Physics of Light Dense Matter: Quantum and Classical Effects*

Restricting the volume of a material, through application of pressure, changes the dominance of interactions within the material, and exposes unnatural states of matter not found in our predominantly adiabatic universe. One of the most exotic phenomena in condensed matter is the phase transitions purely driven by quantum effects. While quantum fluctuations in electronic states are always relevant, it is also possible to observe quantum effects in lattice of very light elements. At ambient conditions, the lightest metal of the periodic system is lithium. Similar to hydrogen and helium even at zero temperature lattice of lithium remains far from static and a fascinating system to explore the lattice quantum effects in light dense matter.
In this talk I will review some of the major goals of research in high pressure physics in exploring the quantum effects in ultra-light dense matter and discuss how nuclear quantum effects affect the structural stability and superconductivity of compounds of ultra-light materials including superhydrides. I will present some of our studies on exploring the signature of lattice quantum contributions to the structural phase transitions of lithium at low temperature, the effect of pressure on the evolution of Fermi surface of lithium and present our results on resolving the long-lasting mystery of lithium ground state.