Quantum Knowledge

          @misc{ pirsa_PIRSA:09100089,
            doi = {10.48660/09100089},
            url = {https://pirsa.org/09100089},
            author = {Blume-Kohout, Robin},
            keywords = {Quantum Foundations},
            language = {en},
            title = {Quantum Knowledge},
            publisher = {Perimeter Institute},
            year = {2009},
            month = {oct},
            note = {PIRSA:09100089 see, \url{https://pirsa.org}}
          }
          

Abstract

It's been suggested that "decoherence explains the emergence of a classical world". That is, if we believe our world is quantum, then decoherence can explain why it LOOKS classical. Logically, this implies that without decoherence, the world would not look classical. But... what on earth WOULD it look like? Human beings seem incapable of directly observing anything "nonclassical". I'll show you how a hypothetical quantum critter could interact with, and learn about, its world. A quantum agent can use coherent measurements to gain quantum knowledge about its surroundings. They can use that quantum knowledge to accomplish tasks. Moreover, clumsy classical critters (like me!) could identify quantum agents (and prove that they are using quantum knowledge), because they outperform all classical agents. I'll explain the remarkable new perspective on quantum states that comes from thinking about quantum knowledge, and I'll argue that it's a useful perspective by showing you two concrete applications derived from it.