Li-Qiao Entanglement Constraints Confirming the Entanglement Probability of $\frac{13}{27}$ for the Two-Qutrit Hiesmayr-Löffler Magic Simplex of Bell States
Li-Qiao Entanglement Constraints Confirming the Entanglement Probability of 2713 for the Two-Qutrit Hiesmayr-Löffler Magic Simplex of Bell States
We obtain formulas (bot. p. 12)--including 1212 and 98014(2423π−1311)--for the eight atoms (Fig. 11), summing to 1, which span a 256-dimensional three-set (P, S, PPT) entanglement-probability boolean algebra for the two-qutrit Hiesmayr-Loffler states. PPT denotes positive partial transpose, while P and S provide the Li-Qiao necessary and}sufficient conditions for entanglement. The constraints ensuring entanglement are s>916≈1.7777 and p>318⋅715⋅13227≈5.61324⋅10−15. Here, s is the square of the sum (Ky Fan norm) of the eight singular values of the 8×8 correlation matrix in the Bloch representation, and p, the square of the product of the singular values. In the two-ququart Hiesmayr-Loffler case, one constraint is s>49≈2.25, while 2134324≈1.2968528306⋅10−29 is an upper bound on the appropriate p value, with an entanglement probability ≈0.607698. The S constraints, in both cases, prove equivalent to the well-known CCNR/realignment criteria. Further, we detect and verify--using software of A. Mandilara--pseudo-one-copy undistillable (POCU) negative partial transposed two-qutrit states distributed over the surface of the separable states. Additionally, we study the best separable approximation problem within this two-qutrit setting, and obtain explicit decompositions of separable states into the sum of eleven product states. Numerous quantities of interest--including the eight atoms--were, first, estimated using a quasirandom procedure.
First, we considerably simplify an initially quite complicated formula -- involving dilogarithms. It yields the total bound entanglement probability (≈0.0865542) for a qubit-ququart (2×4) three-parameter model, recently analyzed for its separability properties by Li and Qiao. An "archipelago" of disjoint bound-entangled regions appears in the space of parameters, somewhat similarly to those recently found in our preprint, "Jagged Islands of Bound Entanglement and Witness-Parameterized Probabilities". There, two-qutrit and two-ququart Hiesmayr-L{ö}ffler "magic simplices" and generalized Horodecki states had been examined. However, contrastingly, in the present study, the entirety of bound entanglement--given by the formula obtained--is clearly captured in the archipelago found. Further, we "upgrade" the qubit-ququart model to a two-ququart one, for which we again find a bound-entangled archipelago, with its total probability simply being now 7291(473−512log(1627)(1+log(1627)))≈0.0890496. Then, "downgrading" the qubit-ququart model to a two-qubit one, we find an archipelago of total non-bound/free entanglement probability 21.
We report several witness-parameterized families of bound-entangled probabilities. Two pertain to the d=3 (two-qutrit) and a third to the d=4 (two-ququart) subsets analyzed by Hiesmayr and L{ö}ffler of "magic" simplices of Bell states. The Hilbert-Schmidt probabilities of positive-partial-transpose (PPT) states--within which we search for bound-entangled states--are 2738π≈0.537422 (d=3) and 21+83log(2−3)≈0.404957 (d=4). We obtain bound-entangled probabilities of −94+2734π+6log(3)≈0.00736862 and 1134−204+7log(7)+1683cos−1(1411)≈0.00325613 (d=3) and 278log(2)−28859≈0.00051583 and 171724csch−1(178)−54491≈0.00218722 (d=4). Thus, the total entanglement probability appears to equal (1−2738π)+812(43π−21)=2713≈0.481481.) The families, encompassing these results, are parameterized using generalized Choi and Jafarizadeh-Behzadi-Akbari witnesses. The same bound-entangled probability was achieved with both--the sets ("jagged islands") detected having void intersection. The entanglement (bound and "non-bound"/"free") probability for both was 61≈0.16667, while their union and intersection gave 92≈0.22222 and 91≈0.11111. Further, we examine generalized Horodecki states, as well as estimating PPT-probabilities of approximately 0.39339 (very well-fitted by 2557π≈0.39338962) and 0.115732 ( for the original (8- [two-qutrit] and 15 [two-ququart]-dimensional) magic simplices themselves.