Objective features in quantum states

One of the key features of quantum mechanics is that any superposition of quantum states is in itself a legitimate quantum state. This has far reaching consequences, and is behind the stark difference in behaviour between quantum and classical systems. In particular, quantum systems are not -unlike classical ones- intrinsically objective, that is, different observers are not always able to agree on the properties of the system. Understanding the conditions for objectivity in quantum states is therefore key to address the wider issue of the quantum-to-classical transition. Here, we discuss several aspects of quantum objectivity, and in particular subtleties that arise to the definitions of objectivity whenever non-ideal scenarios are taken into account. We first explore the emergence of objectivity in novel open system dynamics. We then discuss the relations between different methods to quantify objectivity, prove their non-equivalence and the implications that this entails. Finally, we provide proof-of-principle evidence on the reproducibility of non-trivial objective states on quantum computers.