Physlib

Physlib.QuantumMechanics.FiniteTarget.HilbertSpace

The Hilbert space of a finite target quantum mechanical system

19 declarations

definition

nn-dimensional complex Hilbert space Cn\mathbb{C}^n

For a given natural number nn, the definition `FiniteHilbertSpace n` represents the nn-dimensional complex Hilbert space, mathematically equivalent to Cn\mathbb{C}^n, constructed as the Euclidean space over the complex numbers C\mathbb{C} with coordinates indexed by the finite set {0,1,,n1}\{0, 1, \dots, n-1\}.

instance

Additive commutative group structure of Cn\mathbb{C}^n

For any natural number nn, the nn-dimensional complex Hilbert space Cn\mathbb{C}^n (represented by `FiniteHilbertSpace n`) is equipped with the structure of an additive commutative group.

instance

Complex vector space structure of Cn\mathbb{C}^n

For any natural number nn, the nn-dimensional complex Hilbert space Cn\mathbb{C}^n (represented by `FiniteHilbertSpace n`) is equipped with the structure of a vector space over the field of complex numbers C\mathbb{C}.

instance

Normed additive commutative group structure of Cn\mathbb{C}^n

For any natural number nn, the nn-dimensional complex Hilbert space Cn\mathbb{C}^n (represented by `FiniteHilbertSpace n`) is equipped with the structure of a normed additive commutative group.

instance

Inner product space structure of Cn\mathbb{C}^n over C\mathbb{C}

For any natural number nn, the nn-dimensional complex Hilbert space Cn\mathbb{C}^n (represented by `FiniteHilbertSpace n`) is equipped with the structure of an inner product space over the field of complex numbers C\mathbb{C}.

instance

Cn\mathbb{C}^n is a complete space

For any natural number nn, the nn-dimensional complex Hilbert space Cn\mathbb{C}^n is a complete space.

theorem

(ψ+ϕ).val=ψ.val+ϕ.val(\psi + \phi).val = \psi.val + \phi.val

In the dd-dimensional complex Hilbert space Cd\mathbb{C}^d (modeled by `FiniteHilbertSpace d`), for any two vectors ψ\psi and ϕ\phi, the underlying coordinate representation of their sum ψ+ϕ\psi + \phi is equal to the sum of their individual coordinate representations: (ψ+ϕ).val=ψ.val+ϕ.val(\psi + \phi).val = \psi.val + \phi.val.

theorem

(cψ).val=cψ.val(c \cdot \psi).val = c \cdot \psi.val

In the dd-dimensional complex Hilbert space Cd\mathbb{C}^d (modeled by `FiniteHilbertSpace d`), for any complex number cc and any vector ψ\psi, the underlying coordinate representation of the scalar multiplication cψc \cdot \psi is equal to the scalar multiplication of cc and the coordinate representation of ψ\psi: (cψ).val=cψ.val(c \cdot \psi).val = c \cdot \psi.val.

theorem

The value of the zero vector in the finite Hilbert space is 00

In the dd-dimensional complex Hilbert space Cd\mathbb{C}^d, the value (coordinate representation) of the zero vector is equal to the zero vector 00.

definition

C\mathbb{C}-linear equivalence `FiniteHilbertSpace d` Cd\cong \mathbb{C}^d

For a natural number dd, this definition provides the C\mathbb{C}-linear equivalence (isomorphism of complex vector spaces) between the finite-dimensional Hilbert space `FiniteHilbertSpace d` and the standard complex Euclidean space Cd\mathbb{C}^d.

instance

Normed additive commutative group structure on Cd\mathbb{C}^d

For a natural number dd, the dd-dimensional complex Hilbert space Cd\mathbb{C}^d (represented by `FiniteHilbertSpace d`) is equipped with the structure of a normed additive commutative group. This means it possesses a commutative addition, a zero vector, additive inverses, and a norm \|\cdot\| that satisfies the triangle inequality.

theorem

ψ=ψ.val\|\psi\| = \|\psi.\text{val}\| for ψCd\psi \in \mathbb{C}^d

For any vector ψ\psi in the dd-dimensional complex Hilbert space Cd\mathbb{C}^d (represented by `FiniteHilbertSpace d`), the norm of ψ\psi, denoted as ψ\|\psi\|, is equal to the norm of its underlying value ψ.val\psi.\text{val}.

instance

Inner product space structure on Cd\mathbb{C}^d

For a natural number dd, the dd-dimensional complex Hilbert space (represented by `FiniteHilbertSpace d`, which is equivalent to Cd\mathbb{C}^d) is equipped with the structure of an inner product space over the complex numbers C\mathbb{C}. This defines a complex-valued inner product ,\langle \cdot, \cdot \rangle that is conjugate-linear in the first argument, linear in the second argument, and positive definite.

theorem

ψ,φ=ψ.val,φ.val\langle \psi, \varphi \rangle = \langle \psi.\text{val}, \varphi.\text{val} \rangle for vectors in Cd\mathbb{C}^d

In the dd-dimensional complex Hilbert space Cd\mathbb{C}^d (represented by `FiniteHilbertSpace d`), the inner product ψ,φ\langle \psi, \varphi \rangle of two vectors ψ\psi and φ\varphi is equal to the inner product of their underlying values ψ.val\psi.\text{val} and φ.val\varphi.\text{val}.

instance

The dd-dimensional complex Hilbert space is finite-dimensional over C\mathbb{C}

For any natural number dd, the dd-dimensional complex Hilbert space (represented as `FiniteHilbertSpace d`, which is equivalent to Cd\mathbb{C}^d) is a finite-dimensional vector space over the complex numbers C\mathbb{C}.

instance

The dd-dimensional complex Hilbert space Cd\mathbb{C}^d is complete

For any natural number dd, the dd-dimensional complex Hilbert space Cd\mathbb{C}^d is a complete space, meaning that every Cauchy sequence in the space converges to an element within it.

definition

Linear isometric equivalence FiniteHilbertSpace dCd\text{FiniteHilbertSpace } d \cong \mathbb{C}^d

For a natural number dd, the dd-dimensional complex Hilbert space (represented by `FiniteHilbertSpace d`) is linearly isometrically equivalent to the standard complex Euclidean space Cd\mathbb{C}^d. This equivalence is a bijective C\mathbb{C}-linear map that preserves the inner product and the norm.

definition

Standard orthonormal basis of Cd\mathbb{C}^d

For a finite index set dd, `basisFun` defines the standard orthonormal basis {ei}id\{e_i\}_{i \in d} for the dd-dimensional complex Hilbert space Cd\mathbb{C}^d (represented by `FiniteHilbertSpace d`). This basis is indexed by the elements of dd, where each basis vector eie_i corresponds to the unit vector in the ii-th coordinate, satisfying the orthonormality condition ei,ej=δij\langle e_i, e_j \rangle = \delta_{ij}.

theorem

The ii-th basis vector of the standard basis for Cd\mathbb{C}^d is the unit vector at ii

Let dd be a finite index set. For any element idi \in d, the ii-th basis vector of the standard orthonormal basis for the dd-dimensional complex Hilbert space Cd\mathbb{C}^d is equal to the vector with 11 at index ii and 00 elsewhere (the standard unit vector).