Good morning,
Next week's seminar talk will be by Norbert Schuch.
The seminar will be on March 8 on Hoenggerberg:
Tuesday, March 8, 17:00, HIT J 51.
Best regards,
Stefan
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Classifying quantum phases using Matrix Product States and PEPS
>
> joint work with D. Perez-Garcia and I. Cirac
>
> We apply the framework of Matrix Product States (MPS) and their parent
> Hamiltonians to the classification of gapped quantum phases in
> one-dimensional systems and beyond. We discuss both the case of systems
> with unique ground states and with degenerate ground states, i.e.,
> symmetry breaking, both in the absence and in the presence of symmetries.
> We find that without symmetries, all systems (up to ground state
> degeneracy) are in the same phase. If symmetries are imposed, the
> classification is based on the different types of projective
> representations of the symmetry group, together with its permutation
> action on the symmetry broken ground states. We also discuss how to
> extend our results to two dimensional systems using Projected Entangled
> Pair States (PEPS), and show that one cannot expect the same type of
> symmetry protection as in one-dimension. As a central tool, we introduce
> the isometric form of an MPS which gives a rigorous framework for studying
> phases using renormalization fixed points, without a need to actually
> renormalize the system.
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