Compare centered and uncentered few-moment realignment criteria

Determine whether, for every nonzero positive semidefinite bipartite operator with nonzero centered-normalization factor, the condition that the normalized centered realignment moments satisfy \(\alpha(r(\tilde X/\sqrt{G(X)}))\leq1\) implies that the normalized uncentered realignment moments satisfy \(\alpha(r(X/t_X))\leq1\).

Background

The enhanced realignment criterion is shown earlier to imply the standard realignment criterion at the level of trace norms. The paper then introduces the discrete moment functional α\alpha, which gives optimal trace-norm information from finitely many even singular-value moments.

Whether the same implication persists after replacing the full trace norms by the corresponding finite-moment conditions is left unresolved. The question concerns arbitrary positive semidefinite bipartite operators, subject to the nonzero assumptions needed to define the two normalizations.

References

It is natural to ask whether this also applies to the moment-based criterion, i.e.: $$\forall X \in \mathcal{M}+, \quad \alpha\left(r\left(\frac{\tilde X}{\sqrt{G(X)}}\right)\right) \leq 1 \implies \alpha\left(r\left(\frac{X}{t_X}\right)\right) \leq 1.$$

— Optimal entanglement criteria from trace invariants  (2609.29471 - Mallick et al., 24 Sep 2026) in Section 4, subsection “Inequalities for separable states,” immediately before Section 5