Symmetry protected topological orders and the group cohomology of their symmetry group
Xie Chen, Zheng-Cheng Gu, Zheng-Xin Liu, and Xiao-Gang Wen
Introduced group cohomology theory into condensed matter physics to describe
short-range entangled phases with symmetry for interacting bosons.
Constructed two quantum spin models on a lattice which gives rise to emergent
gravitons (one with ω = k and the other with ω = k^3 dispersion).
After 6 years, many journals (Science, PRL, PRB, NJP, JHEP, NPB), and about
30 exchanges, one of our linear quantum gravity papers
finally get published in Nucl. Phys. B. Next problem: how non-linear quantum
gravity can emerge from some lattice models.
The referee reports and our replies represent detailed discussions between
parties who have different points of view on quantum gravity: emergence point
of view vs geometry/gauge point of view. The exchange of opinions is important
and helpful for the development of the difficult field of quantum gravity.
So, I would like to share those exchanges with the researchers in the field.
Following Hong Liu's suggestion, we moved the long introduction of the long
paper to appendix and resubmited the long paper to
NPB. This time, it was accepted [:-)
Photons and electrons as emergent phenomena
Michael A. Levin and Xiao-Gang Wen Rev. Mod. Phys.77, 871-879 (2005),
String-net condensation provides a way to unify light and electrons.
String-net condensation: A physical mechanism for topological phases
Michael Levin and Xiao-Gang Wen Phys. Rev. B71, 045110 (2005).
Introduced tensor category theory into condensed matter physics to describe
long-range entangled phases (ie topologically ordered phases) for interacting