Quantum orders in an exact soluble model

2003
5 pages
Published in:
  • Phys.Rev.Lett. 90 (2003) 016803
e-Print:

Citations per year

20032009201520212025010203040
Abstract: (arXiv)
We find all the exact eigenstates and eigenvalues of a spin-1/2 model on square lattice: H=16giSiySi+xxSi+x+yySi+yxH=16g \sum_i S^y_i S^x_{i+x} S^y_{i+x+y} S^x_{i+y}. We show that the ground states for g<0g<0 and g>0g>0 have different quantum orders described by Z2A and Z2B projective symmetry groups. The phase transition at g=0g=0 represents a new kind of phase transitions that changes quantum orders but not symmetry. Both the Z2A and Z2B states are described by Z2Z_2 lattice gauge theories at low energies. They have robust topologically degenerate ground states and gapless edge excitations.
Note:
  • 4 pages, RevTeX4, More materials on topological/quantum orders and quantum computing can be found in http://dao.mit.edu/~wen