Computational Physicist Jobs in Colorado (NOW HIRING)

Xcimer Energy leverages decades of research on Inertial Fusion Energy (IFE) combined with groundbreaking new laser architecture. Our mission is to deploy fusion power plants to meet global decarbonization goals as fast as possible. Xcimer has assembled a team of leaders in tough tech, fusion science, and manufacturing with a track record of rapid execution. Supported by leading investors, Xcimer is uniquely positioned to deliver limitless, clean, fusion power to combat climate change. Join us in powering a better world with inertial fusion!
This is a full-time, onsite role based at our headquarters in Denver, CO.
As a Laser Plasma Interaction (LPI) Computational Physicist, you will develop and extend Xcimer's laser plasma interaction (LPI) modeling capabilities through both community simulation tools and next-generation in-house code development. You will support the development of computational frameworks that model collisional plasma kinetics, paraxial laser propagation, and coupled LPI phenomena critical to Xcimer's fusion systems. We are looking for physicists to apply their expertise in plasma physics, scientific computing, and high-performance simulation to positively impact the future of energy!
Responsibilities

• Deploy, configure, and extend existing simulation tools such as WarpX and LPSE to model laser plasma interaction phenomena relevant to Xcimer's laser architecture.
• Develop workflows, simulation setups, post-processing pipelines, and benchmarking methodologies for efficient and repeatable simulation execution.
• Lead the design and development of in-house LPI simulation software focused on collisional kinetics and paraxial laser propagation models.
• Architect simulation software using modular, extensible, and maintainable scientific software frameworks with strong emphasis on composability and long-term scalability.
• Implement and validate core physics models including collisional plasma kinetics, paraxial laser propagation, stimulated Raman scattering (SRS), stimulated Brillouin scattering (SBS), filamentation, and cross-beam energy transfer (CBET).
• Perform verification, convergence studies, and benchmarking against existing tools, published results, and experimental data to ensure numerical robustness and model credibility.
• Optimize simulation software for high-performance computing environments, including parallelization and scalability across modern compute architectures.
• Maintain rigorous software engineering practices including version control, automated testing infrastructure, documentation, and reproducibility standards.
• Collaborate cross-functionally with laser architecture, gas optics, radiation hydrodynamics, experimental physics, and other engineering teams to prioritize simulation efforts and integrate modeling outputs into broader system development activities.
• Contribute to Xcimer's long-term computational modeling strategy by identifying opportunities to integrate new physics capabilities and couple simulation domains through shared modular architectures.

Qualifications

• Education: PhD in Computational Physics, Plasma Physics, Applied Physics, or a closely related technical field.
• Strong software development skills in scientific computing using modern C++ and Python.
• Experience developing physics simulation codes with emphasis on modular software architecture, maintainability, and software quality.
• Strong understanding of laser plasma interaction physics, collisional plasma kinetics, and laser propagation models.
• Familiarity with numerical methods for partial differential equations, kinetic plasma simulations, and/or paraxial wave equations.
• Experience using, extending, or validating community simulation tools such as particle-in-cell (PIC) or fluid plasma codes.
• Experience working independently and leading technically complex software development efforts.
• Must be a U.S. citizen or national, U.S. permanent resident (current Green Card holder), or lawfully admitted into the U.S. as a refugee or granted asylum.

Desired

• Experience with WarpX, LPSE, pF3D, or similar laser plasma interaction simulation tools.
• Experience with high-performance computing, including MPI/OpenMP parallelization and/or GPU acceleration.
• Familiarity with modern scientific software architectures including plugin systems, composable frameworks, or modular physics engines.
• Experience within inertial confinement fusion (ICF), high-energy-density physics, or advanced plasma modeling environments.
• Demonstrated experience building extensible scientific software platforms that support long-term collaboration and multi-user development.

$170,000 - $210,000 a year
Candidates may be considered for other positions at Xcimer Energy, and our actual base salary will be determined on an individual basis and may vary based on job-related knowledge and skills, education, and experience. The range is published in accordance with Colorado Equal Pay for Equal Work Act and California Equal Pay Act.
Equal Employment Opportunity
Xcimer Energy is proud to be an Equal Opportunity/Affirmative Action Employer and is committed to attracting, retaining, and developing a highly qualified, diverse, and dedicated work force. Xcimer Energy hires and promotes people on the basis of their qualifications, performance, and abilities. We support the establishment and maintenance of a workplace that fosters trust, equality, and teamwork, in which all employees recognize and appreciate the diversity of individual team members. We provide all qualified applicants for employment and employees with equal opportunities for hire, promotion, and other terms and conditions of employment, regardless of their race, color, religion, gender, sexual orientation, gender identity, national origin/ethnicity, age, physical or mental disability, genetic factors, military/veteran status, or any other status or characteristic protected by federal, state, and/or local law. Xcimer Energy will consider for employment qualified applicants with criminal histories in a manner consistent with applicable federal, state, and local laws. For more information on "EEO Is the Law," please see here and here.
Benefits
Xcimer offers a comprehensive benefits package designed to support employee health, well-being, and long-term success. Benefits include medical, dental, and vision coverage; basic and supplemental life insurance; short- and long-term disability; paid parental leave for employees at the time of birth or adoption; and a 401(k) with a company match of up to 6%. Eligible employees also receive equity, allowing them to share in the company's long-term success.
Xcimer operates under a flexible Paid Time Off (ATO) approach. Rather than a fixed number of vacation days, employees are trusted to take the time they need to rest and recharge while meeting the expectations of their role and team. In addition, employees receive paid sick time, 13 company-paid holidays, and an annual paid company shutdown. Benefits are available to regular employees, including part-time and fixed-term roles, as well as interns, with eligibility varying by benefit.
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.