The support lower bound can fall below PPT distillable entanglement
OpenQAlgorithms.Papers.Independent.Intakethird100.P90.eta_not_tightAll systems are finite-dimensional complex Hilbert spaces with fixed orthonormal product bases and positive local dimensions. A state is a positive semidefinite operator of trace one. All logarithms are base two and all operational rates are measured in standard Bell pairs (ebits) per input copy, with deterministic operations and error tending to zero. Write for distillable entanglement and entanglement cost under completely PPT-preserving CPTP operations; an explicit LOCC subscript denotes unrestricted two-way local operations and classical communication.
Let project onto the three-dimensional antisymmetric subspace of , and put , where swaps the qutrits. Let be the support-sandwich bound of Eq. (4). Then
The new evaluation of illustrates failure of tightness. The paper explicitly credits the equal operational values to Ref. [12]. This rank-three state is distinct from the rank-two class in the main result.
import Definitions.Def_QAlgorithms_Papers_Independent_Intakethird100_P90
noncomputable section
open scoped Matrix ComplexConjugate ComplexOrder
namespace QAlgorithms.Papers.Independent.Intakethird100.P90
attribute [local instance] Classical.propDecidable Classical.decEq
open QAlgorithms
open QAlgorithms.Papers.Independent.Dependency50.P36
(relativeEntropy rains target canonicalMatrix allowed pptDistillable)
open QAlgorithms.Papers.Independent.Information100.P04 (gamma copies IsPPT)
open QAlgorithms.Papers.Independent.Next46.P42 (regroupProduct)
open QAlgorithms.Papers.Independent.Information100.P06 (supportProjection)
open QAlgorithms.Papers.Independent.Information100.P21 (FiniteLOCC)
open QAlgorithms.Papers.Independent.Gap48.P32 (antisymmetricQutrit)
/-- arXiv:1606.09421v3, PDF p.5, Discussion: the rank-three example.
The new E_eta evaluation is separated in provenance from the operational
value log2(5/3), which this paragraph explicitly credits to Ref.[12]. -/
theorem eta_not_tight :
etaEntanglement antisymmetricQutrit = Real.logb 2 (3/2 : ℝ) ∧
(etaEntanglement antisymmetricQutrit : EReal) < pptDistillable antisymmetricQutrit ∧
pptDistillable antisymmetricQutrit = (Real.logb 2 (5/3 : ℝ) : EReal) ∧
asymptoticEntanglementCost false antisymmetricQutrit = (Real.logb 2 (5/3 : ℝ) : EReal) := by sorry
end QAlgorithms.Papers.Independent.Intakethird100.P90
end
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What the Lean code literally says, in plain math · gpt-6.1-sol
Let be the matrix on whose entries are
Write and . Let be the functional-calculus value at of the scalar function that is zero at zero and one elsewhere, and define , where is the infimum of over Hermitian satisfying and . A PPT channel means a map for which both and have finite Kraus representations with the sum of equal to the identity. Define as the extended-real supremum of nonnegative real such that, for every , all sufficiently large natural admit a PPT channel taking within trace norm of ; define as the extended-real infimum of nonnegative real such that, for every , all sufficiently large positive admit a natural and a PPT channel taking within trace norm of . Here tensor-power basis indices are relabelled by the specified finite-set bijections, and has entry when both its row and column pairs have equal components, and zero otherwise; and rate zero are allowed. The assertion is
with real values embedded into the extended real numbers where required.
Confirmed by the mission captain (proposal self-audit).
Confirmed by the moderator at approval.