How statement and proof provenance work
The first chip identifies the source of the statement or construction; the second identifies the source of its local proof or verification.
- Literature-sourced: the exact statement appears in a cited source; only wording and notation differ.
- AI-adapted: a semantically identical restatement of literature-sourced material, modulo indexing, notation, and boundary cases adopted by the library.
- AI-generated: a genuinely novel statement formulated by AI, with no source for the claim itself.
These labels describe origin, not correctness: citations and verification chips remain separate evidence.
The Robertson relation for preparation spreads of assigned sharp observables
Conditional statements about the preparation spreads of two assigned sharp observables of the framework in a pure preparation of a unit vector: the weak Robertson bound Delta A Delta B >= |Im<A psi, B psi>| for unit vectors in both domains, the Robertson bound Delta A Delta B >= |<[A,B]psi,psi>|/2 and its anticommutator refinement when the product domains also contain the vector, and the automatic validity of these hypotheses for bounded observables. The statement is a conditional consequence of P1 and P2 and the cited mathematics; it concerns preparation spreads of outcome laws only, and asserts no apparatus error, no disturbance, no joint measurement, no energy-time inequality and no empirical result.
Statement
Adopt the state and composition postulate P1 and the observable and probability postulate P2 in the readings of The state space of the framework: preparations, pure rays and density operators and Assigned sharp observables and the outcome law of the framework (State and composition postulate P1: Hilbert spaces, preparations and composite systems, Observable and probability postulate P2: self-adjoint observables, spectral probability and finite unsharp outcomes), and assume the Axiom of Countable Choice and the Axiom of Choice (The Axiom of Countable Choice (), The Axiom of Choice). Let and be assigned sharp observables with outcome laws and let be their preparation spreads in the reading of Preparation variance and spread of an assigned sharp observable. Let be a unit vector. Whenever , put Then:
(a) Weak form. If , then the means are real, the spreads and are defined, both are read in the units and , and
(b) Robertson form. If in addition , that is and , then the pairing is defined, is purely imaginary, and read in the product unit ; moreover the anticommutator refinement holds, with equality in the refined bound if and only if and are linearly dependent.
(c) Bounded observables. If and are bounded everywhere-defined self-adjoint operators, then clauses (a) and (b) hold for every unit with all hypotheses automatic (A bounded linear operator between normed spaces).
(d) Status and scope. Clauses (a)-(c) are conditional consequences of P1 and P2 and the cited mathematics. They concern the spreads of the two outcome laws in one preparation; they introduce no joint outcome law, no apparatus resolution, no measurement error, no disturbance of the preparation, and no time observable. In particular no energy-time inequality is asserted, and clauses (a)-(c) do not claim that a laboratory procedure realizes either observable or attains the bounds; whether a concrete preparation and apparatus realize the pair and produce the spread is a tested identification under the preparation and apparatus postulate P7.
Facts & Assumptions
Given: The postulates P1 and P2; the Axiom of Countable Choice and the Axiom of Choice; assigned sharp observables , with self-adjoint operators and declared units; a unit vector ; the preparation spreads of Preparation variance and spread of an assigned sharp observable.
Moments and spread. For an assigned sharp observable and a pure preparation of a unit vector , the mean and the second moment of the outcome law exist with and , and the preparation spread is (Mean, second moment and variance of an assigned observable in a preparation clause (a), Mean, second moment and variance of the scalar spectral law clause (c), Preparation variance and spread of an assigned sharp observable clauses (b) and (c)).
Schroedinger-Robertson bound. For symmetric densely defined and a unit with , with real means and centered vectors , , the refined bound and the equality clause hold: , with equality if and only if are linearly dependent, and with ; and (The Schroedinger-Robertson bound in anticommutator form and the Robertson bound on product domains clauses (a)-(d)).
Weak-form identification without products. For symmetric densely defined and a unit , with real means and as above, because with , and the refined Cauchy-Schwarz bound yields (The Schroedinger-Robertson bound in anticommutator form and the Robertson bound on product domains clause (a), Weak-form Robertson uncertainty on a common domain clauses (a), (c)).
Units. The declared unit of an assigned sharp observable and the reading of powers and products of units are those of Dimensions, SI unit conventions and quantity types of the framework; the commutator pairing and the product are read in the product unit (Preparation variance and spread of an assigned sharp observable clause (d)).
Proof
Given: The data of the statement and [F1]-[F4].
[Weak form] Let be a unit vector. By [F1] the means and are real, the spreads and are defined, and they equal the norms of the centered vectors and . By [F3], and , which is (a).
[Robertson form] Assume in addition . Then satisfy the product-domain hypothesis of [F2] at ; combining the Robertson bound and the anticommutator refinement of [F2] with the identifications of [F1] gives the two displays of (b), and the equality clause transfers because the centered vectors there are exactly and . The pairing is purely imaginary by [F2]. This is (b).
[Bounded case] If and are bounded everywhere-defined self-adjoint operators, then and all products are everywhere defined, so the hypotheses of clauses (a) and (b) hold for every unit ; clauses (a) and (b) apply verbatim. This is (c).
[Units and scope] The units are those of [F4]; the preparation spread is the outcome-law spread of Preparation variance and spread of an assigned sharp observable and no apparatus, disturbance, joint-law or time quantity enters steps 1.1-2.1, which is the scope statement (d).
Depends on
The Axiom of Choice
A bounded linear operator between normed spaces
The Axiom of Countable Choice ()
Dimensions, SI unit conventions and quantity types of the framework
Assigned sharp observables and the outcome law of the framework
The state space of the framework: preparations, pure rays and density operators
The state space: density operators, pure and mixed states, and purity
Preparation variance and spread of an assigned sharp observable
Weak-form Robertson uncertainty on a common domain
Mean, second moment and variance of the scalar spectral law
The Schroedinger-Robertson bound in anticommutator form and the Robertson bound on product domains
Observable and probability postulate P2: self-adjoint observables, spectral probability and finite unsharp outcomes
State and composition postulate P1: Hilbert spaces, preparations and composite systems
Mean, second moment and variance of an assigned observable in a preparation
Dependency tree · 2 levels
Sources
- D. Tong, Quantum Mechanics (author-hosted lecture set), Section 3.4.1, printed pages 84-85 (PDF pages 87-88): variance as the spread of the outcome distribution, the derivation of Delta x Delta p >= hbar/2 from [x,p]=i hbar and the position-momentum example
- B. Zwiebach, MIT 8.05 Quantum Physics II (Fall 2013), Chapter 5 'Uncertainty Principle and Compatible Observables', Section 2, printed pages 3-6: the uncertainty inequality (2.14), its commutator-anticommutator refinement (2.28) and the saturation conditions
- G. Teschl, Mathematical Methods in Quantum Mechanics, 1st edition 2009, Section 3.1, printed pages 88-95 (PDF pages 100-107): expectation values, variances and spectral measures of self-adjoint operators