Novel States of Matter in Quantum Materials Under High Pressure

ABSTRACT High pressure, as a fundamental thermodynamic parameter, can be used as a clean and efficient tool to regulate interatomic distances in quantum materials, enabling precise control of lattice structure, electron correlation, spin–orbit coupling, and band topology without introducing additional chemical impurities. In this review, we summarize that high‐pressure changes in lattice symmetry, orbital hybridization, band structure, magnetic order, and electron–phonon coupling induce the emergence of new quantum states. We also distinguish that high pressure not only compresses lattice structures, but also enhances quantum effects that lead to exotic states, including unconventional superconductivity with elevated transition temperatures, disproportionate charge‐density waves, electron‐correlated driven Mott insulators, topologically protected phases versus stable topologically protected states, and fractional excited quantum spin liquids. In addition, we reconcile the contradictory experimental results in the current research field, such as the nonmonotonic variation of superconducting transition temperature with pressure in kagome metals and the controversial topological phase transition conditions in TaAs. Finally, we outline the potential applications of high‐pressure technologies, including high‐temperature superconductors, quantum computing, and emerging materials.