Speaker: Massimo D’Elia (Dipartimento di Fisica – UNIPI and INFN)
Title: “Quantum Computation and Fundamental Interactions”
Abstract:
Our present description of Fundamental Interactions is based on Quantum Field Theories, which are computable analytically only within certain approximation schemes, like perturbation theory. Many relevant natural phenomena, however, involve a regime where such schemes break down: then, most of our predictive power relies on numerical computations. Which computer is capable of computing a Quantum Field Theory? It is possible, in principle, to make use of a classical computer: this is done, usually, within the path-integral formulation of Quantum Mechanics, developed by Richard Feynman. That works in many cases, yet the computation becomes NP-hard for some important applications, where one has to face a complex path-integral measure (sign problem): this is why, for instance, we can compute the origin of the visible mass of the Universe, but at the same time we cannot predict the properties of matter inside a neutron star. In these cases, since we are dealing with a quantum theory, we’d better make the simulation itself quantum mechanical, as suggested by Feynman again: that would indeed solve the problem at its root. Even if the required quantum computing resources are still far from being achieved, it is useful and timely to test the possible quantum algorithms on simplified models.