: well-documented, reproducible, and built to run with increasing autonomy

• You will sustain a close feedback loop with engineering teams to continuously improve device performance

• You will work closely with the theory team to connect experimental observations with physical models

• You will actively collaborate with the software team to execute our automation roadmap — from experiment scheduling to data analysis — as we scale toward a full QPU

• You will 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 additional experience as post-doctoral researcher or in the industry

• You have hands-on experience with quantum experiments — Qubits, DC transport, microwave spectroscopy,...

• Hands-on experience in instrumentation, metrology, or automation of complex experiments is a key strength

• 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

• You have experience in mentoring and supervising PhD students or interns

• You have experience working in a company in a similar domain

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!