Abstract: "Quantum materials" are heating up, and let's not forget the cuprate high-temperature superconductors being one of them. These oxides are structurally layered, host a plethora of symmetry breaking phases, and have strong electron-electron Coulomb interactions. The ultimate questions are - what makes its transition temperature (Tc) so high, and (how) can we make it higher? Angle-resolved photoemission spectroscopy (ARPES) is a powerful tool to acquire electron energy-momentum information in solid state materials. In this talk, I will first present single-particle evidence that the system Tc is strongly limited by superconducting phase fluctuations rather than only the pairing strength. Such fluctuation is shown to have deep connections to the system's low dimension and a flat band region caused by electronic correlation. Then I will demonstrate how a particular lattice vibrational mode can be activated via broken local symmetry and reduced doping, subsequently helping double the superconducting Tc. At last, I will discuss the possibility to reach a quantitative understanding of the high-Tc mechanism via a joint effort between photoemission and inelastic neutron scattering.