Infleqtion is on a mission to commercialize atom-based quantum technologies that deliver orders-of-magnitude improvements in sensing and computing applications. As a deep-tech startup, we embrace a results-driven, fast-paced, and customer-focused approach to innovation. We are seeking self-motivated, energetic individuals with exceptional problem-solving and technical skills to help drive our Quantum Computing mission forward. For this theory-focused role, we encourage applications from physicists with expertise in theoretical or experimental Atomic, Molecular, and Optical (AMO) physics, particularly those with experience in the coherent control of quantum systems and design and characterization of quantum gates.

Location

Infleqtion has offices in the USA, United Kingdom and Australia. This is a full-time hybrid position in our Oxford Offices.

Role and responsibilities

• Develop theoretical models of neutral-atom quantum systems to inform system architecture, gate design, and hardware requirements.
• Work closely with experimental physicists and hardware engineers to translate physical models and performance targets into actionable system and subsystem requirements.
• Analyse and quantify error mechanisms in quantum gates (e.g., decoherence, control errors, crosstalk, laser and atomic noise).
• Design, simulate, optimize, and contribute to validation of protocols for quantum gates, calibration, error-mitigation, and compilation to improve fidelity, robustness, and scalability.
• Build and maintain simulation, analysis, and optimization software used to predict system behaviour and guide experimental design.
• Support experimental efforts by interpreting data, diagnosing unexpected behaviour, and proposing theory-driven mitigation or design changes.
• Self-start and execute new theoretical and modelling efforts given well-defined goals and constraints; scope problems, prioritize approaches, and deliver results on realistic timelines.
• Mentor and teach junior team members as indirect reports. Supervise interns.

• PhD in atomic physics, quantum physics, theoretical physics, or a related field; or equivalent related professional experience (4+ years). If you have substantially more experience than this and are excited to apply, please do! We will also consider hiring at the Senior Quantum Physicist level.
• Strong background in AMO physics and quantum mechanics, including atom–light interactions.
• Demonstrated experience modeling and analyzing error mechanisms in quantum systems and quantum gates using analytical methods and numerical simulations, and translating insights into improved designs.
• Proficiency in scientific programming (Python required; experience with numerical, optimization, or simulation libraries preferred).
• Ability to collaborate closely with experimental physicists and hardware engineers, translating between theoretical models, experimental results, and system-level requirements.
• Excellent verbal and written communication skills, with the ability to clearly convey complex theoretical concepts to technical and non-technical audiences.
• Strong problem-solving skills and the ability to rapidly learn and apply new concepts.
• The ability to independently plan and execute new theoretical efforts given high-level goals and constraints.
• Ability to work effectively in a collaborative, agile team environment where engagement, feedback, and shared ownership are essential to success.

It is a plus if you have:

• Experience with neutral-atom quantum computing, Rydberg-based entangling gates, and/or optical tweezer arrays.
• Experience modeling open quantum systems, noise processes, and decoherence in realistic experimental settings.
• Experience with quantum optimal control techniques for high-fidelity quantum gates.
• Familiarity with calibration, benchmarking, and characterization protocols for quantum gates and quantum processors.
• Experience working closely with experimental teams to iterate between theory, simulation, and laboratory results.
• Familiarity with Git, Linux, and command-line tools for collaborative scientific software development.
• Enthusiasm for staying up-to-date with the latest developments in AMO physics and quantum information, and for reviewing relevant literature for the team.

Note

This position may require access to information protected under U.S. export control laws and regulations for quantum computing technology. Please note that any offer for employment may be conditioned on authorisation to receive software or technology controlled under these U.S. export control laws and regulations without sponsorship for an export license.

TRAVEL

Up to 10% travel may be required.

EQUAL OPPORTUNITY

Regardless of your interest in the quantum industry, you can take pride in the fact that Infleqtion is building an ecosystem of quantum technologies and commercial products, driving the industry towards the future. Studies reveal that while men apply for jobs when they meet an average of 60% of the requirements, women and other groups tend to apply only when they meet all the criteria. If you believe you have the potential but don't meet every single point in our job advertisement, please don't hesitate to contact us! We would love to chat with you and see how you could bring great value to our team. Our goal is to find exceptional individuals who can enrich our team culture, actively contribute, and have a genuine passion for their work. Here you have freedom to embrace your whole self: who you love, your gender identity and expression, skin colour, age, appearance, disability, neurodiversity, DNA, military/veteran status, citizenship, and other factors that make up who you are. Your uniqueness is valued, welcomed, and appreciated here. We are dedicated to providing a positive workplace and base all employment decisions on your qualifications, performance, merits, as well as business needs. We are proud to be an Equal Employment Opportunity Employer.

In addition to your base compensation, we offer a generous Total Rewards program which includes:

• Competitive salary
• Incentive Stock Option Plan
• Generous company 10% pension contribution regardless of employee contribution
• Unlimited PTO
• BUPA healthcare after probation period
• Cycle to work and Technology scheme