String Theory Journal Club

We treat a new mechanism for ergodicity breaking in one dimensional quantum many body systems. We treat spin chains with local Hamiltonians, which have a special fine tuned form: there is interaction in the system, nevertheless the models have a large non-commutative symmetry algebra, generated by Matrix Product Operators (MPO). Meanwhile, the models are NOT integrable, and not exactly solvable. The exotic symmetries cause exact degeneracies in the finite volume spectrum, leading to a breakdown of thermalization. The mechanism we treat is a special type of "Hilbert space fragmentation''. It appears that our models are the first ones, where non-commutative MPO symmetries are found, such that the models are not integrable. Transmisja online: https://uw-edu-pl.zoom.us/j/94797623941, meeting ID: 947 9762 3941.