leanprover-community / leanprover-community/physlib

Thoughts on the definition of Hilbert Space and Bra-Ket

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Description

Version bump
  1. Why PhysLean decides to define finite Hilbert Space and infinite Hilbert Space separately?
  2. We try to define Ket as a linear map (eg. noncomputable def Ket: ℂ →ₗ[ℂ] H := (innerSL ℂ 1).toLinearMap.smulRight ψ), so that we can use the uniform notation tensor product of map (eg. f "⊗ₘ" g => TensorProduct.map f g) for calculation like this: ((⟨ψ| ⊗ₘ ⟨φ|) ∘ₛₗ (|ψ⟩ ⊗ₘ |φ⟩)). And also, Ket definition can both used for infinite Hilbert Space and finite Hilbert Space. How do you think of this definition? What are pros and cons of doing this?

Contributor guide

Open the contributing guide

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 by reviewing the existing finite and infinite Hilbert Space definitions and the proposed Ket linear-map definition described in the issue. Compare the notation and tensor-product composition goals, then establish and document the project direction for supporting both cases.

Written by the indexing model from the issue text.

Assessment

Domain
tooling
Issue type
Refactor
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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