New Perspectives for Warm Dense Matter Theory: from Quantum Monte Carlo to Temperature Diagnostics

Warm dense matter (WDM) an extreme state that is characterized by extreme densities and temperatures has emerged as
one of the most active frontiers in plasma physics and material science. In nature, WDM occurs in astrophysical objects
such as giant planet interiors and brown dwarfs. In addition, WDM is highly important for cutting-edge technological
applications such as inertial confinement fusion and the discovery of novel materials.
In the laboratory, WDM is studied experimentally in large facilities around the globe, and new techniques have facilitated
unprecedented insights into exciting phenomena like the formation of nanodiamonds at planetary interior conditions [1].
Yet, the interpretation of these experiments requires a reliable diagnostics based on accurate theoretical modeling, which is
a notoriously difficult task [2].
In this talk, I give an overview of recent developments in this field [3,4,5], which will allow for a rigorous treatment of the
intricate interplay of Coulomb coupling with thermal excitations and quantum degeneracy effects based on approximation-
free quantum Monte Carlo (QMC) simulations. Finally, I will present a new idea to extract the exact temperature [6] and
other material properties [7] from an X-ray Thomson scattering experiment without any models or simulations.
[1] D. Kraus et al., Nature Astronomy 1, 606-611 (2017)
[2] M. Bonitz et al., Physics of Plasmas 27, 042710 (2020)
[3] T. Dornheim et al., Physics Reports 744, 1-86 (2018)
[4] T. Dornheim et al., Physical Review Letters 121, 255001 (2018)
[5] M. Böhme et al., Physical Review Letters 129, 066402 (2022)
[6] T. Dornheim et al., arXiv:2206.12805
[7] T. Dornheim et al., arXiv:2209.02254