MATHLIBANNEX / EXACT SOURCE

MathlibAnnex.CStarAlgebra.PureState.no_unitaryIntertwiner_selectedRepresentation

Exact source: MathlibAnnex/Analysis/CStarAlgebra/AtomicConstruction/PureAtomic.lean, lines 75–88.

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1import MathlibAnnex.Analysis.CStarAlgebra.PureStateGNS.IrreduciblePure
2import MathlibAnnex.Analysis.CStarAlgebra.AtomicConstruction.AtomicShell
3
4/-!
5# The chosen pure-GNS family as atomic-model source data
6
7This file specializes the generic arbitrary-index shell model to the literal
8root-preserving representatives already selected in `MathlibAnnex.CStarAlgebra.SourceRepresentatives`.
9The remaining flag and shell inputs are representation-local data; no target
10capture statement is assumed.
11-/
12
13set_option autoImplicit false
14set_option maxHeartbeats 800000
15
16noncomputable section
17
18open Filter Topology
19open scoped ComplexOrder ENNReal lp InnerProduct
20
21namespace MathlibAnnex.CStarAlgebra
22
23universe u
24
25variable {A : Type u} [CStarAlgebra A] [PartialOrder A] [StarOrderedRing A]
26
27namespace PureState
28
29/-- The Hilbert fiber of one chosen pure-state GNS representative. -/
30abbrev SelectedGNS (root : PureState A) (j : GNSClass A) :=
31  (representative root j).positiveFunctional.GNS
32
33/-- The chosen irreducible source representation on one selected fiber. -/
34noncomputable def selectedRepresentation (root : PureState A) (j : GNSClass A) :
35    MathlibAnnex.Analysis.CStarAlgebra.Representation A (SelectedGNS root j) :=
36  (representative root j).positiveFunctional.gnsStarAlgHom
37
38/-- The canonical selected unit vector in one chosen GNS fiber. -/
39noncomputable def selectedVector (root : PureState A) (j : GNSClass A) :
40    SelectedGNS root j :=
41  (representative root j).positiveFunctional.gnsCyclicVector
42
43theorem norm_selectedVector (root : PureState A) (j : GNSClass A) :
44    ‖selectedVector root j‖ = 1 :=
45  norm_representative_gnsCyclicVector root j
46
47/-- The canonical vector in a selected GNS fiber realizes its selected pure
48state exactly. -/
49theorem selected_vectorFunctional (root : PureState A) (j : GNSClass A) :
50    MathlibAnnex.Analysis.CStarAlgebra.Representation.vectorFunctional
51      (selectedRepresentation root j) (selectedVector root j) =
52        (representative root j).1 := by
53  apply ContinuousLinearMap.ext
54  intro a
55  exact PositiveLinearMap.inner_gnsCyclicVector_gnsStarAlgHom
56    (representative root j).positiveFunctional a
57
58noncomputable instance SelectedGNS.instNontrivial
59    (root : PureState A) (j : GNSClass A) : Nontrivial (SelectedGNS root j) := by
60  apply nontrivial_of_ne (selectedVector root j) 0
61  intro hzero
62  have hnorm := congrArg norm hzero
63  simpa [norm_selectedVector] using hnorm
64
65/-- Every chosen pure-GNS fiber is irreducible. -/
66theorem isIrreducible_selectedRepresentation (root : PureState A) (j : GNSClass A) :
67    StarAlgHom.IsIrreducible (selectedRepresentation root j) := by
68  apply isIrreducible_starAlgHom_of_isPureState
69    (selectedRepresentation root j) (selectedVector root j)
70    (norm_selectedVector root j)
71    (denseRange_representative_gns_orbit root j)
72  rw [selected_vectorFunctional]
73  exact (representative root j).2
74
75/-- Distinct chosen classes admit no unitary intertwiner. -/
76theorem no_unitaryIntertwiner_selectedRepresentation (root : PureState A)
77    {i j : GNSClass A} (hij : i ≠ j) (e : SelectedGNS root i ≃ₗᵢ[ℂ] SelectedGNS root j) :
78    ¬ StarAlgHom.Intertwines (selectedRepresentation root i)
79      (selectedRepresentation root j)
80      (e : SelectedGNS root i →L[ℂ] SelectedGNS root j) := by
81  intro he
82  apply hij
83  apply representative_injective_on_classes root
84  refine ⟨e, ?_⟩
85  intro a x
86  have hx := congrArg
87    (fun T : SelectedGNS root i →L[ℂ] SelectedGNS root j ↦ T x) (he a)
88  simpa [selectedRepresentation, ContinuousLinearMap.comp_apply] using hx
89
90/-- The arbitrary dependent sum of the literal chosen pure-GNS fibers. -/
91abbrev SelectedAtomicHilbert (root : PureState A) :=
92  MathlibAnnex.Analysis.InnerProductSpace.HilbertSum (SelectedGNS root)
93
94/-- Coordinate inclusion using a local classical equality decision. -/
95noncomputable def selectedEmbedding (root : PureState A) (j : GNSClass A) :
96    SelectedGNS root j →L[ℂ] SelectedAtomicHilbert root := by
97  classical
98  exact MathlibAnnex.Analysis.InnerProductSpace.coordinateEmbedding j
99
100end PureState
101
102namespace AtomicConstruction
103
104open MathlibAnnex.Analysis.CStarAlgebra
105open MathlibAnnex.Analysis.InnerProductSpace
106
107/-- Natural projection-shell data on the chosen pure-GNS family yields the
108actual irreducible atomic model with unitary inter-block generators. -/
109theorem exists_irreducible_pureAtomicShellModel
110    (root : PureState A)
111    (W : PureState.GNSClass A → ℕ →
112      PureState.SelectedAtomicHilbert root →L[ℂ]
113        PureState.SelectedAtomicHilbert root)
114    (U V : PureState.GNSClass A → ℕ →
115      Submodule ℂ (PureState.SelectedAtomicHilbert root))
116    [∀ i n, (U i n).HasOrthogonalProjection]
117    [∀ i n, (V i n).HasOrthogonalProjection]
118    [∀ i, (⨅ n, U i n).HasOrthogonalProjection]
119    [∀ i, (⨅ n, V i n).HasOrthogonalProjection]
120    (hU : ∀ i, Antitone (U i)) (hV : ∀ i, Antitone (V i))
121    (hU0 : ∀ i, U i 0 = ⊤) (hV0 : ∀ i, V i 0 = ⊤)
122    (hInitial : ∀ i n, ((W i n)†).comp (W i n) =
123      Submodule.projectionShell (U i) n)
124    (hFinal : ∀ i n, (W i n).comp ((W i n)†) =
125      Submodule.projectionShell (V i) n)
126    (hUinf : ∀ i, (⨅ n, U i n).starProjection =
127      InnerProductSpace.rankOne ℂ
128        (PureState.selectedEmbedding root i (PureState.selectedVector root i))
129        (PureState.selectedEmbedding root i (PureState.selectedVector root i)))
130    (hVinf : ∀ i, (⨅ n, V i n).starProjection =
131      InnerProductSpace.rankOne ℂ
132        (PureState.selectedEmbedding root root.classOf
133          (PureState.selectedVector root root.classOf))
134        (PureState.selectedEmbedding root root.classOf
135          (PureState.selectedVector root root.classOf))) :
136    ∃ L : PureState.GNSClass A →
137        PureState.SelectedAtomicHilbert root →L[ℂ]
138          PureState.SelectedAtomicHilbert root,
139      (∀ i, L i ∈ unitary
140        (PureState.SelectedAtomicHilbert root →L[ℂ]
141          PureState.SelectedAtomicHilbert root)) ∧
142      (∀ i, L i (PureState.selectedEmbedding root i
143          (PureState.selectedVector root i)) =
144        PureState.selectedEmbedding root root.classOf
145          (PureState.selectedVector root root.classOf)) ∧
146      (∀ i n, (L i).comp (Submodule.projectionShell (U i) n) = W i n) ∧
147      Representation.IsIrreducible
148        (ambientInclusion
149          (atomicRepresentation (PureState.selectedRepresentation root)) L) := by
150  classical
151  simpa [PureState.selectedEmbedding] using
152    (exists_irreducible_atomicShellModel
153    (PureState.selectedRepresentation root)
154    (PureState.isIrreducible_selectedRepresentation root)
155    (fun {i j} hij e ↦
156      PureState.no_unitaryIntertwiner_selectedRepresentation root hij e)
157    root.classOf (PureState.selectedVector root)
158    (PureState.norm_selectedVector root)
159    W U V hU hV hU0 hV0 hInitial hFinal hUinf hVinf)
160
161end AtomicConstruction
162
163end MathlibAnnex.CStarAlgebra
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