Mathematical theory for topological insulators

Click For Summary

Discussion Overview

The discussion centers around the mathematical theory related to topological insulators (TIs), exploring the connections between topology, fiber bundles, and K-theory in the context of physics. Participants seek to understand how these mathematical concepts apply to the physical properties of TIs and related phenomena like the quantum Hall effect.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant expresses curiosity about the relationship between topological insulators and mathematical theories, specifically fiber bundles and K-theory, and seeks clarification on what constitutes trivial and non-trivial fiber bundles.
  • Another participant suggests that the nontrivial topology in TIs and the integer and fractional quantum Hall effects (IQHE/FQHE) is represented in the Bloch wave function, emphasizing the role of the Berry phase and quantization conditions.
  • There is a mention of the Chern number for the quantum Hall effect and the Z2 invariant for topological insulators, with a note that a globally valid wave function cannot be defined in topologically nontrivial systems.
  • A request for specific book titles is made, as one participant is unable to find the recommended literature on Google.
  • Further recommendations include studying various models and theories in a specific order, starting from the integer quantum Hall effect, progressing through the Haldane model for graphene, and eventually addressing three-dimensional TIs and topological superconductors.
  • One participant advises that the fractional quantum Hall effect should be approached last due to its complexity.

Areas of Agreement / Disagreement

The discussion reflects a range of viewpoints and suggestions regarding the mathematical underpinnings of topological insulators, with no consensus reached on the specific connections or the best approach to learning about these topics. Participants share differing perspectives on the importance and sequence of study without resolving these differences.

Contextual Notes

Participants reference various mathematical concepts and models without fully establishing definitions or assumptions, indicating a reliance on prior knowledge of topology and condensed matter physics. The discussion includes unresolved aspects regarding the application of these theories to physical systems.

taishizhiqiu
Messages
61
Reaction score
4
I have been learning topological insulators recently, and I become more and more curious about the link between topological insulators and mathematical theory these days.

I know topological insulators have something to do with fiber bundles and K-theory. I have a relatively good background of undergraduate topology and recently I have read some introduction about fiber bundles and K-theory. What is missing in my mind is the link between math and physics. That is, what exactly do we regard as fiber bundles and classify them as trivial and non-trivial?

Can someone kindly give me the answer or some references?
 
Physics news on Phys.org
Look at the books by Fradkin, Bernevig/Hughes, and Wen.

When you talk about TIs or the IQHE/FQHE, the nontrivial topology is in the Bloch wave function. You are looking at the Berry phase of this wave function and the fact that the wf must be single valued gives you some quantization condition. For the QHE you get the chern number, for TIs you get a Z2 invariant. If the system is topologically nontrivial, you cannot define a wf that is valid globally. This is the same idea as the Dirac monopole or Aharanov Bohm effect
 
radium said:
Look at the books by Fradkin, Bernevig/Hughes, and Wen.

When you talk about TIs or the IQHE/FQHE, the nontrivial topology is in the Bloch wave function. You are looking at the Berry phase of this wave function and the fact that the wf must be single valued gives you some quantization condition. For the QHE you get the chern number, for TIs you get a Z2 invariant. If the system is topologically nontrivial, you cannot define a wf that is valid globally. This is the same idea as the Dirac monopole or Aharanov Bohm effect
Can you give me names of the books? I can't find them on google.
 
Field theories of condensed matter, topological insulators and topological superconductors, and quantum field theory of many body systems: from the origin of sound to an origin of light and electrons. The first two have chapters explicitly on Z2 TIs and TSCs. The second has a chapter or two on the IQHE and FQHE and a chapter about topology in condensed matter. It does not explicitly discuss Z2 TIs but does discuss things you should know about them.

In general, the best way to learn about these states is to start from the integer QHE, then go to the Haldane model for graphene, then go to the KM model in graphene (it is good to read that paper and a few of the ones after that) then go to 3D TIs/FKM model. Then you can learn about TSCs (the mapping from the quantum ising model to the majorana chain is very important).

If you want to learn about the FQHE, I would save that for last, it is incredibly subtle.
 

Similar threads

  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 31 ·
2
Replies
31
Views
3K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 20 ·
Replies
20
Views
10K
Replies
5
Views
4K
  • · Replies 4 ·
Replies
4
Views
5K
  • · Replies 11 ·
Replies
11
Views
4K