Seminarium Fizyki Materii Skondensowanej

Exact solutions are available for a number of models of great interest in quantum mechanics, including some with promise for quantum information processing. In practice however, such formal exact solutions are challenging to translate into detailed quantitative predictions: any connection between the underlying system and its measurable quantities relies on knowing how physical operators and model (eigen)states "talk" to each other, this being quantitatively encoded in operator matrix elements. If obtained, these can then be "cooked" into correlation functions via Lehmann representations, but summing contributions is generally challenging.This talk will focus on the matrix elements themselves. For given observables, their dependence on states and excitations will be discussed, as well as how sensitive they are to various modifications of the details of the states. An approach towards regularizing microscopic states into field theory-like entities will be discussed, with potential use in computing correlations and managing (numerical) renormalization approaches to in- and out-of-equilibrium situations.