Quantum effects in plasmas

The year 2025 has been designated by UNESCO as the International Year of Quantum Science and Technology. One hundred and twenty-five years ago, Max Planck's discovery of radiation quanta started the quantum era, and 100 years ago, quantum mechanics was developed by Schrödinger, Heisenberg, Bohr, Pauli, Dirac, Born, Fermi, and many others. By now, quantum mechanics is the theoretical foundation of most fields of physics and chemistry, and it is the basis for modern nanotechnology. How about plasma physics? How important are quantum effects in plasmas? In what experiments are quantum effects observed, and where do they govern the behavior of plasmas? How can these effects be treated theoretically and via computer simulations? Starting with a brief historical overview, we discuss the broad parameter range that is the characteristic of plasmas and outline where quantum effects are relevant. This is the case primarily for warm dense matter and inertial fusion plasmas. We provide an overview of the theoretical quantum methods that are available for these dense plasmas and how their respective advantages can be combined in order to achieve predictive capability. The key is a downfolding approach that is based on first-principles simulations.