ITensor / ITensor/ITensorMPS.jl

[ITensors] [ENHANCEMENT] AD `rrules`

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enhancement
Dominant language
Julia
Stars
85
Forks
27
Avg merge
22m
Merged PRs (30d)
1

Description

List of rrule currently missing:

Possibly easy to be implemented:

  • MPS(::Vector{ITensor}, ...)
  • MPO(::Vector{ITensor}, ...)
  • convert(MPS, ::MPO)
  • *(::Number, ::MPS) / *(::Number, ::MPO)
  • outer(::MPS, ::MPS)
  • apply(U, ...) where U is a single tensor (instead of a vector)

Requires more thought:

  • apply(U, ::MPS) with "noisy" (rank-3) U tensor
  • exp(::OpSum; kwargs...), including the entire Op system.
  • entanglemententropy(::MPS) for disentangling unitary optimization.

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the unchecked API entry points listed in the issue, including MPO construction, MPS/MPO conversion and scalar multiplication, then review the existing MPS constructor marked complete for precedent. The work is done when the selected missing rrules are implemented and the behavior of each listed operation is verified, with the items requiring more thought resolved separately.

Written by the indexing model from the issue text.

Assessment

Tech stack
julia
Domain
hpc
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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