### Background and interest:

Physics and high-energy physics are considered areas where quantum devices could make a difference in simulating complex dynamic interaction or multi-body systems.

Many classes of problems used in chemistry, condensed-matter physics or high-energy physics can be simulated through well-controlled quantum systems. In high-energy physics, quite a few possible applications have been investigated in recent years, especially in the context of gauge theories and their applications to dynamic problems (e.g. heavy-ion collisions), topological problems (e.g. CP violation), or high-baryon density configurations (e.g. modelling of neutron stars).

One possible approach is to design simulation strategies that apply different techniques, a mix of classic and quantum methods, to different parts of the problems and focus the attention on those areas that are computationally intractable using standard techniques.

Many aspects of quantum devices can be understood rigorously using tools already well established in theoretical particle physics. By bringing together theoretical and experimental expertise, CERN can act as a catalyst for breakthroughs in quantum technologies and capitalise on expertise in the CERN Theory Department (CERN-TH).

One natural area of focus is to identify outstanding questions in theoretical physics that can be impacted by quantum technologies. CERN-TH has significant experience in a wide range of computationally intensive areas, including evaluating amplitudes and phase-space integrals in perturbative QCD, calculating non-perturbative dynamics using lattice quantum field theory and computational advances associated with the S-matrix bootstrap programme. Members of CERN-TH are thus in a good position to judge the potential impact of future quantum computations and benchmark the prospects against the current classical computing state of the art.

For example, expertise in CERN-TH may aid in mapping quantum field theories onto quantum devices, understanding and mitigating the effects of Hilbert-space truncations, and identifying the key advantages of real-time quantum field theory calculations. This fits into a long-term aim of understanding where a quantum advantage can be expected in high-energy physics applications and exploiting such advantages to obtain efficiency gains in computing, data processing and storage.

__The long-term goals in the field of Quantum Theory, Simulation and Information Processing are to__:

- Identify possible applications of quantum simulation and quantum information processing relevant to high-energy physics, leveraging CERN’s range of expertise, from formal perspectives to practical implementations in hardware and software.
- Support local projects focusing on quantum simulation and information processing. Identify quantum advantages and invest in their future exploitation.
- Establish global collaborations with other institutes and companies to develop quantum capabilities in combination with the unique expertise gathered at CERN.
- Benchmark the current and potential performance of quantum simulations against state-of-the-art classical computations.