Quantum Physicist, AMO & Quantum Theory

Company: Infleqtion
Location: Madison
Posted on: February 13, 2026

Job Description:

Job Description Job Description 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. 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. Analyze 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 behavior and guide experimental design. Support experimental efforts by interpreting data, diagnosing unexpected behavior, and proposing theory-driven mitigation or design changes. Self-start and execute new theoretical and modeling 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. Requirements 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 authorization to receive software or technology controlled under these U.S. export control laws and regulations without sponsorship for an export license. WORKING CONDITIONS and PHYSICAL REQUIREMENTS Work will normally be performed in an office and laboratory environment and around technical equipment including computers and lasers. We ask that candidates be able to efficiently use automated office equipment such as laptops, copiers, and printers; able to effectively engage in communications (via phone, computer, or in-person). Any required Personal Protective Equipment will be provided and must be properly used in accordance with company requirements. TRAVEL Up to 10% travel may be required. Benefits The targeted salary range for this role is $115,000 to $165,000 on an annualized basis plus eligibility to participate in our annual incentive plan. In addition to your base compensation, we offer a generous Total Rewards program which includes: 100% company paid Employee coverage for Medical, Dental, Vision, and Short/Long Term Disability insurance programs Employer funded Health Savings Account Unlimited Paid Time Off 401(k) Matching Programs Company paid Life and AD&D Insurance Flexible Healthcare Savings Account Paid FMLA Leave Paid Maternity/Paternity Leave Employer Assistance Program Student Loan Repayment Equity Program Equal Opportunity Here you have freedom to embrace your whole self: who you love, your gender identity and expression, skin color, 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. Contact Information If this opportunity interests you and you fit the job description, please submit an application. If you need assistance or an accommodation due to disability, please feel free to contact us at hr@coldquanta.com.

Keywords: Infleqtion, Arlington Heights , Quantum Physicist, AMO & Quantum Theory, Science, Research & Development , Madison, Illinois