Theory Discussion talk at the University of St Andrews
Theory Discussion, University of St Andrews, 20 February 2023.
Abstract:
“Neutron scattering has been one of the work horses of experimental materials research for
decades. However, it has been a long-held belief in the condensed-matter physics community
that neutron scattering can only yield incomplete information about the state of the system under
investigation. This is sometimes referred to as the ‘phase problem’ of neutron scattering: the fact
that a neutron-scattering cross-section is more like a photograph than a hologram. I will describe
and prove two theorems that suggest the situation may not be quite as bed in the case of a
broad class of quantum magnets. In fact, I shall argue that for such systems the diffuse
magnetic neutron scattering function can be used to completely determine the wave function
and the Hamiltonian. I will discuss the reasons for this as well as the limitations and speculate
on the ways this could change how we practice neutron scattering. I will also place these results
in the wider context of research into quantum information/quantum technology.”