We are celebrating this year the centenary of quantum mechanics, the culmination of discoveries made at the beginning of the last century, among which Bohr's model of the hydrogen atom played an essential role. This model justified Rydberg's formula, which empirically described the spectrum of this atom and predicted the existence of highly excited atomic states with remarkable exaggerated properties (huge size of the electron orbits, long life span, intense coupling with microwave fields and very strong interactions between these atoms at quasi-macroscopic distances). The experimental study of these atoms - particularly of the circular Rydberg states of maximum angular momentum described by Bohr - began half a century ago with the development of tunable lasers. Rydberg atoms have played a central role in the development of Cavity Quantum Electrodynamics, in experiments which have tested the principles of quantum mechanics by realizing in the laboratory some of the Gedankenexperiment conceived a hundred years ago by the founders of quantum physics, among which the famous “Schrödinger cat” experiment. More recently, Rydberg atoms have been used in quantum simulation studies where, trapped in optical lattices, they are individually controlled, manipulated and detected by laser light. The physics of Rydberg atoms is thus closely associated with the history of quantum physics from its origins to its most recent developments, with the promise of more exciting advances in the years to come.

Major improvements in the theoretical aspects of Cosmology have been possible in recent years due to QFT-inspired methods, such as the effective field theory of large-scale structure (EFTofLSS). In this talk, I will explore further connections between high-energy physics and cosmology. I will present a systematic approach to renormalizing the galaxy bias parameters using path integrals and a finite cutoff scale Λ. I will derive the differential equations of the Wilson-Polchinski renormalization group that describe the evolution of the finite-scale bias parameters with Λ, analogous to the β-function running in QFT. I will then discuss how the RG-flow of EFTofLSS can lead to improvements in the extraction of cosmological parameters and also serve as a tool for sanity checks.