when using MPS we need to normalize ?

Question

Hey all,
If I want to constuct a wave function that has a superposition of MPS, is it posible ? do I need to normalize it ?
For example:
psi= 1/sqrt(2) * MPS(s,"Up") + 1/sqrt(2) * MPS(s,"Dn")
hope for a reply soon =)

Answer 1

Hi, yes you can add two MPS together as you have written. Here is some more technical documentation on addition of MPS in ITensor: https://itensor.github.io/ITensors.jl/stable/MPSandMPO.html#Base.:+-Tuple{MPS,%20MPS}

Regarding the question of normalization, it is really your choice. If you wish the result to be normalized, you will need to normalize it. You can do this by putting factors in the sum as you have done, or normalizing the result afterward. If you do not want the resulting MPS to be normalized, then you can leave the factors out of the sum.

Best regards,
Miles