Composite quantum particles as ideal quantum clocks — operational approach to quantum aspects of time

          @misc{ pirsa_PIRSA:21060087,
            doi = {10.48660/21060087},
            url = {https://pirsa.org/21060087},
            author = {Zych, Magdalena},
            keywords = {Quantum Foundations},
            language = {en},
            title = {Composite quantum particles as ideal quantum clocks {\textemdash} operational approach to quantum aspects of time},
            publisher = {Perimeter Institute},
            year = {2021},
            month = {jun},
            note = {PIRSA:21060087 see, \url{https://pirsa.org}}
          }
          

Abstract

In general relativity time requires an operational description, for example, associated with the reading of an idealised clock following some world line. I will show that in quantum physics idealised clocks can be modelled as composite quantum particles and discuss what foundational insights into the notion of time is enabled by this approach. Moreover, since quantum particles do do not follow classical trajectories a question arises to which extent idealised quantum clocks can be associated with semi-classical paths — in analogy with quantum particles in Gaussian states being associated with semi-classical trajectories? I will show that for quantum clocks semi-classical propagation is not described by Gaussian but by a new class of quantum states derived from a new uncertainty inequality for configuration space rather than for phase space variables of the quantum clock.