Speaker
Description
A central question in the study of quantum information theory in the presence of symmetries concerns which properties of a system can be inferred by observers without access to the laboratory frame. We show how using a quantum system as a reference frame allows one to evade symmetry constraints, focusing on systems that can serve as quantum clocks. However, realistic quantum clocks cannot perfectly keep track of time. This might suggest that they are operationally less useful than ideal clocks. In this work, we explore whether the opposite is possible: are there any features that arise in the non-ideal case that are absent in the ideal one, thereby rendering non-ideal clocks more advantageous? We investigate this question within the framework of quantum reference frames that generalizes the extra-particle approach. Overall, we characterize the perspectives of quantum clocks through their operational capabilities, such as performing state tomography of an invariant state using relational observables.