A gap between holographic and quantum mechanical extreme rays of the subadditivity cone

TL;DR

This paper demonstrates that for six or more parties, certain extreme rays of the subadditivity cone are realizable by quantum states but not by holographic states, revealing fundamental differences in their structure.

Contribution

It provides explicit counterexamples showing a gap between holographic and quantum extreme rays, challenging previous conjectures about their equivalence.

Findings

Existence of quantum realizable but holographically forbidden extreme rays for six or more parties

Counterexample to the conjecture linking holographic and quantum extreme rays

Reveals deeper holographic constraints on subsystem independence

Abstract

We show via explicit construction that for six or more parties, there exist extreme rays of the subadditivity cone that can be realized by quantum states, but not by holographic states. This is a counterexample to a conjecture first formulated in arXiv:2204.00075, and implies the existence of deep holographic constraints that restrict the allowed patterns of independence among various subsystems beyond the universal quantum mechanical restrictions.