Quantum reference frames: A relational approach to states, symmetry, and covariance - Časlav Brukner

In classical physics, reference frames are modeled by rods and clocks, providing a fixed structure for measuring space and time. In quantum mechanics, however, these measuring devices can themselves be quantum systems, fundamentally altering our understanding of superposition, causal order, and symmetry. This talk will provide an overview of quantum reference frames (QRFs) and their implications for fundamental physics. We will explore how QRFs generalize classical coordinate transformations by treating rods and clocks as quantum objects, leading to new insights into the relativity of quantum superpositions, entanglement, and event localization, as well as their connection to gravity and general covariance. Finally, I will discuss potential experimental realizations and key open challenges in this emerging field.