We construct representation of the Separated Variables (SoV) for the quantum SL(2,R) Heisenberg closed spin chain and obtain the integral representation for the eigenfunctions of the model. We calculate explicitly the Sklyanin measure defining the scalar product in the SoV representation and demonstrate that the language of Feynman diagrams is extremely useful in establishing various properties of the model. The kernel of the unitary transformation to the SoV representation is described by the same "pyramid diagram" as appeared before in the SoV representation for the SL(2,C) spin magnet. We argue that this kernel is given by the product of the Baxter Q-operators projected onto a special reference state.
In
3×3 dimensions, entangled mixed states that are positive under partial transposition (PPT states) must have rank at least four. They are well understood. We say that they have rank
(4,4) since a state
ρ and its partial transpose
ρP both have rank four. The next problem is to understand the extremal PPT states of rank
(5,5). We call two states
SL⊗SL-equivalent if they are related by a product transformation. A generic rank
(5,5) PPT state
ρ is extremal, and
ρ and
ρP both have six product vectors in their ranges, and no product vectors in their kernels. The three numbers
{6,6;0} are
SL⊗SL-invariants that help us classify the state. We have studied numerically a few types of nongeneric rank five PPT states, in particular states with one or more product vectors in their kernels. We find an interesting new analytical construction of all rank four extremal PPT states, up to
SL⊗SL-equivalence, where they appear as boundary states on one single five dimensional face on the set of normalized PPT states. We say that a state
ρ is
SL⊗SL-symmetric if
ρ and
ρP are
SL⊗SL-equivalent, and is genuinely
SL⊗SL-symmetric if it is
SL⊗SL-equivalent to a state
τ with
τ=τP. Genuine
SL⊗SL-symmetry implies a special form of
SL⊗SL-symmetry. We have produced numerically a random sample of rank
(5,5) SL⊗SL-symmetric states. About fifty of these are of type
{6,6;0}, among those all are extremal and about half are genuinely
SL⊗SL-symmetric.
This paper addresses a new characterization of Sudarshan's diagonal representation of the density matrix elements
ρ(z′,z), derivedfrom
(q;l,λ)−deformed boson coherent states.The induced
ρ(z′,z) self-reproducing property with the associated self-reproducing kernel
K(z′,z) is computed and analyzed. An explicit construction of novel classes of generalized continuous
(q;l,λ)−Hermite polynomials is provided with the corresponding recursion relations and exact resolution of the moment problems giving their orthogonality weight functions. Besides, the Berezin-Klauder-Toeplitz quantization of classical phase space observables and relevant normal and anti-normal forms are investigated and discussed.