COLLOQUIUM: 'The Physics of Can and Can’t': from the universal computer to the universal constructor

06 February 2020
Speaker: Chiara Marletto, University of Oxford
Abstract:
The theory of the universal quantum computer has brought us rapid technologicaldevelopments, together with remarkable improvements in how we understandquantum theory. There are, however, reasons to believe that quantum theory mayultimately have to be modified into a new theory: for instance, it will have tobe merged with general relativity, to incorporate gravity; and some claim thatit may be impossible to have quantum effects beyond a certain macroscopicscale. So what lies ahead of quantum theory, and of the universal quantumcomputer? To shed some light into these questions, we need a shift of logic inthe way things are explained. Specifically, one can adopt the approach wherethe basic assumptions are general principles about possible/impossibletransformations, rather than dynamical laws and initial conditions. Thisapproach is called constructor theory. I will describe its application to a handfulof interconnected problems, within information theory, thermodynamics, and evenquantum gravity. This ‘Physics of Can and Can’t' may be the first step towardsthe ultimate generalisation of the universal quantum computer, which vonNeumann called the 'universal constructor’.