Joint Hilbert-Schmidt Determinantal Moments of Product Form for the Two-Rebit and Two-Qubit and Higher-Dimensional Quantum Systems

TL;DR

This paper derives formulas for joint moments of determinants related to two-rebit and two-qubit quantum states, aiding in understanding their probability distributions and separability properties.

Contribution

It introduces explicit formulas for joint moments of determinant products involving partial transposition, extending previous work and revealing structural patterns in these moments.

Findings

Formulas for joint moments of determinant products are derived.

Structural patterns of the moment formulas are identified.

Plots of the probability distributions are provided.

Abstract

We report formulas for the joint moments of the determinantal products (det{rho})^k (det{rho^PT})^K (k=0, 1, 2,...,N; K = 0, 1, 2, 3, 4) of Hilbert-Schmidt (HS) probability distributions over the two-rebit and (K = 0, 1) two-qubit density matrices rho. Here PT denotes the partial transposition operation of quantum-information-theoretic importance. Each formula is the product of the expression for the moments of (det{rho})^k, k=0,1,2,...,N--already known from work of Cappellini, Sommers and Zyczkowski (Phys. Rev. A 74, 062322 (1996))--and an adjustment factor. The factor is a biproper rational function, with its numerators and denominators both being 3 K-degree polynomials in k. We infer the structure that the denominators follow for arbitrary K in both the two-rebit and two-qubit cases, and the six leading-order coefficients of k of the numerators in the two-rebit scenario.. We also commence an analogous investigation of generic rebit-retrit and qubit-qutrit systems. This research was motivated, in part, by the objective of using the computed moments to well reconstruct the associated HS probabilities (for which we present plots) over the two determinants, and to ascertain--at least to high accuracy--the associated (separability) probabilities of "philosophical, practical and physical" interest that (det{rho^PT})>0.