Fernández González, CarlosSchuch, NorbertWolf, Michael M.Cirac, J.I.Pérez García, David2023-06-202023-06-202012-120031-900710.1103/PhysRevLett.109.26040https://hdl.handle.net/20.500.14352/42540We study Hamiltonians which have Kitaev's toric code as a ground state, and show how to construct a Hamiltonian which shares the ground space of the toric code, but which has gapless excitations with a continuous spectrum in the thermodynamic limit. Our construction is based on the framework of projected entangled pair states, and can be applied to a large class of two-dimensional systems to obtain gapless "uncle Hamiltonians."engjournal articlehttp://prl.aps.org/pdf/PRL/v109/i26/e260401http://www.aps.org/open access51Toric codeMatemáticas (Matemáticas)12 Matemáticas