Causality and Information Flow in Quantum Protocols

          @misc{ pirsa_PIRSA:08100045,
            doi = {10.48660/08100045},
            url = {https://pirsa.org/08100045},
            author = {Abramsky, Samson},
            keywords = {Quantum Foundations},
            language = {en},
            title = {Causality and Information Flow in Quantum Protocols},
            publisher = {Perimeter Institute},
            year = {2008},
            month = {oct},
            note = {PIRSA:08100045 see, \url{https://pirsa.org}}
          }
          

Abstract

In recent work with Bob Coecke and others, we have developed a categorical axiomatization of quantum mechanics. This analyzes the main structural features of quantum mechanics into simple and general elements, which admit an elegant diagrammatic representation. This enables an illuminating and effective analysis of quantum information protocols and computational structures. One aspect which is brought to light in this analysis is that protocols such as teleportation use entanglement to achieve a logical information flow which has an apparent retro-causal (or even `backward-in-time\') component. However, there is also a physical or operational description of the same systems, based on an abstract structural characterization of quantum measurements, which is entirely causally consistent. The systematic relationship between these two descriptions suggests a novel perspective on the flow of time and information in the quantum realm.