Electronic pair alignment and roton feature in the warm dense electron gas

The study of matter under extreme densities and temperatures as they occur, for example, in astrophysical objects and nuclear fusion applications has emerged as one of the most active frontiers in physics, material science, and related disciplines. In this context, a key quantity is given by the dynamic structure factor S(q, ω), which is probed in scattering experiments—the most widely used method of diagnostics at these extreme conditions. In addition to its importance for the study of warm dense matter, the modelling of such dynamic properties of correlated quantum many-body systems constitutes an important theoretical challenge. Here, we report a roton feature in the dynamic structure factor S(q, ω) of the warm dense electron gas, and introduce a microscopic explanation in terms of an electronic pair alignment model. Our results will have direct impact on the interpretation of scattering experiments and may provide insights into the dynamics of a number of correlated quantum many-body systems such as ultracold helium, dipolar supersolids, and bilayer heterostructures.