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Physlib.QuantumMechanics.OperatorAlgebra.Observables.Jordan

Jordan structure on observables

The observables of a complex C⋆-algebra carry the symmetrized product

a ⊙ b = 1/2 (ab + ba),

equivalently the real part of their algebra product.

This product is commutative and satisfies the Jordan identity. The type `JordanObservable A` equips the real vector space of observables with this product as its multiplication, giving a commutative Jordan algebra.

Jordan observables

`JordanObservable A` is the same underlying real vector space equipped with the symmetrized product as multiplication.

14 declarations

definition

Jordan product aba \odot b of observables

For two observables aa and bb in a complex CC^*-algebra AA, their Jordan product aba \odot b is defined as the symmetrized product 12(ab+ba)\frac{1}{2}(ab + ba), which corresponds to the real part of their algebraic product in AA.

definition

Jordan product notation aba \odot b for observables

The notation aba \odot b represents the Jordan product of two observables aa and bb, defined by the symmetrized product 12(ab+ba)\frac{1}{2}(ab + ba).

theorem

ab=12(ab+ba)a \odot b = \frac{1}{2}(ab + ba)

Let AA be a complex CC^*-algebra. For any two observables a,bAa, b \in A (defined as self-adjoint elements where a=aa^* = a and b=bb^* = b), their Jordan product aba \odot b is given by the symmetrized product ab=12(ab+ba)a \odot b = \frac{1}{2}(ab + ba) where the multiplication and addition are those of the underlying algebra AA.

theorem

Commutativity of the Jordan product ab=baa \odot b = b \odot a

For any two observables aa and bb in a complex CC^*-algebra AA, the Jordan product aba \odot b is commutative, satisfying ab=baa \odot b = b \odot a. Here, the Jordan product is the symmetrized product defined by ab=12(ab+ba)a \odot b = \frac{1}{2}(ab + ba).

theorem

aa=a2a \odot a = a^2 for observables

Let AA be a complex CC^*-algebra. For any observable aAa \in A (a self-adjoint element), the Jordan product of aa with itself is equal to its square in the algebra, i.e., aa=a2a \odot a = a^2.

theorem

(a+b)c=ac+bc(a + b) \odot c = a \odot c + b \odot c

Let AA be a complex CC^*-algebra. For any observables a,b,cAa, b, c \in A (self-adjoint elements), the Jordan product xy=12(xy+yx)x \odot y = \frac{1}{2}(xy + yx) satisfies the distributive law (a+b)c=ac+bc(a + b) \odot c = a \odot c + b \odot c.

theorem

a(b+c)=ab+aca \odot (b + c) = a \odot b + a \odot c

Let AA be a complex CC^*-algebra. For any observables (self-adjoint elements) a,b,ca, b, c in AA, the Jordan product \odot distributes over addition such that a(b+c)=ab+aca \odot (b + c) = a \odot b + a \odot c.

theorem

a(tb)=t(ab)a \odot (t \cdot b) = t \cdot (a \odot b)

Let AA be a complex CC^*-algebra and let a,ba, b be observables in AA (self-adjoint elements such that a=aa = a^* and b=bb = b^*). For any real scalar tRt \in \mathbb{R}, the Jordan product ab=12(ab+ba)a \odot b = \frac{1}{2}(ab + ba) satisfies the scalar homogeneity property: a(tb)=t(ab)a \odot (t \cdot b) = t \cdot (a \odot b)

theorem

Jordan Identity for Observables: (ab)(aa)=a(b(aa))(a \odot b) \odot (a \odot a) = a \odot (b \odot (a \odot a))

Let AA be a complex CC^*-algebra. For any observables (self-adjoint elements) a,bAa, b \in A, the Jordan product defined by ab=12(ab+ba)a \odot b = \frac{1}{2}(ab + ba) satisfies the Jordan identity: (ab)(aa)=a(b(aa)) (a \odot b) \odot (a \odot a) = a \odot (b \odot (a \odot a))

definition

Jordan observables of an operator algebra AA

Let AA be an operator algebra. The type `JordanObservable A` is defined as the space of observables (self-adjoint elements aAa \in A such that a=aa = a^*) equipped with the symmetrized Jordan product ab=12(ab+ba)a \odot b = \frac{1}{2}(ab + ba). It is a type synonym for `Observable A` used to provide the structure of a commutative Jordan algebra.

instance

JordanObservable A\text{JordanObservable } A is an additive commutative group

For an operator algebra AA, the space of Jordan observables JordanObservable(A)\text{JordanObservable}(A) is an additive commutative group. This structure is inherited from the additive group structure of the space of observables Observable(A)\text{Observable}(A).

instance

R\mathbb{R}-module structure on JordanObservable A\text{JordanObservable } A

For an operator algebra AA, the space of Jordan observables JordanObservable(A)\text{JordanObservable}(A) is a module over the real numbers R\mathbb{R}. This vector space structure is inherited from the space of self-adjoint observables Observable(A)\text{Observable}(A).

instance

JordanObservable A\text{JordanObservable } A is a non-unital non-associative commutative ring

For an operator algebra AA, the space of Jordan observables JordanObservable A\text{JordanObservable } A is equipped with the structure of a non-unital non-associative commutative ring. The multiplication in this ring is the Jordan product, defined for any two observables a,ba, b as ab=12(ab+ba)a \odot b = \frac{1}{2}(ab + ba). This product is commutative (ab=baa \odot b = b \odot a) and satisfies the distributive laws a(b+c)=ab+aca \odot (b + c) = a \odot b + a \odot c and (a+b)c=ac+bc(a + b) \odot c = a \odot c + b \odot c.

instance

JordanObservable A\text{JordanObservable } A is a Commutative Jordan Algebra

Let AA be an operator algebra. The space of Jordan observables JordanObservable A\text{JordanObservable } A, consisting of the self-adjoint elements of AA equipped with the symmetrized product ab=12(ab+ba)a \odot b = \frac{1}{2}(ab + ba), is a commutative Jordan algebra. This means the product is commutative and satisfies the Jordan identity (a2b)a=a2(ba)(a^2 \odot b) \odot a = a^2 \odot (b \odot a) for all a,bJordanObservable Aa, b \in \text{JordanObservable } A.