lattice-system

Legacy catalogue: Polynomial-basis decomposition for S = 1 (Tasaki §2.1 Problem 2.1.a, S = 1)

Interim authority. This lossless catalogue chunk remains authoritative for formalization status and capstone identification until Issue #5228. The version 1 JSON catalogue is still a non-authoritative prototype.

Interim catalogueSpin foundations and Tasaki Chapter 2

Polynomial-basis decomposition for S = 1 (Tasaki §2.1 Problem 2.1.a, S = 1)

Primary reference: Tasaki, Physics and Mathematics of Quantum Many-Body Systems, §2.1 Problem 2.1.a, p. 15 + solution S.1, p. 493.

Lean name Statement File
spinOneProj{Plus,Zero,Minus} the three diagonal projectors \|ψ^σ⟩⟨ψ^σ\| (σ ∈ {+1, 0, -1}) Quantum/SpinOneDecomp.lean
spinOneProj{Plus,Zero,Minus}_eq_polynomial each diagonal projector equals a polynomial in Ŝ^(3) (Lagrange interpolation) Quantum/SpinOneDecomp.lean
spinOneUnit{01,02,10,12,20,21} the six off-diagonal matrix units \|ψ^τ⟩⟨ψ^σ\| (τ ≠ σ) Quantum/SpinOneDecomp.lean
spinOneUnit{01,12}_eq_polynomial (1/√2) Ŝ^- · P_σ for the two single-step lowering units Quantum/SpinOneDecomp.lean
spinOneUnit{10,21}_eq_polynomial (1/√2) Ŝ^+ · P_σ for the two single-step raising units Quantum/SpinOneDecomp.lean
spinOneUnit02_eq_polynomial (1/2) (Ŝ^-)² · P_+ for the double-step lowering unit Quantum/SpinOneDecomp.lean
spinOneUnit20_eq_polynomial (1/2) (Ŝ^+)² · P_- for the double-step raising unit Quantum/SpinOneDecomp.lean
spinOne_decomposition every 3×3 complex matrix is a linear combination of the 9 matrix units (entry-wise); combined with the polynomial expressions above this gives Tasaki Problem 2.1.a for S = 1 Quantum/SpinOneDecomp.lean

← Pauli-basis decomposition (Tasaki §2.1 Problem 2.1.a, S = 1/2) · Catalogue · S = 1 matrix representations (Tasaki §2.1 eq. (2.1.9)) →