Matrix product symmetries and breakdown of thermalization from hard rod deformations

We construct families of exotic spin-1/2 chains using a procedure called ``hard rod deformation’'. We treat both integrable and non-integrable examples. The models possess a large non-commutative symmetry algebra, which is generated by matrix product operators with fixed small bond dimension. The symmetries lead to Hilbert space fragmentation and to the breakdown of thermalization. As an effect, the models support persistent oscillations in non-equilibrium situations. Similar symmetries have been reported earlier in integrable models, but here we show that they also occur in non-integrable cases.