+2 votes
asked by (1.1k points)

Is there a method that can accept an MPS (where the indices have been defined with quantum numbers) and return the total quantum number of that state, or even the individual quantum number values of the ITensor objects within that state? Similarly, is there a method that can accept an MPO and return its QN flux? I know that you can compute this manually, but it would be nice to have a method that can make sure that it is doing what I intend it to do. I couldn't find such methods when looking through the Julia code on the GitHub page, but it's possible I just missed them.

1 Answer

+2 votes
answered by (51.6k points)

Yes, if you call flux(psi) where psi is an MPS or flux(H) where H is an MPO it will tell you the total flux of that MPS or MPO.

Best,
Miles

commented by (1.1k points)
Thank you so much! Just to be sure, this method works for MPSs and MPOs, but is there not a way to find the QN values for the individual tensors? I ask because it says, "For a tensor network such as an MPS or MPO, the flux is the sum of fluxes of each of the tensors in the network."
commented by (51.6k points)
Yes, you can call flux on each tensor individually too. Actually the implementation of `flux(::MPS)` is just a loop over the tensors of the MPS, summing the QN's together.
commented by (1.1k points)
OK, thank you so much!
commented by (51.6k points)
I think the version of `flux` taking an ITensor just isn't documented, currently. We need to do that!
Welcome to ITensor Support Q&A, where you can ask questions and receive answers from other members of the community.

Formatting Tips:
  • To format code, indent by four spaces
  • To format inline LaTeX, surround it by @@ on both sides
  • To format LaTeX on its own line, surround it by $$ above and below
  • For LaTeX, it may be necessary to backslash-escape underscore characters to obtain proper formatting. So for example writing \sum\_i to represent a sum over i.
If you cannot register due to firewall issues (e.g. you cannot see the capcha box) please email Miles Stoudenmire to ask for an account.

To report ITensor bugs, please use the issue tracker.

Categories

...