aiqbench analysis
This research establishes a fundamental bipartite partial-trace inequality for low-rank matrices to resolve long-standing questions regarding the distillability of Werner states in quantum information theory. By proving that two-copy undistillable NPT Werner states remain non-distillable even under activation scenarios, the study advances our theoretical understanding of entanglement properties and state manipulation limits.
A partial-trace matrix inequality and Werner-state distillability
arXiv:2607.23416v1 Announce Type: new Abstract: Motivated by the equivalent partial-trace formulations of Werner-state distillability [P. Costa Rico, Lett. Math. Phys. 115, 47 (2025); S.-Y. Qi et al., Phys. Rev. A 110, 012406 (2024)], we prove a bipartite partial-trace inequality for every matrix of rank at most two. As applications, we prove the two-copy undistillability of NPT Werner states in arbitrary local dimension, thereby resolving this open problem highlighted in [P. Horodecki et al., PRX Quantum 3, 010101 (2022)]. We further prove a two-parameter extension of the matrix inequality and show that two individually one-copy-undistillable NPT Werner states cannot activate each other's one-copy distillability. We also resolve the singular-value maximization problem associated with the two-ququart case.
Abstract:Motivated by the equivalent partial-trace formulations of Werner-state distillability [P. Costa Rico, Lett. Math. Phys. 115, 47 (2025); S.-Y. Qi et al., Phys. Rev. A 110, 012406 (2024)], we prove a bipartite partial-trace inequality for every matrix of rank at most two. As applications, we prove the two-copy undistillability of NPT Werner states in arbitrary local dimension, thereby resolving this open problem highlighted in [P. Horodecki et al., PRX Quantum 3, 010101 (2022)]. We further prove a two-parameter extension of the matrix inequality and show that two individually one-copy-undistillable NPT Werner states cannot activate each other's one-copy distillability. We also resolve the singular-value maximization problem associated with the two-ququart case.
9 pages, no figures. The proof of the main result, namely Theorem 5, was completed in June 2026, and the remaining results and manuscript were finalized in the following month
arXiv:2607.23416 [quant-ph]
(or arXiv:2607.23416v1 [quant-ph] for this version)
https://doi.org/10.48550/arXiv.2607.23416 arXiv-issued DOI via DataCite (pending registration)
Full text under the publisher's open licence · 155 words
Related coverage
Two-copy nondistillability of Werner states: sharp partial-trace inequalities and finite-copy extensions
arXiv · Jul 28, 2026
On the two-copy distillability of Werner states and a new partial trace inequality
arXiv · Jul 28, 2026
On the saturated cases of the distillability conjecture
arXiv · Jun 3, 2026
Sharp Plucker Geometry for Three-Copy Werner Distillation
arXiv · Aug 5, 2026