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Trace-class bounded-observable response

1 · Prerequisites

2 · Summary

This page separates finite-matrix response, trace-class normal-state response, and response on the quasi-local algebra of finite-range quantum spin systems. It proves the bounded-observable Kubo formula with an explicit finite-time remainder, records the precise graph-domain conditions needed for a strong Schrödinger solution, and derives the finite spectral fluctuation–dissipation relation with its zero-frequency qualification.

The infinite-Hilbert-space results use trace-class densities and bounded observables only; they do not use an unbounded trace product or assume finite energy or entropy moments. The infinite-spin result instead uses an invariant algebraic state on the actual finite-range automorphism group, not a global trace Hamiltonian. Neither a spatial finite-range bound nor isolated pure-point dynamics supplies temporal decay or a dc transport coefficient. The two physical postulates are adopted model assumptions, and the prepared-control physics theorem is a conditional prediction rather than an empirical observation.

3 · Logical flowchart

4 · Definitions, postulates, theorems and proofs

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Banach-space Volterra and Dyson series with a norm remainder

Statement

Let X be a complex Banach space, let T>0, and let B(X) be the bounded complex-linear operators on X with operator norm ∥L∥:=sup⁡{∥Lx∥:x∈X, ∥x∥≤1}. Let K:[0,T]→B(X) be strongly continuous, meaning t↦K(t)x is norm-continuous for every fixed x∈X. Suppose a continuous function a:[0,T]→[0,∞) satisfies ∥K(t)∥≤a(t). Set cT=∫0Ta(s) ds, where the scalar integral is the Riemann integral. Define Δ0(t)=x0 and recursively Δn(t)=∫0tK(s)Δn−1(s) ds for n≥1, using the norm-Riemann integral in X.

For each ϵ∈C, the series xϵ(t)=∑n=0∞ϵnΔn(t) converges uniformly on [0,T]. It is the unique continuously differentiable solution of xϵ′(t)=ϵK(t)xϵ(t) and xϵ(0)=x0, and

∥xϵ(t)−x0−ϵ∫0tK(s)x0 ds∥≤∥x0∥(∣ϵ∣cT)2e∣ϵ∣cT2.

If X is a unital complex C∗-algebra and K(t)x=b(t)x for a norm-continuous curve b:[0,T]→X of skew-adjoint elements, then for real ϵ the solution with x0=1 is unitary. If X=H is a complex Hilbert space and each K(t) is a bounded skew-adjoint operator, then for real ϵ the solution operators Wϵ(t):x0↦xϵ(t) are unitary even when K(t) is only strongly continuous.

Facts & Assumptions

Given: A complex Banach space X, a strongly continuous bounded-operator family K(t), a continuous nonnegative majorant a(t), and x0∈X.

[F1]

Riemann integration of continuous curves in a complete normed space, with the fundamental theorem of calculus and coefficient functionals: a continuous curve in a complete normed real vector space has a norm-Riemann integral; the integral is linear, additive, commutes with bounded linear maps, obeys the norm bound obtained from Riemann sums, and its indefinite integral has derivative equal to the integrand. A complex Banach space is used as its underlying real Banach space.

[F2]

C star algebra: a complex C∗-algebra is a complete normed ∗-algebra with submultiplicative norm and ∥z∗z∥=∥z∥2; the unital case has an identity element.

Proof

Given: The Banach space, coefficient family, majorant and initial value in the Statement.

1.1givenF1construct

If x:[0,T]→X is continuous, then s↦K(s)x(s) is continuous: for s→t, its difference from K(t)x(t) is bounded by sup⁡r∥K(r)∥∥x(s)−x(t)∥+∥K(s)x(t)−K(t)x(t)∥, and both terms tend to zero. By [F1], the norm-Riemann integral defining Δn+1 therefore exists whenever Δn is continuous. Moreover, for a continuous f:[0,t]→X, the triangle inequality on each tagged Riemann sum and convergence of the scalar Riemann sums give ∥∫0tf(s) ds∥≤∫0t∥f(s)∥ ds.

2.1givenstep 1.1F1algebra

Put Θ(t)=∫0ta(s) ds. By [F1], Θ is continuously differentiable and Θ′=a. Inductively the curves Δn are continuous and satisfy ∥Δn(t)∥≤∥x0∥Θ(t)n/n!: it is equality as a bound for n=0, and if it holds at n, then ∥Δn+1(t)∥≤∫0ta(s)∥Δn(s)∥ ds≤∥x0∥∫0ta(s)Θ(s)n/n! ds=∥x0∥Θ(t)n+1/(n+1)!, where the last equality follows by differentiating Θn+1/(n+1)!.

3.1step 1.1step 2.1F1algebra

Since Θ(t)≤cT, the bound in step 2.1 gives uniform absolute convergence of ∑nϵnΔn(t). Uniform convergence, the integral bound in step 1.1, and the recursion show xϵ(t)=x0+ϵ∫0tK(s)xϵ(s) ds; [F1] then gives the differential equation and initial value. If two solutions differ by z, repeated substitution in z(t)=ϵ∫0tK(s)z(s) ds gives ∥z(t)∥≤sup⁡[0,T]∥z∥(∣ϵ∣cT)n/n! for every n, whose right side tends to zero; hence the solution is unique.

4.1step 2.1step 3.1algebra

With y=∣ϵ∣cT, the tail after its linear term is at most ∥x0∥∑n≥2yn/n!≤∥x0∥y2ey/2, because n!≥2(n−2)! for every n≥2. This is the stated remainder.

4.2givenF2step 3.1algebra

In the C∗-algebra case, write W=xϵ and assume b(t)∗=−b(t) and ϵ∈R. The product rule and W′=ϵbW give (W∗W)′=ϵW∗(b∗+b)W=0, so W∗W=1. Also Z=WW∗ satisfies Z′=ϵ(bZ−Zb) and Z(0)=1. The uniqueness argument of step 3.1, applied to the bounded operator family Z↦ϵ(b(t)Z−Zb(t)), shows that the constant curve Z=1 is its only solution. Hence WW∗=1 as well, so W is unitary in the unital C∗-algebra.

5.1givenstep 2.1step 3.1algebra∎

In the Hilbert-space case, the series is linear in x0 and step 2.1 gives ∥Wϵ(t)x0∥≤e∣ϵ∣cT∥x0∥, so it defines a bounded operator. Differentiating inner products of two solutions gives ddt⟨Wϵ(t)x,Wϵ(t)y⟩=ϵ⟨K(t)Wϵ(t)x,Wϵ(t)y⟩+ϵ⟨Wϵ(t)x,K(t)Wϵ(t)y⟩=0, hence Wϵ(t) is an isometry. For a fixed terminal time t, solve z′(s)=−ϵK(t−s)z(s) on [0,t] with arbitrary z(0)=y using the first part; then x(s)=z(t−s) solves the forward equation and Wϵ(t)x(0)=y. Thus Wϵ(t) is onto and therefore unitary.

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Finite matrix trace-norm ideal inequalities

Statement

Let H be a complex Hilbert space of finite dimension d≥1. For a matrix X define ∣X∣=(X∗X)1/2 by finite Hermitian functional calculus and define its trace norm by ∥X∥1=Tr⁡∣X∣. This is a complete norm on the finite-dimensional matrix space. Write ∥Y∥:=sup⁡{∥Yv∥:∥v∥≤1} for the operator norm induced by the Hilbert-space norm. For all matrices X,Y,

∥YX∥1≤∥Y∥∥X∥1,∥XY∥1≤∥Y∥∥X∥1,∣Tr⁡X∣≤∥X∥1.

For unitary U, ∥UXU∗∥1=∥X∥1.

Facts & Assumptions

Given: A complex inner-product space H of finite dimension d≥1 and matrices X,Y.

[F1]

Finite matrix spectral and state calculus: every positive Hermitian matrix has a basis-independent orthonormal spectral decomposition and positive square root; the finite trace is basis independent.

Proof

technique · direct

Given: The finite-dimensional Hilbert space and matrices above.

1.1givenF1construct

Diagonalize X∗X by [F1], with nonnegative eigenvalues sj2 and orthonormal eigenvectors vj. For each sj>0 put uj=Xvj/sj; then ⟨ui,uj⟩=δij because ⟨Xvi,Xvj⟩=⟨vi,X∗Xvj⟩. Extending both finite orthonormal families to bases gives the singular-value expansion X=∑sj>0sjRuj,vj, where Ru,vx=⟨x,v⟩u. The only nonzero singular value of Ru,v is ∥u∥∥v∥, so ∥Ru,v∥1=∥u∥∥v∥ and ∥X∥1=∑sj>0sj.

2.1step 1.1F1algebra

The rank-one trace formula is Tr⁡(Ru,v)=⟨u,v⟩, so the expansion in step 1.1 gives ∥X∥1=sup⁡U unitary∣Tr⁡(UX)∣. For the upper bound, if uj,vj are unit vectors, then ∥Uuj−⟨Uuj,vj⟩vj∥2=1−∣⟨Uuj,vj⟩∣2≥0, so ∣⟨Uuj,vj⟩∣≤1. Equality is attained by a unitary mapping each uj to vj, extended from these finite orthonormal families to bases. The supremum formula implies the triangle inequality ∥X+Y∥1≤∥X∥1+∥Y∥1 and homogeneity; positivity and definiteness follow from the singular values.

3.1step 1.1step 2.1algebra

Applying step 1.1 to YX=∑jsjRYuj,vj and using the triangle inequality of step 2.1 gives ∥YX∥1≤∑jsj∥Yuj∥∥vj∥≤∥Y∥∑jsj=∥Y∥∥X∥1. Similarly XY=∑jsjRuj,Y∗vj gives ∥XY∥1≤∥Y∥∥X∥1. The rank-one trace formula and step 1.1 also give ∣Tr⁡X∣≤∑jsj∣⟨uj,vj⟩∣≤∥X∥1.

4.1step 3.1algebra∎

Define the Frobenius norm by ∥X∥F=(∑i,j∣Xij∣2)1/2 in an orthonormal basis. The finite singular-value expansion gives ∥X∥F=(∑jsj2)1/2. Since sj≥0, (∑jsj2)1/2≤∑jsj; also d∑jsj2−(∑jsj)2=∑i<j(si−sj)2≥0. Thus ∥X∥F≤∥X∥1≤d ∥X∥F. A trace-norm Cauchy sequence is therefore Cauchy in each matrix coordinate and converges to a matrix; the second inequality gives convergence in trace norm. This proves completeness. For unitary U, step 3.1 gives ∥UX∥1≤∥X∥1; applying it to U∗ and UX gives the reverse inequality. The same argument on the right proves ∥UXU∗∥1=∥X∥1.

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Lorentzian kernels converge to delta and principal-value distributions

Statement

Let ψ:R→C be continuously differentiable with compact support. For η>0, define Pη(x)=η/(x2+η2) and Qη(x)=x/(x2+η2). Define PV⁡ ⁣∫Rψ(x)x dx:=lim⁡δ↓0∫∣x∣>δψ(x)x dx when this symmetric limit exists. Then lim⁡η↓0∫RPη(x)ψ(x) dx=πψ(0),lim⁡η↓0∫RQη(x)ψ(x) dx=PV⁡ ⁣∫Rψ(x)x dx. Thus Pη converges distributionally to πδ0, and Qη converges distributionally to the Cauchy principal-value distribution PV⁡(1/x), with the stated test-function convention.

Facts & Assumptions

Given: A compactly supported C1 complex test function ψ and the Lebesgue measure on R.

[F1]

Dominated convergence: almost-everywhere convergence under one integrable measurable majorant implies convergence of the integrals.

Proof

Given: The test function and kernels in the Statement.

1.1givenF1algebra

With x=ηy, the first integral is ∫Rψ(ηy)/(1+y2) dy. Its integrand converges pointwise to ψ(0)/(1+y2) and is bounded in modulus by ∥ψ∥∞/(1+y2), an integrable function. By [F1] the limit is ψ(0)∫R(1+y2)−1 dy=πψ(0); the last integral is arctan⁡(y)∣−∞∞=π.

1.2givenF1algebra

Let L=sup⁡x∣ψ′(x)∣<∞ and set q(x)=ψ(x)−ψ(0)1[−1,1](x). The integral of Qη(x)ψ(0)1[−1,1](x) is zero because its integrand is odd on a symmetric interval. For 0<∣x∣≤1, ∣Qη(x)q(x)∣≤Lx2/(x2+η2)≤L by the mean-value inequality; for ∣x∣>1, ∣Qη(x)q(x)∣≤∣ψ(x)∣. This gives an integrable majorant independent of η, and for x≠0 the integrand tends to q(x)/x. Applying [F1] yields ∫Rq(x)/x dx.

2.1step 1.1step 1.2algebra∎

For 0<δ<1, the constant part ψ(0)/x integrates to zero on {δ<∣x∣≤1} by oddness. Therefore ∫q(x)/x dx=lim⁡δ↓0∫∣x∣>δψ(x)/x dx, proving existence of the symmetric principal value and the second limit. The two distributional conclusions are precisely the limits already established in steps 1.1 and 1.2.

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Stationary-state covariance identity for time-integrated observables

Statement

Let A be a unital complex C∗-algebra, and let (αt)t∈R be a group of ∗-automorphisms of A, so α0=id⁡A and αs+t=αs∘αt. Assume point-norm continuity: for each X∈A, the orbit map t↦αt(X) is norm-continuous. Let ϕ:A→C be a bounded linear functional with ϕ(I)=1, ϕ(X∗X)≥0 for every X∈A, and ϕ∘αt=ϕ for every t. For m≥1, take self-adjoint V1,…,Vm∈A with ϕ(Va)=0. For T>0, regard A as its underlying real Banach space with the same norm for these time integrals, and define the norm-Riemann integrals Xa,T=∫0Tαt(Va) dt, and for s≥0 define Gab(s)=12(Re⁡ϕ(Vaαs(Vb))+Re⁡ϕ(Vbαs(Va))). Then each Xa,T is self-adjoint and 12TRe⁡ϕ(Xa,TXb,T)=∫0T(1−sT)Gab(s) ds. The real symmetric matrix with entries on the left is positive semidefinite.

Facts & Assumptions

Given: The unital C∗-algebra, strongly continuous automorphism group, invariant state, self-adjoint centered observables, and T>0 in the Statement.

[F1]

C star algebra: A is complete, multiplication is bounded, and the involution is continuous.

[F2]

Riemann integration of continuous curves in a complete normed space, with the fundamental theorem of calculus and coefficient functionals: continuous curves in a complete normed real vector space have norm-Riemann integrals, with linearity, additive subdivision, bounded-functional interchange, and the norm estimate from Riemann sums; for these integrals, the complex algebra A is viewed as its underlying real Banach space.

Proof

technique · direct double integration over the time square, followed by stationarity and positivity

Given: [F1]–[F2], the bounded normalized positive functional, and the invariant group in the Statement.

1.1givenF1F2algebra

The functional is Hermitian: if H=H∗ then ϕ((I+rH)∗(I+rH))=1+2rϕ(H)+r2ϕ(H2) is real for every real r, so ϕ(H)∈R; decomposing X=(X+X∗)/2+i(X−X∗)/(2i) gives ϕ(X∗)=ϕ(X)‾. For each a, t↦αt(Va) is norm-continuous, so [F2] defines Xa,T. Riemann sums of self-adjoint elements are self-adjoint, and continuity of the involution in [F1] passes this property to the limit. The product map (s,t)↦αs(Va)αt(Vb) is norm-continuous on [0,T]2 by continuity of multiplication; approximating each integral by Riemann sums and multiplying the sums shows Xa,TXb,T equals the iterated integral of this product.

2.1givenF1F2step 1.1algebra

Invariance of ϕ and the group law give ϕ(αs(Va)αt(Vb))=ϕ(Vaαt−s(Vb)) for every s,t∈[0,T]. The scalar integrand is continuous; splitting the square into the triangles t≥s and s≥t, and integrating the slices with fixed u=∣t−s∣, whose lengths are T−u, yields ϕ(Xa,TXb,T)=∫0T(T−u)ϕ(Vaαu(Vb)) du+∫0T(T−u)ϕ(Vaα−u(Vb)) du. The diagonal has zero area and does not affect the Riemann integral. The slice formula follows from the one-variable substitution u=t−s on each triangle and the additivity of the Riemann integral.

3.1step 1.1step 2.1algebra

For u≥0, invariance gives ϕ(Vaα−u(Vb))=ϕ(αu(Va)Vb)=ϕ(Vbαu(Va))‾, where the last equality uses self-adjointness and step 1.1. Taking real parts in step 2.1 therefore gives the stated identity after dividing by 2T.

4.1givenstep 1.1algebra∎

For any real vector c=(c1,…,cm), Xc,T=∑acaXa,T is self-adjoint and ∑a,bcacbRe⁡ϕ(Xa,TXb,T)=ϕ(Xc,T2)=ϕ(Xc,T∗Xc,T)≥0 by positivity. Hermiticity from step 1.1 gives symmetry of the real matrix, so it is positive semidefinite.

TheoremStatement: Literature-sourcedProof: AI-adaptedOpen item page →

Trace-class bounded-observable response

Statement

Assume the Axiom of Choice. Let H≠{0} be a separable complex Hilbert space, let H=H∗ be a densely defined operator with domain D(H), and let ℏ>0. Put U0(t)=e−itH/ℏ. Let ρ be a density operator, meaning a positive trace-class operator with Tr⁡ρ=1 as in Trace-class normal density states, and assume ρU0(t)=U0(t)ρ for every t∈R. Let A,B∈B(H) be bounded self-adjoint operators, let T>0 be a finite time in s, let h:[0,T]→R be continuous, and let ϵ∈R be dimensionless. Interpret H in J, ℏ in J s, and h(t)B in J; if A,B carry units [A],[B], then RAB has units [A][B]/(J s).

Define Bs=U0(s)∗BU0(s), αt(A)=U0(t)∗AU0(t), and

RAB(u)=iℏTr⁡ ⁣(ρ[αu(A),B]),CT=2ℏ∫0T∣h(s)∣ ∥B∥ ds.

The trace-class interaction-picture solution of ρI′(t)=iϵh(t)ℏ[Bt,ρI(t)], ρI(0)=ρ, satisfies

Tr⁡(ρI(t)αt(A))=Tr⁡(ραt(A))+ϵ∫0th(s)RAB(t−s) ds+rϵ(t),

where ∣rϵ(t)∣≤∥A∥(∣ϵ∣CT)2e∣ϵ∣CT/2 for 0≤t≤T. Thus the bounded-observable first variation is exact, with an explicit finite-time remainder. No energy or entropy moment of ρ is assumed, and no trace of an unbounded product such as ρHA is used.

Facts & Assumptions

Given: Choice, the Hilbert space, self-adjoint H, ℏ>0, trace-class density ρ, bounded self-adjoint A,B, continuous real control h, and finite T.

[A1]

The Axiom of Choice: the full Axiom of Choice is assumed for the unbounded spectral theorem used to define U0(t).

[F1]

Trace-class normal density states: a density operator is positive, trace class, and has trace one; its state pairing with a bounded operator is ωρ(A)=Tr⁡(ρA).

[F2]

A self-adjoint operator generates a strongly continuous unitary group: under [A1], U0(t)=e−itH/ℏ is a strongly continuous unitary group, preserves D(H), and differentiates there; the exact scale change from eisH is s=−t/ℏ.

[F3]

Trace class is a two sided Banach operator ideal: trace-class operators are complete in trace norm, bounded left/right multiplication is trace-class, and ∥AXB∥1≤∥A∥∥X∥1∥B∥.

[F4]

Cyclicity of the trace: for trace-class X and bounded Y, Tr⁡(YX)=Tr⁡(XY).

[F5]

Trace is absolutely convergent and basis independent: the trace is linear and basis independent, and ∣Tr⁡X∣≤∥X∥1.

[F6]

Banach-space Volterra and Dyson series with a norm remainder: a strongly continuous bounded coefficient on a Banach space has a unique norm-convergent Volterra series solution with the stated quadratic remainder; its Hilbert-space clause gives a unitary solution operator for a strongly continuous skew-adjoint coefficient.

[F7]

Nuclear series characterizes trace norm: each trace-class operator has a nuclear singular-value representation with summable singular values. Its finite-rank partial sums XN satisfy ∥X−XN∥1≤∑j>Nsj(X)→0: the tail is a nuclear representation, and the supplier's infimum formula bounds its trace norm by that tail sum.

[F8]

Trace of a positive operator is the sum of its eigenvalues: for a positive trace-class operator ρ, Tr⁡ρ=∥ρ∥1.

Proof

technique · direct

Given: [A1], [F1]–[F6], and the stationarity condition ρU0(t)=U0(t)ρ.

1.1givenA1F2F3F7algebra

For a rank-one operator Ru,vx=⟨x,v⟩u, one has ∥Ru,v∥1=∥u∥∥v∥, and ∥Ru,v−Ru′,v′∥1≤∥u−u′∥∥v∥+∥u′∥∥v−v′∥. Strong continuity in [F2] therefore makes t↦U0(t)Ru,vU0(t)∗ trace-norm continuous. Finite sums have the same property. By [F7], finite-rank SVD truncations XN of any trace-class X satisfy ∥X−XN∥1→0. The ideal estimate in [F3] and ∥U0(t)∥=∥U0(t)∗∥=1 bound the conjugated tails uniformly by ∥X−XN∥1, so t↦U0(t)XU0(t)∗ is trace-norm continuous.

1.2givenF2F3F7algebra

For finite-rank XN=∑j=1mRuj,vj, BtXN=∑jRBtuj,vj and XNBt=∑jRuj,Btvj because Bt=Bt∗. Strong continuity of Bt makes both curves trace-norm continuous. For general trace-class X, take the finite-rank approximants from [F7] and use ∥Bt(X−XN)∥1,∥(X−XN)Bt∥1≤∥B∥∥X−XN∥1 uniformly in t. Thus X↦ih(t)ℏ[Bt,X] is strongly continuous on the trace-class Banach space and has norm bound 2∣h(t)∣∥B∥/ℏ.

1.3givenF1F3F6F7F8algebra

Apply [F6] on the trace-class Banach space with Kt(X)=ih(t)ℏ[Bt,X] and x0=ρ. By [F1] and [F8], ρ is positive, has trace one, and satisfies ∥ρ∥1=1; its Volterra solution has the claimed trace-norm linear approximation and remainder bound with CT=2ℏ∫0T∣h(s)∣∥B∥ ds. The Hilbert clause of [F6], applied to Kt=ih(t)Bt/ℏ on H, gives a unitary solution operator W(t)=Wϵ(t) satisfying W′(t)u=ϵih(t)BtW(t)u/ℏ for every u∈H. For a rank-one Ru,v, W(t)Ru,vW(t)∗=RW(t)u,W(t)v is trace-norm differentiable and its derivative is ϵKt(W(t)Ru,vW(t)∗), by the vector equation and skew-adjointness. Finite sums give the same integral equation. Approximate ρ by finite-rank ρN in trace norm using [F7]. Unitary invariance of trace norm follows from the ideal estimate [F3] applied to W(t) and W(t)∗, both of norm one; hence W(t)ρNW(t)∗→W(t)ρW(t)∗ uniformly, while the right-hand integral errors are at most ∣ϵ∣CT∥ρ−ρN∥1. Thus W(t)ρW(t)∗ solves the trace-class Volterra equation, and uniqueness in [F6] identifies it with ρI(t).

2.1givenF2F4step 1.3algebra

The linear term in the expectation is iϵℏ∫0th(s)Tr⁡([Bs,ρ]αt(A)) ds. By [F4], the trace integrand equals Tr⁡(ρ[αt(A),Bs]). The group law and stationarity give [αt(A),Bs]=αs([αt−s(A),B]) and Tr⁡(ραs(C))=Tr⁡(ρC) for bounded C. Hence the integrand is Tr⁡(ρ[αt−s(A),B]), producing the stated convolution and response kernel.

3.1givenF3F4F5step 1.3step 2.1algebra∎

The trace-norm remainder in step 1.3 changes the expectation by at most ∥A∥∥ρI(t)−ρ−ϵ∫0tKs(ρ) ds∥1 by [F3, F5]. This gives the stated bound. Since A,B are self-adjoint and ρ is positive, the commutator trace is purely imaginary by cyclicity; hence RAB(u) is real. No moment of H occurs in any trace.

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Finite unitary dynamics and stationary Gibbs states

Statement

Let H be a complex Hilbert space of finite dimension d≥1, let H=H∗ be a Hamiltonian with energy unit J, and let ℏ>0 have unit J s. A finite density matrix is a positive semidefinite matrix ρ with Tr⁡ρ=1. For time t∈R measured in s, set U(t)=e−itH/ℏ and αt(A)=U(t)∗AU(t). Then U(t) is a unitary group, αt is a group of matrix ∗-automorphisms, and for every finite density matrix ρ and matrix A,

Tr⁡(U(t)ρU(t)∗A)=Tr⁡(ραt(A)).

The von Neumann entropy S(ρ)=−kBTr⁡(ρlog⁡ρ) is defined using log⁡ρ on the positive spectral support, with zero eigenvalues contributing 0 (the convention 0log⁡0:=0), and is finite and unchanged by U(t)ρU(t)∗. For β>0 with unit J−1, let Zβ=Tr⁡(e−βH) and σβ=Zβ−1e−βH. Then Zβ>0, σβ is stationary, and the finite Gibbs correlation has the KMS strip identity

FA,B(t+iβℏ)=Tr⁡(σβαt(B)A),FA,B(z)=Tr⁡(σβAαz(B)),

where αz(B)=eizH/ℏBe−izH/ℏ. The function FA,B is entire and bounded on 0≤Im⁡z≤βℏ. This finite-dimensional result asserts no approach to equilibrium.

Facts & Assumptions

Given: A finite-dimensional complex Hilbert space, H=H∗, ℏ>0, β>0, matrices A,B, and a positive semidefinite matrix ρ with trace one.

[F1]

Finite matrix spectral and state calculus: every Hermitian matrix has a real spectral decomposition; the finite trace is cyclic; positive matrices have basis-independent spectral functional calculus, including the logarithm on positive support.

[F2]

Finite unitary dynamics and Gibbs KMS identity: for finite-dimensional H=H∗ and β>0, σβ is stationary and FA,B is entire, bounded on the strip 0≤Im⁡z≤βℏ, with boundary value FA,B(t+iβℏ)=Tr⁡(σβαt(B)A). Its current draft proof is the inspected finite spectral calculation; no infinite-volume KMS claim is used.

Proof

Given: The finite-dimensional Hamiltonian, density matrix, and constants in the Statement.

1.1givenF1algebra

Diagonalize H using [F1], with eigenvalues Ej∈R. The eigenvalues of U(t) are e−itEj/ℏ, so U(t)∗U(t)=I and multiplication of the scalar phases gives U(t+s)=U(t)U(s). Conjugation therefore makes each αt a unital matrix ∗-automorphism and gives the group law.

2.1givenF1step 1.1algebra

By cyclicity in [F1], Tr⁡(UρU∗A)=Tr⁡(ρU∗AU). Unitary conjugation preserves the eigenvalues of ρ, so it preserves the finite entropy and Tr⁡ρ=1. Since e−βH is positive definite in finite dimension, its trace is positive; it commutes with U(t), so σβ is stationary.

3.1givenF1F2step 1.1algebra∎

In the eigenbasis of H, each entry of αz(B) is a constant multiple of eiz(Ej−Ek)/ℏ, hence is entire. The finite-dimensional trace makes FA,B entire. The KMS boundary identity and boundedness on the specified strip are exactly [F2] under the same hypotheses.

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Finite Cesaro dephasing with degenerate energy blocks

Statement

Under the finite-dimensional unitary dynamics of Finite unitary dynamics and stationary Gibbs states, let PE be the orthogonal spectral projection of H for its distinct energy E. For every density matrix ρ,

1T∫0TU(t)ρU(t)∗ dt⟶∑EPEρPE

in trace norm as T→∞. The diagonal energy blocks, including all blocks within degenerate eigenspaces, remain. This is Cesaro convergence of the averaged state; pointwise convergence of U(t)ρU(t)∗ is not asserted.

Facts & Assumptions

Given: A finite-dimensional H, a Hermitian H, ℏ>0, and a positive matrix ρ with trace one.

[F1]

Finite unitary dynamics and stationary Gibbs states: U(t)=e−itH/ℏ is unitary and has the finite-dimensional spectral dynamics of the Statement.

[F2]

Finite matrix trace-norm ideal inequalities: the finite trace norm is a norm on the matrix space, so convergence of finite sums in that norm is well defined.

Proof

Given: The finite-dimensional unitary evolution and density matrix above.

1.1givenF1algebra

Write H=∑EEPE by finite Hermitian spectral calculus. Then U(t)ρU(t)∗=∑E,Fe−i(E−F)t/ℏPEρPF. There are finitely many ordered pairs (E,F), so the time average is the corresponding finite sum of averaged coefficients times fixed matrices.

2.1step 1.1F2algebra∎

If E=F, the averaged scalar coefficient is 1. If E≠F, then ∣T−1∫0Te−i(E−F)t/ℏ dt∣=∣ℏ(e−i(E−F)T/ℏ−1)−i(E−F)T∣≤2ℏT∣E−F∣→0. Since the finite trace norm is a norm by [F2], the finite matrix sum converges in that norm to ∑EPEρPE. Equal-energy blocks are not removed, so degeneracies are retained.

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Finite-time Kubo formula with norm remainder

Statement

Let H be a complex Hilbert space of finite dimension d≥1, H=H∗ with energy unit J, ℏ>0 with unit J s, β>0 with unit J−1, and let σ=Zβ−1e−βH be the stationary Gibbs density from Finite unitary dynamics and stationary Gibbs states. Let A=A∗ and B=B∗ be matrices, let T>0 be finite in s, let h:[0,T]→R be continuous, and let ϵ∈R be dimensionless; h(t)B has unit J. Put U0(t)=e−itH/ℏ for time t in s, αt(A)=U0(t)∗AU0(t), and Bt=αt(B). Let Wϵ solve Wϵ′(t)=iϵh(t)ℏBtWϵ(t),Wϵ(0)=I, and set Uϵ(t)=U0(t)Wϵ(t) and ρI(t)=Wϵ(t)σWϵ(t)∗. Then Uϵ solves iℏUϵ′(t)=(H−ϵh(t)B)Uϵ(t), Uϵ(0)=I, and ρϵ(t):=Uϵ(t)σUϵ(t)∗ satisfies Tr⁡(ρϵ(t)A)=Tr⁡(ρI(t)αt(A)). Define RAB(u)=iℏTr⁡ ⁣(σ[αu(A),B]),CT=2ℏ∫0T∣h(s)∣ ∥B∥ ds. Then Wϵ(t) is unitary and, for 0≤t≤T, Tr⁡(ρI(t)αt(A))=Tr⁡(σαt(A))+ϵ∫0th(s)RAB(t−s) ds+rϵ(t),∣rϵ(t)∣≤∥A∥(∣ϵ∣CT)2e∣ϵ∣CT2. The initial Gibbs matrix is fixed as ϵ varies. The result is an exact finite-time first variation with a controlled remainder, not a static derivative of a re-prepared Gibbs family. CT and ϵ are dimensionless, and RAB has units [A][B]/(J s).

Facts & Assumptions

Given: The finite-dimensional Hamiltonian and Gibbs density, bounded self-adjoint matrices A,B, continuous real h, ϵ∈R, and T>0.

[F1]

Finite unitary dynamics and stationary Gibbs states: U0 is a unitary group, σ is a positive trace-one matrix commuting with U0(t), and finite trace expectation is cyclically represented in the Heisenberg picture.

[F2]

Finite matrix spectral and state calculus: finite Hermitian matrices have basis-independent spectral functional calculus and the finite trace is cyclic.

[F3]

Finite matrix trace-norm ideal inequalities: ∥YX∥1,∥XY∥1≤∥Y∥∥X∥1, ∣Tr⁡X∣≤∥X∥1, and the finite trace-norm matrix space is complete.

[F4]

Banach-space Volterra and Dyson series with a norm remainder: a strongly continuous bounded coefficient on a Banach space yields a unique Volterra solution and the explicit quadratic remainder; a strongly continuous skew-adjoint Hilbert-space coefficient yields a unitary solution.

Proof

technique · interaction-picture Volterra series and finite trace cyclicity

Given: [F1]–[F4] and the control/observable hypotheses in the Statement.

1.1givenF1F3algebra

The matrix curve t↦Bt is norm-continuous by the finite matrix exponential in [F1]. On the Hilbert space, Kt(ψ)=ih(t)Btψ/ℏ is a strongly continuous skew-adjoint bounded coefficient. On the trace-norm matrix space, Lt(X)=ih(t)[Bt,X]/ℏ is strongly continuous and satisfies ∥Lt(X)∥1≤2∣h(t)∣∥B∥∥X∥1/ℏ by [F3].

2.1givenF1F3F4step 1.1algebra

Apply [F4] to Kt with initial vector ψ to obtain a unitary Wϵ(t), and apply [F4] to Lt with initial matrix σ. The trace-norm solution has linear term ϵ(i/ℏ)∫0th(s)[Bs,σ]ds and remainder norm at most (∣ϵ∣CT)2e∣ϵ∣CT/2, since ∥σ∥1=1. Differentiating the finite matrix product Wϵ(t)σWϵ(t)∗ shows it solves the same commutator equation; uniqueness in [F4] identifies it with that trace-norm solution.

3.1givenF1F2step 2.1algebra

The product rule and U0(t)Bt=BU0(t) give iℏ(U0Wϵ)′=HU0Wϵ−ϵh(t)BU0Wϵ, so Uϵ solves the displayed controlled Schrödinger equation. Since Uϵ=U0Wϵ, cyclicity of the finite trace gives Tr⁡(UϵσUϵ∗A)=Tr⁡(WϵσWϵ∗αt(A)).

3.2givenF1F2step 2.1algebra

Applying Tr⁡(⋅ αt(A)) to the linear term, cyclicity [F2] gives Tr⁡([Bs,σ]αt(A))=Tr⁡(σ[αt(A),Bs]). Since Bs=αs(B) and αt(A)=αs(αt−s(A)), stationarity of σ from [F1] turns this into Tr⁡(σ[αt−s(A),B]). This is exactly the convolution in the Statement.

4.1F1F2F3step 2.1step 3.2algebra∎

The trace-norm remainder from step 2.1 changes the expectation by at most ∥A∥ times its trace norm, by [F3] and ∥αt(A)∥=∥A∥. This gives the displayed bound. For self-adjoint A,B, Tr⁡(σ[αu(A),B]) is purely imaginary by cyclicity and adjoints, so RAB(u) is real.

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Arbitrarily late finite phase recurrences

Statement

Let H=H∗ with energy unit J act on a finite-dimensional complex Hilbert space, let ℏ>0 have unit J s, and let U(t)=e−itH/ℏ for time t measured in s. For every time unit t0>0 measured in s, there is a sequence tn→+∞ and phases λn∈C, ∣λn∣=1, such that ∥U(tn)−λnI∥→0, where ∥T∥:=sup⁡{∥Tv∥:∥v∥≤1} is the operator norm induced by the Hilbert-space norm. Consequently, for every density matrix ρ and bounded observable A, the expectation Tr⁡(U(tn)ρU(tn)∗A) tends to Tr⁡(ρA). If H has only one distinct energy, exact recurrences occur at every time.

Facts & Assumptions

Given: A finite-dimensional complex Hilbert space, H=H∗, ℏ>0, and a fixed t0>0.

[F1]

Finite unitary dynamics and stationary Gibbs states: the distinct real eigenvalues of H define the spectral unitary group U(t)=e−itH/ℏ.

Proof

Given: The finite-dimensional spectrum and unitary group above.

1.1givenF1construct

If the Hilbert space is zero-dimensional, its unique endomorphism is the identity and U(t)=I; take tn=nt0 and λn=1, so every operator-norm error is zero. No density operator exists on that space, making the density consequence vacuous there. On a nonzero space, if H has one distinct energy E1, then U(t)=e−itE1/ℏI, which proves the exact-recurrence clause. Otherwise list its r≥2 distinct energies as E1,…,Er and put θj=(Ej−E1)t0/(2πℏ) for 2≤j≤r. For each integer M≥1, partition the torus [0,1)r−1 into Mr−1 half-open cubes of side 1/M and consider the Mr−1+1 points kθ mod Zr−1 for 0≤k≤Mr−1. Two lie in the same cube, so their nonzero integer difference qM satisfies 1≤qM≤Mr−1 and each qMθj is within 1/M of an integer.

2.1step 1.1algebra

The eigenvalue phase ratios of U(qMt0) to its E1 phase therefore differ from 1 by at most 2π/M, since ∣eix−1∣≤∣x∣. The difference U(qMt0)−λMI is diagonal in the energy basis, so its induced operator norm is the maximum modulus of its diagonal entries and is at most 2π/M, for λM=e−iqME1t0/ℏ. If the positive integers qM are unbounded, choose a subsequence tending to infinity; its times and phase errors give the required sequence. If they are bounded, some fixed positive integer q occurs for arbitrarily large M; then every qθj is an integer, so U(qt0)=λI exactly and its positive integer multiples give exact arbitrarily late recurrences.

3.1step 2.1algebra∎

For any density ρ, the expectation difference is bounded by ∥U(tn)∗AU(tn)−A∥≤2∥A∥∥U(tn)−λnI∥, because scalar phases cancel in conjugation. The bound tends to zero by step 2.1.

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Bounded-commutator graph-domain Schrödinger response

Statement

Assume the Axiom of Choice. Let H≠{0} be a separable complex Hilbert space, H=H∗ a densely defined Hamiltonian on D(H) with unit J, ℏ>0 with unit J s, ρ a positive trace-class density with Tr⁡ρ=1 and ρU0(t)=U0(t)ρ, and A=A∗∈B(H). Fix a reference energy E0>0 in joules and equip D(H) with the graph norm ∥ψ∥G:=∥ψ∥+∥Hψ∥/E0. Let B=B∗∈B(H) with unit [B]. Assume B(D(H))⊆D(H) and that [H,B]ψ=HBψ−BHψ on D(H) extends to a bounded operator C on H. Let h:[0,T]→R be continuous for finite T>0 with h(t)B in J, and let ϵ∈R be dimensionless. Then the bounded-observable response and remainder from Trace-class bounded-observable response hold. In addition, with U0(t)=e−itH/ℏ, Bt=U0(t)∗BU0(t), and Wϵ′(t)=iϵh(t)BtWϵ(t)/ℏ, Wϵ(0)=I, the interaction-picture propagator maps D(H) onto itself, and Ψ(t)=U0(t)Wϵ(t)ψ is a strong solution on [0,T] for each ψ∈D(H), meaning that Ψ:[0,T]→H belongs to C([0,T];D(H)) for the graph norm and to C1([0,T];H), satisfies Ψ(0)=ψ, and satisfies iℏΨ′(t)=(H−ϵh(t)B)Ψ(t) for every t∈[0,T] (with one-sided derivatives at the endpoints). No domain-preservation claim is made for a general bounded B without the stated commutator hypothesis.

Facts & Assumptions

Given: The Axiom of Choice; self-adjoint H; bounded self-adjoint B preserving D(H); bounded extension C of [H,B]; continuous real h; and the trace-class response inputs from Trace-class bounded-observable response.

[A1]

The Axiom of Choice: full Choice is assumed by the unbounded spectral calculus and carried from the normal-state response theorem.

[F1]

Trace-class bounded-observable response: for bounded observables and a trace-class density commuting with U0(t), the response formula holds with the stated finite-time remainder, without an energy or entropy moment assumption.

[F2]

A self-adjoint operator generates a strongly continuous unitary group: U0(t) is strongly continuous, preserves D(H), and differentiates there; its parameter is rescaled by −t/ℏ from the supplier's eisH convention.

[F3]

Symmetric, self-adjoint and essentially self-adjoint operators: a self-adjoint operator is densely defined, closed, and equals its adjoint.

[F4]

Banach-space Volterra and Dyson series with a norm remainder: on any complete normed space, a strongly continuous bounded coefficient has a unique norm-convergent Volterra solution; the same construction applies to the graph norm once that space is shown complete.

Proof

technique · construct the control evolution on the graph Banach space, then differentiate the Schrödinger-picture product

Given: [A1], [F1]–[F4] and the domain/commutator hypotheses in the Statement.

1.1givenF3construct

Use the graph norm on D(H) fixed in the Statement. If (ψn) is Cauchy in this norm, then ψn→ψ and Hψn→ξ in H; closedness of H from [F3] gives ψ∈D(H) and Hψ=ξ, so the graph norm is complete.

2.1givenF2step 1.1algebra

For Bt=U0(t)∗BU0(t) and ψ∈D(H), invariance and commutation in [F2] give HBtψ=BtHψ+U0(t)∗CU0(t)ψ. Hence Bt is uniformly bounded on the graph space by a constant depending only on ∥B∥,∥C∥,E0. To check graph-norm continuity at t0, the Hilbert-norm part follows from strong continuity of U0; for the H-part use the displayed identity and continuity of t↦BtHψ and t↦U0(t)∗CU0(t)ψ. The latter follows from ∥U0(t)∗CU0(t)ψ−U0(t0)∗CU0(t0)ψ∥≤∥C∥∥U0(t)ψ−U0(t0)ψ∥+∥(U0(t)∗−U0(t0)∗)CU0(t0)ψ∥, whose two terms tend to zero by strong continuity of U0 and the group law.

3.1givenA1F2F4step 1.1step 2.1algebra

Apply [F4] on the graph Banach space with coefficient Kt=ih(t)Bt/ℏ; its Volterra series defines Wϵ(t) on D(H). For any y∈D(H), solve the reversed-time graph equation z′(s)=−ϵKt−sz(s) with z(0)=y on [0,t]; then x(s)=z(t−s) solves the forward equation and Wϵ(t)x(0)=y. Hence Wϵ(t)D(H)=D(H). On the Hilbert space the same coefficient is skew-adjoint, and the Hilbert clause of [F4] gives the unitary propagator used in the Statement; uniqueness identifies both constructions. The domain-preservation conclusion therefore uses the full-Choice spectral group hypothesis [A1] together with [F2], [F4] and the commutator condition.

4.1F2F3step 3.1algebra

For ψ∈D(H), the graph-space Volterra solution makes Wϵ(t)ψ continuous and differentiable in graph norm. Also U0(t) acts continuously on D(H) in graph norm because it is strongly continuous on both ψ and Hψ and commutes with H there. Thus Ψ∈C([0,T];D(H)) in graph norm, and the product rule gives Ψ∈C1([0,T];H) with Ψ(0)=ψ. Using U0(t)Bt=BU0(t) and iℏWϵ′=−ϵh(t)BtWϵ, we obtain iℏΨ′(t)=(H−ϵh(t)B)Ψ(t) for every t∈[0,T], with one-sided derivatives at the endpoints. For each fixed t, H−ϵh(t)B is self-adjoint on D(H): it is symmetric, and if y∈D((H−ϵh(t)B)∗), subtracting the bounded B term in the adjoint functional shows y∈D(H∗)=D(H), proving equality of the adjoint domain.

5.1F1step 4.1∎

The trace-class response assertion is exactly [F1] under its stated density, stationarity, bounded-observable and control hypotheses; step 4.1 adds the strong Schrödinger realization only for the graph-domain class in this Statement. The two conclusions therefore retain their separate hypotheses.

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Adopted isolated prepared unitary model

Physical scope

A specified finite-dimensional, isolated, prepared nonrelativistic quantum subsystem with a fixed Hermitian Hamiltonian and bounded-observable Born expectations; no bath limit, relaxation claim, apparatus model, or empirical realization is asserted.

Postulate

For a specified finite-dimensional complex Hilbert space H, H=H∗ in J, and adopted ℏ>0 in J s, take a prepared finite density matrix ρ0 (positive semidefinite with trace one). For time t measured in s, adopt isolated evolution U(t)=e−itH/ℏ,ρt=U(t)ρ0U(t)∗, and the Born expectation Et[A]=Tr⁡(ρtA) for each bounded self-adjoint matrix observable A. This adopts the finite subsystem's preparation and unitary time evolution as a model assumption. It inherits the full Axiom of Choice convention, stated in The Axiom of Choice, of Normal-state quantum measurement interpretation for the wider Hilbert-space spectral-measure framework, although this finite bounded-observable clause uses no unbounded spectral measurement. No actual apparatus, measured value, thermalization, or infinite-volume Hamiltonian is asserted.

The finite unitary and Gibbs conventions are stated in Finite unitary dynamics and stationary Gibbs states as formulation context; they do not prove that this postulate describes nature.

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Prepared control and expectation convention

Physical scope

An idealized finite-dimensional subsystem with a prescribed continuous bounded control on a finite time interval and a fixed prepared initial state; no apparatus calibration, measured response, re-preparation during control, or universal response law is asserted.

Postulate

On a finite-dimensional subsystem with unperturbed H=H∗ in J, bounded self-adjoint control observable B, ℏ>0 in J s, and finite interval [0,T] with T>0 in s, adopt the idealized controlled Hamiltonian Hϵ(t)=H−ϵh(t)B, where h:[0,T]→R is continuous, ϵ∈R is dimensionless, and h(t)B has unit J. The initial prepared state is held fixed at t=0 as the Gibbs matrix σ=Zβ−1e−βH, β>0 in J−1; the model does not re-prepare a Gibbs state for Hϵ(t). Expectations use the adopted normal-state Born convention of Normal-state quantum measurement interpretation. The full Axiom of Choice convention, stated in The Axiom of Choice, of that wider measurement framework is retained. This is an adopted control model; it makes no claim about a particular device or data.

For the controlled propagator Uϵ satisfying iℏUϵ′(t)=Hϵ(t)Uϵ(t) and Uϵ(0)=I, define ρϵ(t)=Uϵ(t)σUϵ(t)∗ and Eϵ,t[A]=Tr⁡(ρϵ(t)A) for bounded self-adjoint matrices A. Existence and uniqueness of this finite-dimensional propagator are supplied by Finite-time Kubo formula with norm remainder.

The finite-time response theorem Finite-time Kubo formula with norm remainder supplies the exact mathematical response interface used to formulate this postulate. It does not establish the physical applicability of the control model.

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Finite spectral balance and distributional fluctuation response

Statement

Let H be finite-dimensional, H=H∗ with unit J, ℏ>0 with unit J s, β>0 with unit J−1, and σ=Zβ−1e−βH as in Finite unitary dynamics and stationary Gibbs states. Let A=A∗ be a matrix observable, write Hui=Eiui in an orthonormal eigenbasis, ri=e−βEi/Zβ, Aij=⟨Auj,ui⟩, and ωji=(Ej−Ei)/ℏ. Define the finite positive spectral measure SAA=2π∑i,jri∣Aij∣2 δωji, where δν is unit point mass at frequency ν and SAA(−⋅) denotes pushforward under ω↦−ω; ωji has unit s−1. With observable unit [A], the atomic masses of the finite measure SAA have units [A]2. For every smooth compactly supported complex-valued function φ:R→C, the distribution represented by the measure SAA acts as ⟨SAA,φ⟩=∫Rφ(ω) dSAA(ω). In the Fourier convention below, the generalized density SAA(ω) relative to dω has units [A]2 multiplied by seconds; it is a finite sum of Dirac distributions, not an ordinary function density. For time t∈R measured in s, the equilibrium correlation is CAA(t)=Tr⁡(σαt(A)A); its Fourier variable ω is measured in s−1, and its Fourier convention is SAA(ω)=∫ReiωtCAA(t) dt in the distributional sense.

For t≥0, set RAA(t)=iℏTr⁡(σ[αt(A),A]). For ω∈R and regulator η>0, both measured in s−1, define the retarded transform χη(ω)=∫0∞e(iω−η)tRAA(t) dt. With observable unit [A], RAA has units [A]2/(J s) and χη has units [A]2/J. Then χη(ω)=∑i,j(ri−rj)∣Aij∣2ℏ(ωji−ω−iη). As η↓0, its boundary value is the corresponding sum of principal-value real parts and Lorentzian imaginary terms weighted by ri−rj, and distributionally Im⁡χ=12ℏ(1−e−βℏω)SAA(ω). Detailed balance is SAA(−dω)=e−βℏωSAA(dω). Thus, on R∖{0}, Ssym(dω)=ℏcoth⁡ ⁣(βℏω2)Im⁡χ(dω),Ssym=12(SAA+SAA(−⋅)). Any zero-frequency mass of SAA is retained separately: the commutator factor vanishes there, so the formula does not determine that atom or define a value for the singular product with coth⁡ at ω=0.

Facts & Assumptions

Given: The finite-dimensional Hamiltonian, Gibbs matrix, bounded self-adjoint observable, Fourier convention, and positive regulator η above.

[F1]

Finite unitary dynamics and stationary Gibbs states: the finite Hermitian spectral decomposition gives U(t) and the stationary Gibbs matrix σ.

[F2]

Finite matrix spectral and state calculus: finite Hermitian matrices admit basis-independent real spectral decompositions and the finite trace is cyclic.

[F3]

Finite-time Kubo formula with norm remainder: under the fixed Gibbs preparation and control H−ϵh(t)B, the retarded commutator kernel has the sign +i/ℏ and is the finite-time first variation.

[F4]

Lorentzian kernels converge to delta and principal-value distributions: η/(x2+η2) converges to πδ0 and x/(x2+η2) to PV⁡(1/x) on compactly supported C1 test functions, with full dominated-convergence proofs.

Proof

technique · finite spectral expansion, exact retarded transform, and the Lorentzian distribution limits

Given: [F1]–[F4], finite d≥1, β>0, and A=A∗.

1.1givenF1F2constructalgebra

In the eigenbasis of H, αt(A)ij=e−iωjitAij, so CAA(t)=∑i,jri∣Aij∣2e−iωjit and the displayed SAA is its Fourier measure under the stated convention. Swapping i,j in the finite sum changes SAA(−dω) to coefficients rj∣Aij∣2 at ωji; since rj/ri=e−βℏωji, this proves detailed balance. The coefficients of SAA are nonnegative.

2.1F1F2F3step 1.1algebra

Expanding the commutator and swapping indices in its second trace term gives RAA(t)=iℏ∑i,j(ri−rj)∣Aij∣2e−iωjit. For η>0, each term is integrable on [0,∞) and ∫0∞e(i(ω−ωji)−η)tdt=−i/(ωji−ω−iη); multiplying by i/ℏ yields the stated rational expression.

3.1F1F4step 2.1algebra

For each summand, write x=ωji−ω and 1/(x−iη)=x/(x2+η2)+iη/(x2+η2). Applying [F4] after the affine change from ω to x gives the principal-value real part and πδ(ω−ωji) imaginary part. On each atom ω=ωji, detailed balance gives ri−rj=ri(1−e−βℏω), so summing the finite terms proves the distributional commutator relation.

4.1F1step 1.1step 3.1algebra∎

Detailed balance gives Ssym=12(1+e−βℏω)SAA away from zero, while step 3.1 gives Im⁡χ=12ℏ(1−e−βℏω)SAA. Dividing on R∖{0} yields the stated ℏcoth⁡(βℏω/2) factor. At ω=0, the detailed-balance pair has equal Gibbs weights and the commutator coefficient is zero, whereas the positive correlation measure may have a nonzero atom; therefore that atom must be retained separately.

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Absolute convergence of trace-Gibbs bounded correlation series

Statement

Assume the Axiom of Choice. Let H≠{0} be separable, K=K∗ a densely defined Hamiltonian bounded below with energy unit J, and β lie in an open interval I⊂(0,∞) measured in J−1 on which e−sK is trace class for every s∈I. Set Zβ=Tr⁡(e−βK), σβ=Zβ−1e−βK, and U(t)=e−itK/ℏ with ℏ>0 in J s and t in s. By Self-adjoint trace-Gibbs normalization and form-energy optimization, K has a complete orthonormal energy basis (ui), Kui=Eiui, with Gibbs weights ri=e−βEi/Zβ>0 and ∑iri=1. For bounded A,B, put Aij=⟨Auj,ui⟩, Bij=⟨Buj,ui⟩, and ωji=(Ej−Ei)/ℏ. Then CAB(t):=Tr⁡(σβU(t)∗AU(t)B)=∑i,jriAijBjie−iωjit converges absolutely and uniformly on R, with ∑i,jri∣Aij∣∣Bji∣≤∥A∥∥B∥. Consequently SAB:=2π∑i,jriAijBji δωji is a finite complex Borel measure with total variation at most 2π∥A∥∥B∥, and CAB(t)=(2π)−1∫e−iωt dSAB(ω). A Dirac measure δν assigns mass one to the point ν. When A,B carry units [A],[B], the atomic masses of the finite measure SAB have units [A][B]. For every smooth compactly supported complex-valued function φ:R→C, the distribution represented by SAB acts as ⟨SAB,φ⟩=∫Rφ(ω) dSAB(ω). In the Fourier convention, the generalized density SAB(ω) relative to dω has units [A][B] multiplied by seconds; it is a sum of Dirac distributions, not an ordinary function density.

Facts & Assumptions

Given: The Axiom of Choice; the trace-class Gibbs hypotheses in the Statement; bounded operators A,B; and the specified ℏ and β.

[A1]

The Axiom of Choice: assume the full Axiom of Choice for the unbounded self-adjoint spectral theorem.

[F1]

Self-adjoint trace-Gibbs normalization and form-energy optimization: under [A1], self-adjoint K bounded below with e−sK trace class on an open positive interval has 0<Zβ<∞, a faithful normal Gibbs density, and a complete energy eigenbasis with eigenvalues e−βEi/Zβ.

[F2]

Trace-state cyclicity and spectral probability calculus: for a trace-class density σ and bounded X, Tr⁡(σX)=∑iri⟨Xui,ui⟩ with absolute convergence; bounded cyclicity holds only for the trace-class factor and bounded factor.

[F3]

Parseval equivalences for an orthonormal family: for a complete orthonormal basis (uj), ∑j∣⟨v,uj⟩∣2=∥v∥2.

[F4]

Hilbert-adjoint identities and The operator norm as the least bound and as the unit-sphere or unit-ball supremum: ∥A∗∥=∥A∥ and ∥Ax∥≤∥A∥∥x∥ for bounded operators.

[F5]

Cauchy–Schwarz: ∣⟨x,y⟩∣≤∥x∥ ∥y∥, with equality exactly for dependent pairs: for square-summable coefficient sequences, the absolute inner-product sum is bounded by the product of their ℓ2 norms.

Proof

technique · direct spectral expansion with an absolute-summability estimate

Given: [A1], [F1]–[F3], and the bounded matrices of the Statement.

1.1givenA1F1F3F4F5algebra

The eigenbasis and weights in the Statement are provided by [F1], and ∑iri=1 follows from Tr⁡σβ=1. For each fixed i, Parseval [F3] and [F4] give ∑j∣Aij∣2=∥A∗ui∥2≤∥A∥2 and ∑j∣Bji∣2=∥Bui∥2≤∥B∥2. By [F5] and summing the nonnegative bounds over i, ∑i,jri∣Aij∣∣Bji∣≤∥A∥∥B∥.

2.1givenF1F2step 1.1algebra

Apply [F2] to X=U(t)∗AU(t)B. Expanding the diagonal matrix element in the energy basis gives ⟨U(t)∗AU(t)Bui,ui⟩=∑je−i(Ej−Ei)t/ℏAijBji. The absolute bound from step 1.1 justifies the double sum and is independent of t; hence the series converges uniformly by the uniform tail bound and equals the stated trace correlation.

3.1givenstep 1.1step 2.1algebra∎

For each Borel set E⊆R, define SAB(E)=2π∑i,j: ωji∈EriAijBji. Absolute convergence from step 1.1 makes this finite and makes the sum countably additive: for disjoint En, each atom belongs to exactly one En, and the absolutely convergent series may be regrouped. The same bound gives total variation at most 2π∥A∥∥B∥. Integrating the bounded function e−iωt termwise, justified by that absolute sum, gives the stated Fourier relation.

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Trace-Gibbs bounded correlation measure and balance

Statement

Assume the Axiom of Choice. Let H≠{0} be separable, K=K∗ densely defined and bounded below with energy unit J, and let e−sK be trace class for every s in an open interval I⊂(0,∞) measured in J−1. Fix β∈I, Zβ=Tr⁡(e−βK), σβ=Zβ−1e−βK, and U(t)=e−itK/ℏ for ℏ>0 in J s and t in s. For bounded A,B, let CAB and SAB be the correlation function and finite spectral measure defined in Absolute convergence of trace-Gibbs bounded correlation series. Write SBA(−⋅) for the pushforward under ω↦−ω. Then for every bounded Borel test function f with compact support, ∫f(ω) SBA(−dω)=∫f(ω)e−βℏω SAB(dω). The weighted measure on the right extends to a finite complex measure: the reindexed coefficient family is absolutely summable and has the same total-variation bound as SBA. For Hermitian A=B, SAA is a positive finite measure. This is a discrete-spectrum equilibrium correlation identity; it asserts no temporal decay, continuum limit, or ordinary zero-frequency transport coefficient.

Facts & Assumptions

Given: The Axiom of Choice, the self-adjoint trace-Gibbs hypotheses, the bounded observables, and the correlation measure from the Statement.

[A1]

The Axiom of Choice: full Choice is the exact assumption of the unbounded spectral theorem and trace-Gibbs supplier.

[F1]

Self-adjoint trace-Gibbs normalization and form-energy optimization: the stated open-interval trace-class hypothesis yields 0<Zβ<∞, a faithful normal Gibbs density, and a complete discrete energy basis.

[F2]

Absolute convergence of trace-Gibbs bounded correlation series: the bounded correlation has an absolutely summable atomic spectral measure with coefficients riAijBji at ωji=(Ej−Ei)/ℏ.

Proof

technique · reindex the absolutely convergent spectral measure

Given: [A1], [F1]–[F2] and bounded Borel f with compact support.

1.1givenA1F1F2algebra

Under the unbounded spectral convention [A1], apply [F2]: ∫f(ω)SBA(−dω)=2π∑i,jriBijAjif(−ωji). The coefficient family is absolutely summable after multiplication by ∥f∥∞, so interchanging indices i and j is permitted.

2.1givenF1F2step 1.1algebra

Reindexing the sum in step 1.1 gives 2π∑i,jrjAijBjif(ωji). Since rj/ri=e−β(Ej−Ei)=e−βℏωji, this is exactly ∫f(ω)e−βℏωSAB(dω). The absolute sum of the reindexed coefficients equals that defining SBA and is finite by [F2]; compact support also makes the test-function weight bounded. Thus the weighted measure is finite and equals the reflected measure.

3.1F1F2algebra∎

If A=B=A∗, then Bji=Aij‾, so each atom coefficient ri∣Aij∣2 of SAA is nonnegative. The measure is finite by [F2], proving positivity.

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Conditional prepared finite quantum control response

Physical scope

Exact prediction of the specified finite-dimensional isolated-control model under its adopted preparation, unitary-evolution, and Born-expectation postulates; it is not an observation, an apparatus validation, or evidence that the model describes nature.

Statement

Assume the adopted finite isolated model and fixed-preparation control convention of Adopted isolated prepared unitary model and Prepared control and expectation convention. Let T>0 be finite in s, let A=A∗ be a bounded matrix observable, and set αt(A)=eitH/ℏAe−itH/ℏ for time t measured in s. Define RAB(u)=iℏTr⁡ ⁣(σ[αu(A),B]),CT=2ℏ∫0T∣h(s)∣ ∥B∥ ds. Then for 0≤t≤T the model expectation obeys Eϵ,t[A]=Tr⁡(σαt(A))+ϵ∫0th(s)RAB(t−s) ds+rϵ(t),∣rϵ(t)∣≤∥A∥(∣ϵ∣CT)2e∣ϵ∣CT2. Here H and hB have unit J, ℏ has unit J s, t has unit s, β has unit J−1, and ϵ,CT are dimensionless. This is a conditional model prediction for the adopted preparation and dynamics, not a claim that an observed finite dataset must equal the prediction.

Facts & Assumptions

Given: The Axiom of Choice, the two adopted physical postulates, finite T, the matrix observable A, and the stated control h,B.

[A1]

Adopted isolated prepared unitary model: the specified finite prepared state evolves as ρt=U(t)ρ0U(t)∗ and the model expectation of bounded A is Tr⁡(ρtA).

[A2]

Prepared control and expectation convention: the controlled generator is H−ϵh(t)B on [0,T] while the initial Gibbs matrix σ remains fixed.

[F1]

Finite-time Kubo formula with norm remainder: for this fixed initial Gibbs density, the Heisenberg expectation has the displayed retarded commutator response and quadratic finite-time remainder.

[A3]

The Axiom of Choice: the full Choice convention is carried from the adopted normal-state measurement framework; no step below uses it to derive the finite matrix formula.

Proof

technique · conditional substitution of the adopted model inputs into the finite-time mathematical response theorem

Given: [A1]–[A3], [F1], and the exact finite-dimensional matrices and controls in the Statement.

1.1givenA1A2F1algebra

By [A1] and [A2], the initial state, controlled Hamiltonian, and model expectation are exactly the inputs used by [F1]; the control does not differentiate or replace the initial Gibbs matrix. The controlled density satisfies Tr⁡(ρϵ(t)A)=Tr⁡(ρI(t)αt(A)) by the finite trace identity in [F1]. Applying [F1] with this A,B,h,ϵ,T gives the stated convolution and remainder bound.

2.1givenA1A2A3step 1.1∎

The equation is therefore a deduction within the adopted finite model, conditional on [A1] and [A2]. The full-Choice convention [A3] is inherited from the wider measurement framework, but the finite-matrix calculation in step 1.1 does not need it. The remainder is a mathematical bound; it supplies no measured response, apparatus reliability claim, or unconditional assertion about nature.

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Bounded C-star Dyson response for finite-range spin dynamics

Statement

Use Γ=Zd, d≥1, finite on-site dimension q≥1, and a uniformly bounded finite-range interaction Φ with parameters M≥1, R<∞, κ<∞, and ℏ>0 as in Uniformly bounded finite-range quantum spin interaction. Assume Countable Choice and the exact finite-matrix C∗-identity condition supplied in Finite matrix C-star algebra and density-state duality. Let A be the norm-completed quasi-local spin algebra of Norm-completed quasi-local quantum spin algebra, and let αt be the strongly continuous automorphism group of Strongly continuous thermodynamic spin automorphism group. Let {ρΛ} be consistent positive trace-one local density matrices; write ϕ for their unique state extension supplied by Consistent local densities extend to an algebraic state, and additionally assume ϕ∘αt=ϕ for every t∈R. This is an algebraic state on A, not a trace-class density on an infinite tensor-product Hilbert space.

For A∈A, B=B∗∈A, continuous real h:[0,T]→R, finite T>0, and dimensionless ϵ∈R, put Bt=αt(B) and let Wϵ solve Wϵ′(t)=iϵh(t)ℏBtWϵ(t),Wϵ(0)=I. The C∗-algebra Dyson solution is unitary. Define αtϵ(A)=Wϵ(t)∗αt(A)Wϵ(t), RAB(u)=iℏϕ([αu(A),B]),CT=2ℏ∫0T∣h(s)∣ ∥B∥ ds. Then ϕ(αtϵ(A))=ϕ(αt(A))+ϵ∫0th(s)RAB(t−s) ds+rϵ(t),∣rϵ(t)∣≤∥A∥(∣ϵ∣CT)2e∣ϵ∣CT2. When energy is the interpretation of HΛ and hB, their units are J, t is s, ℏ is J s, and CT is dimensionless. No global trace Hamiltonian, spatial-to-temporal decay implication, or dc coefficient follows.

Facts & Assumptions

Given: Countable Choice, the finite local spin system and interaction, the finite-matrix identity, the completed quasi-local algebra and group, consistent local densities, an invariant extension ϕ, bounded A,B, continuous h, and finite T.

[A1]

The Axiom of Countable Choice (ACω): Countable Choice is used for the norm-completion construction; no full Axiom of Choice is assumed here.

[F1]

Finite matrix C-star algebra and density-state duality: every nonzero finite local matrix algebra with its induced norm satisfies ∥T∗T∥=∥T∥2.

[F2]

Uniformly bounded finite-range quantum spin interaction: Φ(Z) is self-adjoint, vanishes for ∣Z∣>M or diameter above R, has per-site norm sum κ, and defines the free-boundary finite-volume Hamiltonians.

[F3]

Norm-completed quasi-local quantum spin algebra: A is the norm completion of the directed union of finite local matrix algebras, with no selected global tensor-product Hilbert space.

[F4]

Consistent local densities extend to an algebraic state: consistent positive trace-one local densities extend uniquely to a bounded normalized positive functional ϕ on A.

[F5]

Strongly continuous thermodynamic spin automorphism group: under [A1] and [F1]–[F3], the finite-volume dynamics converge to a strongly continuous one-parameter group αt of isometric ∗-automorphisms.

[F6]

Banach-space Volterra and Dyson series with a norm remainder: on a unital C∗-algebra, a norm-continuous skew-adjoint coefficient has a unique unitary Dyson solution; on a Banach space, the Volterra series has the stated norm remainder.

Proof

technique · apply the Volterra series to the dual Banach space of bounded functionals and identify its solution with unitary conjugation

Given: [A1], [F1]–[F6], and the invariant-state condition in the Statement.

1.1givenA1F1F2F3F4F5algebra

The finite-range group application uses Countable Choice [A1], the local matrix C∗ identity [F1], the finite-range interaction [F2], the quasi-local completion [F3], and the exact group conclusion [F5]. The extension ϕ exists by [F4]. Since t↦αt(B) is norm-continuous by [F5], Bt is norm-continuous and Kt∗(ψ)(X):=ih(t)ℏψ([X,Bt]) is a norm-continuous bounded operator on the continuous dual A∗. Its norm is at most 2∣h(t)∣∥B∥/ℏ, because automorphisms are isometric and ∥[X,Bt]∥≤2∥X∥∥B∥. The dual A∗ is complete: a Cauchy sequence of bounded functionals has pointwise scalar limits, and the uniform Cauchy bound passes to that limit in the dual norm.

2.1givenF4F6step 1.1algebra

By [F6], the initial functional ϕ has a unique Volterra solution ψϵ(t) in A∗ with first-order term ϵ∫0tKs∗(ϕ) ds and remainder dual norm at most (∣ϵ∣CT)2e∣ϵ∣CT/2, since ∥ϕ∥=1. The C∗-algebra clause of [F6] gives a norm-differentiable unitary Wϵ. Differentiating X↦ϕ(Wϵ(t)∗XWϵ(t)) shows this functional solves the same dual Volterra equation, so uniqueness gives ψϵ(t)(X)=ϕ(Wϵ(t)∗XWϵ(t)).

3.1givenF5step 2.1algebra

Evaluate the first-order functional term at X=αt(A). It is iϵℏ∫0th(s)ϕ([αt(A),Bs]) ds. The group law gives [αt(A),Bs]=αs([αt−s(A),B]), and invariance of ϕ removes αs. This is the stated convolution.

4.1givenF4step 2.1step 3.1algebra∎

Since ∥αt(A)∥=∥A∥, evaluating the dual-norm remainder from step 2.1 at αt(A) gives the bound in the Statement. If A=A∗ as well as B=B∗, positivity and Hermiticity of ϕ make RAB(u) real.

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Nonzero pure-point equilibrium covariance is not integrable

Statement

Assume the Axiom of Choice and the trace-class Gibbs hypotheses of Trace-Gibbs bounded correlation measure and balance for a self-adjoint Hamiltonian K in J with a complete discrete energy basis and faithful Gibbs density σβ at β>0 in J−1. Let ℏ>0 be in J s, t in s, and let A=A∗ be a nonzero bounded observable with Tr⁡(σβA)=0. Define CAA(t)=Tr⁡(σβU(t)∗AU(t)A),GAA(t)=Re⁡CAA(t),U(t)=e−itK/ℏ. Then neither CAA nor GAA belongs to L1([0,∞)). In particular, the ordinary absolutely convergent isolated-system correlation integral used in a dc Green–Kubo formula does not exist under these hypotheses. This claim concerns discrete-spectrum trace-Gibbs dynamics only; it asserts no failure of temporal decay or transport limits in an infinite-volume or open-system model.

Facts & Assumptions

Given: The Axiom of Choice, a faithful trace-class Gibbs state with a complete energy eigenbasis, a nonzero bounded self-adjoint centered A, and ℏ>0.

[A1]

The Axiom of Choice: full Choice is assumed by the unbounded self-adjoint spectral theorem and trace-Gibbs supplier.

[F1]

Trace-Gibbs bounded correlation measure and balance: for the Gibbs energy basis, CAA(t) has an absolutely summable atomic expansion with nonnegative weights ri∣Aij∣2, whose total is CAA(0)=∑iri∥Aui∥2≤∥A∥2; σβ is faithful.

[F2]

Dominated convergence: on any measure space, pointwise convergence under an integrable majorant permits passage of limits through integrals.

Proof

technique · grouped pure-point frequencies have a nonzero mean-square limit, which contradicts absolute integrability

Given: [A1], [F1], [F2], and the centered nonzero observable in the Statement.

1.1givenA1F1algebra

Group the nonnegative coefficients in [F1] by equal frequency, writing CAA(t)=∑ω∈Ωwωe−iωt with wω≥0 and ∑ωwω=CAA(0)=Tr⁡(σβA2). This sum is strictly positive: in the complete energy basis, Tr⁡(σβA2)=∑iri∥Aui∥2, every ri>0, and A≠0 prevents all Aui from vanishing. It is bounded by ∥A∥2 because each ∥Aui∥2≤∥A∥2 and ∑iri=1.

2.1givenF1F2step 1.1algebra

Absolute summability gives ∑ω,νwωwν<∞ and allows termwise integration of ∣CAA(t)∣2. For each pair, T−1∫0Te−i(ω−ν)tdt tends to 1 if ω=ν and 0 otherwise, and its modulus is at most 1. Apply [F2] to the countable pair set with summable majorant wωwν; then lim⁡T→∞1T∫0T∣CAA(t)∣2dt=∑ωwω2>0. If CAA∈L1([0,∞)), the left side is at most ∥A∥2T−1∫0T∣CAA(t)∣dt→0, because step 1.1 gives ∣CAA(t)∣≤∑ωwω≤∥A∥2. This contradiction proves CAA∉L1.

3.1F1F2step 1.1step 2.1algebra∎

The real part has grouped nonnegative weights gω=(wω+w−ω)/2, with absent frequencies assigned weight zero. They satisfy ∑ωgω=∑ωwω>0 and GAA(t)=∑ωgωe−iωt. Repeating step 2.1 with gω gives lim⁡T→∞T−1∫0TGAA(t)2dt=∑ωgω2>0. If GAA∈L1, then this average is at most ∥A∥2T−1∫0T∣GAA(t)∣dt→0, again a contradiction.

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Integrability-qualified quantum variance Green–Kubo limit

Statement

Assume Countable Choice and the finite-matrix C∗-identity hypothesis used by Bounded C-star Dyson response for finite-range spin dynamics. Use its finite-range spin algebra A, strongly continuous automorphism group αt, and invariant state ϕ obtained from consistent local densities. Let V=V∗∈A satisfy ϕ(V)=0, and define XT=∫0Tαt(V) dt,G(t)=Re⁡ϕ(Vαt(V)). If G∈L1([0,∞)), then lim⁡T→∞ϕ(XT2)2T=D:=∫0∞G(t) dt≥0. For a finite list of centered self-adjoint observables V1,…,Vm, if each symmetrized covariance Gab(t)=12(Re⁡ϕ(Vaαt(Vb))+Re⁡ϕ(Vbαt(Va))) is absolutely integrable on [0,∞), then Dab=∫0∞Gab(t)dt is a real positive semidefinite matrix. For a velocity observable measured in m s−1, D has units m2 s−1; for general V, its units are [V]2 s. The result is a variance of a time-integrated observable, not a joint classical trajectory or a universal transport law.

Facts & Assumptions

Given: Countable Choice and the finite-matrix C∗-identity hypothesis of the finite-range group construction; the invariant state and group of the algebraic response theorem; centered self-adjoint observables; and absolute integrability of the stated covariance functions.

[A1]

The Axiom of Countable Choice (ACω): Countable Choice is the exact choice assumption for the local-algebra completion; no full Axiom of Choice is used.

[F1]

Finite matrix C-star algebra and density-state duality: every finite local matrix algebra has its induced-norm C∗-identity.

[F2]

Bounded C-star Dyson response for finite-range spin dynamics: under [A1], [F1], and the stated finite-range interaction assumptions, αt is a strongly continuous automorphism group on the quasi-local algebra and ϕ is an invariant bounded state.

[F3]

Stationary-state covariance identity for time-integrated observables: for centered self-adjoint observables, the time-integrated symmetrized covariance equals the finite-time symmetrized variance and its matrix is positive semidefinite.

[F4]

Dominated convergence: pointwise convergence under an integrable majorant permits passage of limits through Lebesgue integrals.

Proof

technique · apply the stationary covariance identity and pass to the infinite-time limit by dominated convergence

Given: [A1], [F1]–[F4], the centered observables, and the integrability hypotheses.

1.1givenA1F1F2F3F4algebra

The algebraic group/state hypotheses follow from [A1], [F1], and the exact interaction and state assumptions carried by [F2]; applying the stationary covariance identity [F3] to the scalar observable gives ϕ(XT2)2T=∫0T(1−tT)G(t) dt. Extend the integrand by zero for t>T. For each fixed t≥0 it converges to G(t) as T→∞, and its absolute value is at most ∣G(t)∣, which is integrable by hypothesis. Applying [F4] on [0,∞) yields the limit ∫0∞G(t)dt.

2.1givenF2F3step 1.1algebra

For finite T, XT=XT∗ by [F3], so ϕ(XT2)=ϕ(XT∗XT)≥0. The limit in step 1.1 is therefore nonnegative.

3.1F2F3F4step 1.1algebra∎

For m observables, [F3] gives the finite-time real symmetric covariance matrix with entries Dab(T)=∫0T(1−t/T)Gab(t)dt; for every real vector c, cTD(T)c=ϕ((∑acaXa,T)2)/(2T)≥0. Each entry converges to Dab=∫0∞Gab(t)dt by the same dominated-convergence argument as step 1.1. For any c, cTDc=lim⁡TcTD(T)c≥0, so D is positive semidefinite.

5 · Examples, experiments and counterexamples

None yet.

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