Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Long-range entanglement (LRE) is the main feature of topological orders. The string-net condensation model was constructed to exhibit LRE.

But the many-body systems of such models do not look like any earthly materials at all but are closer to quantum gravity models. In quantum gravity, nobody sees the detailed structure beyond the Planck scale. But in condensed matter, the microscopic structures are "crystal" clear.

Then how can such strange models be used to explain LRE in laboratory materials?

share|cite|improve this question
up vote 4 down vote accepted

The many-body systems that give rise to LRE and string-net condensation are simply quantum spin models and they CAN look like earthly materials, such as the $J_1$-$J_2$ Heisenberg model on square lattice and the Heisenberg model on Kagome lattice for 1/2-spins. The many-body systems that give rise to LRE and string-net condensation DO have a "crystal" clear microscopic structures.

share|cite|improve this answer
Thank you! Yes, I remember you discussed about the $J_1\approx J_2$ model at KITPC. Now I realize that it is more of belief than logic. Personally I believe the bottom-up approach is more "helpful" to uncover novel materials (may or may not be "topological"), just like the case of topological insulators. – ChenChao Dec 29 '12 at 16:33

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.