Applications of the gauge/gravity duality to the cuprate strange metal

We studied the mysterious behavior of a class of materials known as cuprates, of particular practical interests due to their high transition temperature to a superconducting phase, where electricity is carried without resistance. Due to the strong interactions among the electrons, these systems cannot be described in terms of any conventional theory of metals and new approaches are needed. One such approach is the holographic duality, that allows us to model strongly interacting quantum system through an higher-dimensional, but easier to treat, theory of gravity. In this thesis we used the duality to study certain features of the non-superconducting phase of cuprates, known as the strange metal. We presented how to introduce the long-range Coulomb interaction, that allowed us to model plasmon excitations experimentally observed in multilayer cuprates, and to study a phenomenon of a two-layer system known as Coulomb drag. Furthermore, we showed that a prediction from the duality of a peculiar momentum-dependet scaling of the Fermionic self-energy is able to very accurately model a recently-observed feature of the spectral function measured in high-quality photoemission-spectroscopy measurements on a cuprate.