Posmom: the unobserved observable

Abstract

The position-momentum dot product (‘posmom’) s = r.p of a particle is a quantum mechanical observable and we have recently shown that its probability density S(s) can be computed efficiently from the positionspace wavefunction ψ(r) of a particle. In this lecture, I will show how the posmom density is related to the position density ρ(r) and the momentum density Π(p) and I will argue that S(s) yields insight into the nature of electronic trajectories. Finally, I will propose that electron posmometry can potentially provide information that is inaccessible from conventional diffraction or momentum methods