Two-Space Projective Strategies: Direct-Sum State Blocks #
This module contains the role-register direct-sum carriers and block-state construction used to symmetrize a heterogeneous projective strategy.
Direct-sum role-register helpers #
Direct-sum carrier for the future heterogeneous role symmetrization.
For a two-space strategy with Alice carrier ιA and Bob carrier ιB, the later
symmetrized local space will use this tagged direct sum so that Alice's operators
occupy the Sum.inl block and Bob's operators occupy the Sum.inr block.
Equations
- MIPStarRE.LDT.ProjStrat.LocalCarrierSum ιA ιB = (ιA ⊕ ιB)
Instances For
Local carrier planned for the heterogeneous symmetrization bridge: a role bit
and a direct-sum carrier. This is the direct-sum analogue of the current
same-space target Role × ι in StrategyRole.lean.
Equations
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Reassociate role bits and direct-sum carriers.
This is the public heterogeneous analogue of the same-space role-register
reassociation used internally by StrategyRole.lean. It prepares the target
shape for reindexing block states on
(Role × (ιA ⊕ ιB)) × (Role × (ιA ⊕ ιB)).
Equations
- One or more equations did not get rendered due to their size.
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Direct-sum block states for heterogeneous role symmetrization #
Embed an operator on Alice's and Bob's original tensor product into the
(Sum.inl _) × (Sum.inr _) block of the direct-sum tensor product.
Equations
- One or more equations did not get rendered due to their size.
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Embed an operator on Bob's and Alice's original tensor product into the
(Sum.inr _) × (Sum.inl _) block of the direct-sum tensor product.
Equations
- One or more equations did not get rendered due to their size.
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Swap an operator on ιA × ιB to one on ιB × ιA.
Equations
- MIPStarRE.LDT.ProjStrat.heterogeneousSwapDensity X = (Matrix.reindex (Equiv.prodComm ιA ιB) (Equiv.prodComm ιA ιB)) X
Instances For
Lean-only: Tensor products commute with the heterogeneous swap map.
Paper origin: references/ldt-paper/inductive_step.tex:40-66; this is the
matrix-index identity used to identify the two role-register sectors in the
heterogeneous symmetrization.
Place a direct-sum bipartite operator in a chosen pair of role sectors.
Equations
- One or more equations did not get rendered due to their size.
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Distinct role-pair sectors of the direct-sum role register are orthogonal.
Normalizing scalar for the direct-sum heterogeneous role-register state.
Equations
- MIPStarRE.LDT.ProjStrat.roleRegisterDensityScale ιA ιB = 2 * ↑(Fintype.card (MIPStarRE.LDT.ProjStrat.LocalCarrierSum ιA ιB)) ^ 2 / (↑(Fintype.card ιA) * ↑(Fintype.card ιB))
Instances For
Heterogeneous role-register symmetrization of a two-space bipartite state.
The state lives on Role × (ιA ⊕ ιB) on each side. Its occupied sectors are
A/B, carrying the original density in the Sum.inl × Sum.inr direct-sum
block, and B/A, carrying the swapped density in the Sum.inr × Sum.inl block.
The scalar compensates for normalized trace on the enlarged direct-sum carrier.
Normalization and the LDT goodness comparison are separate lemmas.
Equations
- One or more equations did not get rendered due to their size.
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Block-diagonal operator on ιA ⊕ ιB, with Alice's block in the
Sum.inl sector and Bob's block in the Sum.inr sector.
This is the matrix-level direct sum that will underlie symmetrized measurements
such as
|0⟩⟨0| ⊗ A^A + |1⟩⟨1| ⊗ A^B from
references/ldt-paper/inductive_step.tex:55-59.
Equations
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Direct-sum blocks are additive in the two diagonal blocks.
A direct sum of positive semidefinite operators is positive semidefinite.
Finite sums commute through direct-sum blocks.
This is the completeness calculation for block-diagonal measurements: if Alice's and Bob's effects each sum to their local totals, then the direct-sum effects sum to the direct sum of those totals.
Role-blocked operator on Role × (ιA ⊕ ιB).
The first block is used when the role register is Role.A; the second block is
used when the role register is Role.B. This is the direct-sum scaffold for the
paper's symmetrized measurements in inductive_step.tex:55-59.
Equations
- One or more equations did not get rendered due to their size.
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Role-register blocks are additive in their two role sectors.
A role block of positive semidefinite operators is positive semidefinite.
Finite sums commute through role-register blocks.
This is the role-sector analogue of localDirectSumBlock_finset_sum and is the main
completeness calculation for role-blocked measurements.