The doubled model's quantities are role averages of the model's #
Theorem C of reports/c6b-paper-proofs.md, §4 (Lemma 5), in the vocabulary of the port and of
M: every quantity of the doubled model Doubling.model hM hψ (Co/Doubling/Model.lean) built
from Born probabilities is the average of the same quantity of M over the two ways of assigning
the doubled players' blocks to the two players of M.
An element x of the doubled local algebra Loc M = LocA M × LocB M has the components
compA hM x : 𝒜 and compB hM x : ℬ, its blocks pulled back along the ⋆-isomorphisms of
IsFinitePair.equivA and IsFinitePair.equivB; on the report's local algebra 𝒜 × ℬ, translated
by Doubling.equiv, they are the two coordinates (compA_equiv, compB_equiv).
- Born probabilities (
bornProb_model_eq,bornProb_model_equiv):bornProb_D(x, y) = ½ (bornProb_M(x¹, y²) + bornProb_M(y¹, x²)). - The submeasurement consistency defect (
qBipartiteConsDefect_model): the port'sqBipartiteConsDefectof two submeasurements of the doubled model is the average of the two defectsmax 0 (total − match)ofM, exactly, since both are off-diagonal Born masses. - The disagreement (
dis_model,dis_model_pair) and the inconsistency (inconsistency_model,inconsistency_model_pair) ofMIPRE/Foundations/halve in the same way. A POVMGof the doubled local algebra has the POVMspovmA hM Gof𝒜andpovmB hM Gofℬas components (the report'sG¹,G²), and a POVM of𝒜 × ℬis translated bypovmPair, with components its coordinates (povmA_povmPair,povmB_povmPair).
The players' algebras of M are star-ordered here, as in MIPRE.LIDT.Simul.SoundIn, so that the
components of a positive element are positive and POVMs transport.
The components of the doubled local algebra #
The first component of an element of the doubled local algebra, in 𝒜: its first block,
pulled back along IsFinitePair.equivA.
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The second component of an element of the doubled local algebra, in ℬ: its second block,
pulled back along IsFinitePair.equivB.
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The operator of the first component is the first block.
The operator of the second component is the second block.
The first component of a translated element of 𝒜 × ℬ is its first coordinate.
The second component of a translated element of 𝒜 × ℬ is its second coordinate.
The Born probability of M at two components is the operator Born probability of the
blocks.
Born probabilities #
The role average for Born probabilities (Theorem C of reports/c6b-paper-proofs.md, §4):
bornProb_D(x, y) = ½ (bornProb_M(x¹, y²) + bornProb_M(y¹, x²)).
The role average for Born probabilities, on the report's local algebra 𝒜 × ℬ:
bornProb_D((a, b), (a', b')) = ½ (bornProb_M(a, b') + bornProb_M(a', b)).
The halving of the consistency quantities #
The defect max 0 (total − match) of a nonnegative double sum is its off-diagonal part.
The off-diagonal part of a role-averaged double sum is the average of the two off-diagonal parts, the second with its indices exchanged.
The Born probabilities of M at the components of nonnegative elements are nonnegative.
The total Born probability of two submeasurements of the doubled local algebra, at the components, is the double sum of the outcome Born probabilities.
The submeasurement consistency defect halves (Theorem C, Lemma 5 of
reports/c6b-paper-proofs.md, §4): the port's bipartite defect of two submeasurements of the
doubled model is the average of the two defects max 0 (total − match) of M, at the components
X¹, Y² and Y¹, X².
POVMs #
The first components of a POVM of the doubled local algebra, a POVM of 𝒜 (the report's
G¹).
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The second components of a POVM of the doubled local algebra, a POVM of ℬ (the report's
G²).
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The translation of a POVM of the report's local algebra 𝒜 × ℬ, a POVM of the doubled
local algebra.
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The operators of povmA hM P are the first components of those of P.
The operators of povmB hM P are the second components of those of P.
The operators of povmPair hM P are the translations of those of P.
The first components of a translated POVM of 𝒜 × ℬ are its first coordinates.
The second components of a translated POVM of 𝒜 × ℬ are its second coordinates.
The disagreement halves: the disagreement of two POVMs of the doubled model is the average
of the disagreements of M at their components.
The disagreement halves, for POVMs of the report's local algebra 𝒜 × ℬ.
The inconsistency halves: the inconsistency of two families of POVMs of the doubled model
is the average of the inconsistencies of M at their components.
The inconsistency halves, for families of POVMs of the report's local algebra 𝒜 × ℬ.