New release: v0.6.1.

Search found 173 matches

by Johannes
17 Jun 2020, 20:03
Forum: HowTos and FAQ for TeNPy
Topic: Superposition of MPS with different total charge
Replies: 4
Views: 188

Re: Superposition of MPS with different total charge

To detect whether you have cat state, you should look at the eigenvalues of the transfermatrix, whether you get two eigenvalues exactly 1. If the ground state is a stripe, charge conservation can force it into superpositions. For that reason, I would also highly recommend to try using a larger (doub...
by Johannes
16 Jun 2020, 17:53
Forum: HowTos and FAQ for TeNPy
Topic: Superposition of MPS with different total charge
Replies: 4
Views: 188

Re: Superposition of MPS with different total charge

(I took the freedom to slightly edit your suggested code.)
by Johannes
16 Jun 2020, 17:49
Forum: HowTos and FAQ for TeNPy
Topic: Superposition of MPS with different total charge
Replies: 4
Views: 188

Re: Superposition of MPS with different total charge

May I ask why you want to create a superposition in the first place? Just for measurements? I don't really see a point for that. Or continuing some algorithm with another model which doesn't have the charge conservation? That would be more reasonable. Schollwoeck's 2011 review ("DMRG in the age of M...
by Johannes
16 Jun 2020, 05:29
Forum: HowTos and FAQ for TeNPy
Topic: Bipartitioning infinite MPS into 2 semi-infinite chains
Replies: 11
Views: 590

Re: Bipartitioning infinite MPS into 2 semi-infinite chains

I see. Sorry, if I appeared rude; I just wasn't sure what you wanted to do. I'd still recommend running DMRG to find the ground state, which gives you an MPS, and then just take that as initial state for the TEBD, as outlined below. On a side note, you can derive your model directly from the Nearest...
by Johannes
15 Jun 2020, 16:41
Forum: HowTos and FAQ for TeNPy
Topic: Bipartitioning infinite MPS into 2 semi-infinite chains
Replies: 11
Views: 590

Re: Bipartitioning infinite MPS into 2 semi-infinite chains

Why are you trying to do the time evolution? The paper you cited does *not* use TEBD, it uses DMRG! We define \theta = 2\pi t/T , assume adiabaticity and work in the instantaneous eigenbasis of H(\theta) . Hence, the charge transport becomes independent of the time scale T . "Adiabatically" implies ...
by Johannes
15 Jun 2020, 16:14
Forum: Algorithms
Topic: Toy code for np_conservervation
Replies: 1
Views: 152

Re: Toy code for np_conservervation

No, there is no toycode.

The idea is really just to keep track of the charges, which divides the tensor into smaller blocks, and multiply only the subblocks with compatible charges, re-implementing tensordot, eigh, ... to exploit the block structure.
by Johannes
12 Jun 2020, 06:19
Forum: HowTos and FAQ for TeNPy
Topic: Bipartitioning infinite MPS into 2 semi-infinite chains
Replies: 11
Views: 590

Re: Bipartitioning infinite MPS into 2 semi-infinite chains

Hang on - you're running DMRG to obtain ground states, right? What do you mean with the "evolution" steps? Why do you need the GroupedSite at all, if you're only running DMRG? Can you specify the hamiltonian? And the transfer matrix between which states? You might need to explicitly set charge_secto...
by Johannes
11 Jun 2020, 07:24
Forum: Releases
Topic: Release v0.6.0 and v0.6.1
Replies: 0
Views: 215

Release v0.6.0 and v0.6.1

Version 0.6.0 and 0.6.1 have been released. Before updating , please read at least the section incompatible changes of the changelog. Most important changes The release of v0.6.0 contains a major update of the documentation, which is now hosted by "Read the Docs" at https://tenpy.readthedocs.io/. If...
by Johannes
10 Jun 2020, 01:13
Forum: HowTos and FAQ for TeNPy
Topic: overlap of ground states at different parameters
Replies: 5
Views: 158

Re: overlap of ground states at different parameters

You're right of course. Okay, let me just say that I never tried it... You should probably still make sure that you follow the evolution with \theta adiabatically. In other words, use the result from the DMRG run with \theta as an initial guess for the \theta + \delta \theta DMRG, similarly as is do...
by Johannes
10 Jun 2020, 01:05
Forum: HowTos and FAQ for TeNPy
Topic: entanglement_entropy_segment doubt
Replies: 13
Views: 4006

Re: entanglement_entropy_segment doubt

So you try to use torus boundary conditions now? Just to make sure, the correct way to do this is (whith the standard toric code model as in the Repo): from tenpy.networks.mps import MPS from tenpy.algorithms import dmrg from tenpy.models.toric_code import ToricCode def example_run_TC(): model_param...