Quantum Many-Body Dynamics and Noisy Intermediate-Scale Quantum Computers: Interconnections, Near-Term Applications, and Novel Simulation Schemes

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Simulating the dynamics of quantum many-body systems is notoriously difficult as the computational requirements grow dramatically with increasing system size. While fully-fledged quantum computing may provide a means to handle this challenge, today's noisy intermediate-scale quantum (NISQ) devices are prone to errors and decoherence. This interdisciplinary project promises significant progress in the understanding of nonequilibrium quantum systems and in leveraging the capabilities of NISQ devices for this purpose. The innovative research is going to capitalize on the concept of quantum typicality to explore near-term applications of random quantum states on NISQ devices and to study the emergence of hydrodynamics in isolated quantum systems. By combining state-of-the-art theoretical and numerical approaches with simulations on available quantum hardware, important insights will furthermore be gained into the universal properties of quantum dynamics in driven-dissipative systems, in monitored circuits consisting of unitary gates and projective measurements, and in many-body localized systems coupled to a thermal bath. Tackling these key areas will provide a deeper understanding of fundamental physics and will unravel the inevitable interaction of NISQ devices with their environment. Results may open up new avenues for robust and scalable simulations on NISQ devices, which is vital as quantum technology continues to mature. Additionally, this project will deliver novel NISQ-inspired classical simulation schemes, which are memory-efficient and will pave the way to answer open questions that are challenging for other methods. Highlighting the strong synergy and profound interplay between quantum many-body dynamics and NISQ devices, this project follows Horizon Europe's strategic plan of developing key digital and emerging technologies and is in line with Europe's Quantum Flagship initiative to foster European excellence in quantum technologies.