Speaker
Description
Arrays of individually controlled atoms and ions have emerged as a leading experimental platform for both the exploration of complex quantum matter and the development of quantum technologies. However, guiding these efforts with reliable theoretical predictions is hard: the numerical cost of exact calculations grows exponentially with system size and quickly overwhelms even the largest computers. This challenge can be addressed by combining a semiclassical method, the truncated Wigner approximation, which takes leading-order quantum corrections into account, with large-scale parallel computation on CPU and GPU clusters. The approach replaces the full quantum evolution by a large ensemble of individual trajectories that can be calculated independently by solving coupled differential equations, making the problem naturally suited to high-performance computing.
The computational challenge arises from the combination of several requirements. The long-range interactions between the atoms couple every lattice site to every other, and the physics of interest unfolds over timescales orders of magnitude longer than the microscopic one, demanding many small timesteps per trajectory. Reliable estimates of observables in turn require averaging over large ensembles of trajectories run in parallel, placing significant pressure on memory. Carrying out these simulations on bwHPC resources allows us to access system sizes and timescales well beyond the reach of exact methods.
Using this setup, we study the dynamics of dissipative Rydberg atom arrays in one and two dimensions, where the interplay between dissipation and coherent evolution gives rise to rich nonequilibrium behaviour. We find that the strong interactions between atoms can dramatically slow down the approach to equilibrium, with relaxation proceeding through long-lived intermediate states and pronounced spatial anticorrelations that persist well after the initial configuration has been lost. These findings are directly relevant for current experimental efforts to realise and control strongly interacting quantum systems in the laboratory. The full results are presented in arXiv:2604.10538.