(Location: Physics C05 (UP-PHYS-C05), School of Physics and Astronomy, University Park Campus)
Details of the programme can be found below.
For further information please contact Jorma Louko .
Steffen Gielen (Sheffield)
Ben Graham (York)
Robert Laugwitz (Nottingham)
Patricia Ribes Metidieri (York)
11:00 - 11:30 Welcome
11:30 - 12:30 Steffen Gielen
12:30 - 14:00 Lunch
14:00 - 14:45 Patricia Ribes Metidieri
14:45 - 15:30 Robert Laugwitz
15:30 - 16:00 Ben Graham
16:00 - 17:00 Informal discussions
Title: Entanglement in Quantum Fields: From the Early Universe to the Lab
Abstract: In trying to formulate quantum theories of gravity, we need to agree on which basic principles are expected as fundamental in the new theory. One of the most important properties of standard quantum mechanics is unitarity of time evolution. Quantum gravity is often expected or required to be unitary in some sense, although it is less clear what that means. I will explore different ways in which unitarity can be realised in quantum models of cosmology and black holes, and show that certain notions of unitarity (using the time coordinate of unimodular gravity) can lead to generic resolution of classical singularities, replacing them by quantum transitions from a past universe or into a future white hole.
Title: Entanglement in Quantum Fields: From the Early Universe to the Lab
Abstract: Entanglement, as Schrödinger famously highlighted, is a defining feature of quantum theory. While it is a fragile resource in finite-dimensional systems, in quantum field theory it is ubiquitous, appearing already in the vacuum state.
In this talk, I will present an operational framework to characterize the spatial distribution of entanglement in quantum field theory, motivated by the limitations of realistic measurements. The framework provides a geometric description of operationally accessible entanglement using localized observables and Gaussian Quantum Information theory. I will apply it to two physically relevant settings.
First, I will show that during cosmic inflation, entanglement between localized modes and the rest of the field is highly delocalized and effectively acts as noise for correlations within the observable universe, helping explain the apparent emergence of classical behavior in cosmological perturbations. Finally, I will discuss how the same ideas enable experimentally accessible probes of vacuum entanglement in analogue gravity systems, potentially within reach of current experiments.
Title: Rigid monoidal 2-categories from non-semisimple braided tensor categories
Abstract: Fusion categories, and more generally tensor categories, have a wealth of applications in topology and mathematical physics. Recently, a theory of fusion 2‑categories, generalizing that of fusion categories to monoidal 2‑categories, has been developed. It is established that fusion 2‑categories have strong rigidity properties: all objects have duals and all 1‑morphisms have adjoints. Semisimple module categories over a braided fusion category provide a broad class of examples of fusion 2‑categories.
In this talk, I will report on a new class of perfect module categories, a subclass of exact module categories over a braided tensor category. These give monoidal 2‑categories that retain the same rigidity properties as fusion 2‑categories but are locally non‑semisimple. This is joint work in progress with Azat Gainutdinov (Tours).
Title: Measurement Schemes for Interacting Quantum Fields
Abstract: A local, covariant description of the measurement process in relativistic quantum field theory was recently developed by Fewster and Verch. In this framework, a target quantum field theory is measured indirectly by means of a coupling to a probe field theory in a compact region of spacetime. For field theories admitting a description by a Lagrangian, the coupled theory differs from the uncoupled one the addition of an interaction term. To date, concrete implementations of the Fewster-Verch framework have been exemplified by an uncoupled theory of free scalar fields, with a coupled theory described by a linear interaction term. In this talk, we discuss how methods of perturbative algebraic quantum field theory can be applied to analyse measurement schemes for interacting quantum fields and how these techniques allow for explicit computation of quantities of interest.
Some general info is available here: https://www.nottingham.ac.uk/about/visitorinformation/mapsanddirections/universityparkcampus.aspx
The talks will take place in the lecture theatre UP-PHYS-C05 in the School of Physics and Astronomy. The latter is located directly next to the School of Mathematical Sciences. See also the map below: