Physlib

PhyslibAlpha.AlgebraicFramework.HilbertSpace.State.Vector

Vector states

Vector states on spaces of continuous linear endomorphisms.

2 declarations

definition

Positive linear functional induced by ψ\psi (i.e., x↦⟨ψ,xψ⟩x \mapsto \langle \psi, x \psi \rangle)

Given a vector ψ\psi in an inner product space HH over a field k\mathbb{k}, this definition constructs the positive linear functional on the algebra of continuous linear operators B(H)\mathcal{B}(H) (denoted H→L[k]HH \to L[k] H). The functional maps each operator xx to the scalar value ⟨ψ,xψ⟩k\langle \psi, x \psi \rangle_{\mathbb{k}}, which corresponds to the expectation value of xx in the state ψ\psi.

definition

Vector state x↦⟨ψ,xψ⟩x \mapsto \langle \psi, x \psi \rangle associated with a unit vector ψ\psi

For a unit vector ψ\psi in an inner product space HH over a field k\mathbb{k} (where ∥ψ∥=1\|\psi\| = 1), this definition constructs the unital positive linear map (state) on the algebra of continuous linear operators B(H)\mathcal{B}(H). The map sends each operator x∈B(H)x \in \mathcal{B}(H) to the scalar value ⟨ψ,xψ⟩\langle \psi, x \psi \rangle.