Speaker:Erik Aurell 

Title: 
One possible solution to Hawking's black hole information paradox is to postulate 
that a pure quantum state of a collapsing object
evolves unitarily to a pure quantum black hole, which in turn evolves unitarily to a 
pure state of Hawking radiation, when all the
black hole will have radiated away. By assumption the final state then involves only 
known physics, though of very high-dimensional states.
We idealize (simplify) by supposing that all the Hawking particles are photons.

The constraint that a total state over some set of photonic modes is pure while all 
the marginals are thermal is a quantum
marginal problem. If such problems can be solved or not depend in a surprisingly 
simple way on the properties of the marginals, i.e.
on the mode temperatures. I will discuss what implications these and related 
developments may have for the information return scenario.

The talk is partly based on joint work with Paweł Horodecki and Michał Eckstein, 
JCAP01(2022)014, and partly on work in preparation
with Mario Kieburg, Lucas Fabian Hackl, Paweł Horodecki and Robert H. Jonsson.

Presented previously: Sommerfeldt theory colloquium LMU Munich April 2023