Search found 25 matches

by amankumar
17 Feb 2021, 11:47
Forum: HowTos and FAQ for TeNPy
Topic: Excited states using tenpy
Replies: 10
Views: 248

Re: Excited states using tenpy

Can one provide the periodic boundary condition of own choice, like of different genus. But now I am in interested to know how bc_shift works, so that there will be spiral like boundary condition not simple ring attached in x direction.

Thanks

by amankumar
12 Feb 2021, 12:08
Forum: HowTos and FAQ for TeNPy
Topic: Excited states using tenpy
Replies: 10
Views: 248

Re: Excited states using tenpy

Thanks for the update, I got it. Does add_onsite also support this array data type for strength? May be, Now I am asking an offset question of this thread, actually I was interested in to provide the different types of boundary condition in y direction for a cylinder. I want a spiral winding of chai...
by amankumar
10 Feb 2021, 10:10
Forum: HowTos and FAQ for TeNPy
Topic: Excited states using tenpy
Replies: 10
Views: 248

Re: Excited states using tenpy

Thanks a lot! I have another basic question related to model interaction strength. Is there a way to put different interaction strength at each vertex in topic code model, like can I provide a array of strength parameter instead of just Jv. self.add_multi_coupling(-Jv, [('Sigmax', [0, 0], 1), ('Sigm...
by amankumar
07 Feb 2021, 19:52
Forum: HowTos and FAQ for TeNPy
Topic: Excited states using tenpy
Replies: 10
Views: 248

Re: Excited states using tenpy

I still did not get the code, can you explain bit more. psi0 = MPS.from_product_state(...) states = dmrg_params['orthogonal_to'] = [] So, here we create an initial MPS and then in next line I am confused, does it just add another parameter or routine orthogonal_to in dict dmrg_params. for i in range...
by amankumar
05 Feb 2021, 09:08
Forum: HowTos and FAQ for TeNPy
Topic: Excited states using tenpy
Replies: 10
Views: 248

Re: Excited states using tenpy

Thanks Johannes 1.) I guess the code line psi = psi0.copy() should be before the for loop, otherwise it will keep using the initial matrix product state(that is psi0 copy). 2.) Also it give me an error saying: File "/home/aman/tenpy-master2/tenpy-master/examples/tenpy/algorithms/mps_sweeps.py&q...
by amankumar
01 Feb 2021, 15:08
Forum: HowTos and FAQ for TeNPy
Topic: Excited states using tenpy
Replies: 10
Views: 248

Excited states using tenpy

Hi I am interested in to know the excited states of Kiteav's Toric code model. I was going through the documentation to understand how to use it. Can you briefly explain more how to use tenpy for evaluating excited states for lets say first two excited states only. Here is my short code, where I am ...
by amankumar
04 Nov 2020, 11:43
Forum: HowTos and FAQ for TeNPy
Topic: state overlap(probability)
Replies: 7
Views: 726

Re: state overlap(probability)

Thank you for the response. I have another difficulty in this part, I saw source code of get_rho_segment , where sorting is done for segment sites. So If I am evaluating \rho_{ij} , where index i>j , and I will transform it into a 4\times 4 matrix. So, now I am interested in \rho_{ji} density matrix...
by amankumar
01 Nov 2020, 16:00
Forum: HowTos and FAQ for TeNPy
Topic: state overlap(probability)
Replies: 7
Views: 726

Re: state overlap(probability)

Can I see my two site reduced density matrix in this below format, where I can get to know about each elements of the matrix. \begin{matrix} c_{\uparrow_i\uparrow_j\uparrow_i\uparrow_j} & c_{\uparrow_i\uparrow_j\uparrow_i\downarrow_j} & c_{\uparrow_i\uparrow_j\downarrow_i\uparrow_j} &c_{...
by amankumar
26 Oct 2020, 15:41
Forum: HowTos and FAQ for TeNPy
Topic: state overlap(probability)
Replies: 7
Views: 726

Re: state overlap(probability)

1.) Is there a way to get full \rho_i in matrix form or do I have to calculate each matrix element separately as you suggested above. 2.) Also can I calculate this quantity \langle \Psi | \downarrow_i\rangle , as one way I think of by taking square root of corresponding density matrix element, but t...
by amankumar
26 Oct 2020, 05:40
Forum: HowTos and FAQ for TeNPy
Topic: state overlap(probability)
Replies: 7
Views: 726

state overlap(probability)

Hi I want to know, is there a way to calculate probability to find particle at any site i in up (or down) state? Like if I have a state |\Psi> in MPS form and I want to evaluate this quantity <\Psi|down_i> , where |down_i> is linear combination of all simple basis state where at site i it is down an...
by amankumar
21 Oct 2020, 18:23
Forum: HowTos and FAQ for TeNPy
Topic: Symmetries Of lattice
Replies: 10
Views: 1093

Re: Symmetries Of lattice

Yes while copying code here, I missed that term, which I have updated now. But still I did not understood this distinct behaviour of ground state with or without parity.
Also, how to implement total Sz conserve symmetry here?
by amankumar
21 Oct 2020, 17:49
Forum: HowTos and FAQ for TeNPy
Topic: Symmetries Of lattice
Replies: 10
Views: 1093

Re: Symmetries Of lattice

Yes I am considering Ferromagnetic Heisenberg model on hexagonal lattice. Here is my code from tenpy.algorithms import dmrg import numpy as np from mps import MPS from tenpy.models.lattice import Lattice, get_order, _parse_sites,Honeycomb from tenpy.networks.site import SpinHalfSite from tenpy.model...
by amankumar
21 Oct 2020, 15:10
Forum: HowTos and FAQ for TeNPy
Topic: Symmetries Of lattice
Replies: 10
Views: 1093

Re: Symmetries Of lattice

Thanks That is fine, when parity is conserved, state is in all up state plus down state, which is confirmed by zero expectation vale of Sz on a site. And in other case, when I turn off parity, I get state to be in all up configuration, confirmed by "one" expectation value of Sz on a site. ...
by amankumar
19 Oct 2020, 09:00
Forum: HowTos and FAQ for TeNPy
Topic: Symmetries Of lattice
Replies: 10
Views: 1093

Re: Symmetries Of lattice

Hi
If you need more details, or did not understood my question, please let me know.
Thanks
by amankumar
14 Oct 2020, 21:34
Forum: HowTos and FAQ for TeNPy
Topic: Symmetries Of lattice
Replies: 10
Views: 1093

Re: Symmetries Of lattice

Thanks it works fine, but only for small bond dimension. I have another conceptual question in dmrg, I was simulating ferromagnetic heisenberg model using tenpy, and evaluated ground state entanglement entropy for some subsystem. I got Log(2) as answer, as this is obvious ground state preserves spin...
by amankumar
12 Oct 2020, 19:30
Forum: HowTos and FAQ for TeNPy
Topic: Symmetries Of lattice
Replies: 10
Views: 1093

Symmetries Of lattice

Hi I wanted to evaluate entanglement entropy for a segment of sites with function entanglement_entropy_segment(). But this can not take more than or equal 12 sites as memory issue. Can I exploit lattice symmetries like translation one using tenpy package, and can extend my segment size to more than ...
by amankumar
05 Jun 2020, 20:01
Forum: HowTos and FAQ for TeNPy
Topic: entanglement_entropy_segment doubt
Replies: 13
Views: 7266

Re: entanglement_entropy_segment doubt

Thank you for the update to allow torus-boundary conditions. And as you pointed I implemented it on Toric Code model and bond dimension is squared as compared to infinite cylinder. 1.) But now I am getting back to my old thread question. I am trying to evaluate entanglement for a system size L_x=L_y...
by amankumar
04 Jun 2020, 09:43
Forum: HowTos and FAQ for TeNPy
Topic: Irregular lattice site removing doubt
Replies: 4
Views: 1473

Re: Irregular lattice site removing doubt

I am sorry for posting question in "Papers using TeNPy", I don't remember how did I posted it there. I tried to use Irregular Lattice for Toric Code model by removing those sites which do not belong to any Plaquette of the original square lattice. I am getting an unusual error. Can you hel...
by amankumar
02 Jun 2020, 18:38
Forum: HowTos and FAQ for TeNPy
Topic: Irregular lattice site removing doubt
Replies: 4
Views: 1473

Irregular lattice site removing doubt

In the new released you updated the Irregular lattice site where one can remove some sites. I read the documentation but did not understood how to specify the sites which one wants to remove. I considered Toric code model(L_x=3,L_y=3) and wanted to remove all sites(18,19,20,21,22,23) which are not s...
by amankumar
18 May 2020, 18:00
Forum: HowTos and FAQ for TeNPy
Topic: entanglement_entropy_segment doubt
Replies: 13
Views: 7266

Re: entanglement_entropy_segment doubt

I understand that, I deliberately tried to change the lattice basis vector and order in Honeycomb lattice. 1.) How to change the model such that it supports toroidal boundary condition, as you suggested in earlier post. Can you guide me for this your famous toric code example. 2.) I tried to impleme...
by amankumar
16 May 2020, 10:21
Forum: HowTos and FAQ for TeNPy
Topic: entanglement_entropy_segment doubt
Replies: 13
Views: 7266

Re: entanglement_entropy_segment doubt

Thank you for such a beautiful explanation, 1.) I understand by changing the winding direction, bond dimensions changes depending on the interaction. As you said one can try different geometry(changing the winding) and try to see MPS entropy, Is there another possible geometry possible for square la...
by amankumar
14 May 2020, 19:17
Forum: HowTos and FAQ for TeNPy
Topic: entanglement_entropy_segment doubt
Replies: 13
Views: 7266

Re: entanglement_entropy_segment doubt

Can you explain a bit more your second point. Of course entanglement entropy is basis dependent, if you write the Hamiltonian in the basis of exact eigenstate of model, then in that basis ground state would be pure state. But I do not understand how the bond dimension is reduced in Dual Square latti...
by amankumar
13 May 2020, 17:40
Forum: HowTos and FAQ for TeNPy
Topic: entanglement_entropy_segment doubt
Replies: 13
Views: 7266

Re: entanglement_entropy_segment doubt

Thank You for the clarification, 1.)Does tenpy also implement toroidal boundary condition ? 2.) I have another question not related to the thread, Suppose I have a model whose ground state is highly entangled, and it requires huge number of chi_max. So can you suggest me some way reduce chi_max, or ...
by amankumar
06 May 2020, 15:35
Forum: HowTos and FAQ for TeNPy
Topic: entanglement_entropy_segment doubt
Replies: 13
Views: 7266

Re: entanglement_entropy_segment doubt

Thank you for your clarification. But I am concerned about one point, that whether these two operations of entanglement entropy gives the same answer or not for a same subsystem. So I did a check for a given example of Toric Code Model. Here I took Lx=2,Ly=3 and evaluated ent. entropy for same subsy...
by amankumar
22 Apr 2020, 21:01
Forum: HowTos and FAQ for TeNPy
Topic: entanglement_entropy_segment doubt
Replies: 13
Views: 7266

entanglement_entropy_segment doubt

Hey I wanted to evaluate entanglement entropy for a subsystem given by sites in segment parameter in entanglement_entropy_segment function. It should give entropy of this subsystem meaning just one numeric number. But in return I am getting array of entropies. I completely don't understand what each...