Define the projection operators using ITensors function ITensors.op!(Op::ITensor, ::OpName"Pup", ::SiteType"S=1/2", s::Index) Op[s'=>1,s=>1] = 1.0 end function ITensors.op!(Op::ITensor, ::OpName"Pdn", …

Hi, so I found the problem. The norm of the state you are computing expected values within is zero. This is because the spin you act Pdn on is exactly in the up state, so projecting it to be down makes the state go to zero (even though the individual MPS tensors might have non-zero parameters in som…

Thank you for the suggestion. I formatted it.

Hi, so I tried running your code but got an error around the line psi_temp = MPS(s,"Up"). What version of ITensors are you using, and can you please make sure you are upgraded to the latest version? If you do, does it fix the issue you are seeing?

Hi Miles, I am sorry about this. I forgot to add N = 100 s = siteinds("S=1/2",N) in the code so you got error in line psi_temp = MPS(s,"Up"). I fixed the code. I am using version ITensors v0.3.51. I am still getting NaN as the output for all sites when I do expect(psin,"Sz") where psin=apply(Pd…

Applying down projection operator to Up spin site gives psi with "Sz" = NaN instead of 0.

ITensor Julia Questions

mtfishman November 14, 2023, 2:45pm 2

Could you format your code? See Please Read: Make It Easier to Help You.

Topic		Replies	Views
applying a local reset gate to an mps ITensor Julia Questions	3	253	October 10, 2023
Problem of projector calculation for a complex MPS ITensor Julia Questions	2	90	February 13, 2025
Expectation value of a local operator acting on a MPS ITensor C++ Questions	6	805	July 26, 2022
Projection operators of complex Hilbert space ITensor Julia Questions mps , mpo	0	202	November 29, 2023
Error by computing expectation value of Sy in S=1/2 and S=1 ITensor Julia Questions	1	506	November 25, 2022

Applying down projection operator to Up spin site gives psi with "Sz" = NaN instead of 0.

Related topics