Entanglement map · Claimed

NPT Werner states are two-copy undistillable in every dimension

A recent result, not yet independently confirmed.

A July 2026 preprint proves a partial-trace inequality for matrices of rank at most two. It applies this to claim two-copy undistillability of NPT Werner states in arbitrary local dimension.

Still unknown

No independent confirmation had been found by the check date. Even if correct, it covers two copies, while the existence of NPT bound entanglement needs every number of copies.

Connections

• Part of: Conversion
• Narrows: Do bound entangled states with a negative partial transpose exist?

Sources

• A partial-trace matrix inequality and Werner-state distillability. Z. Song, L. Chen, 2026.
• Five open problems in quantum information. P. Horodecki, Ł. Rudnicki, K. Życzkowski, 2020.

Checked 2026-10-30.