An Explicit Scott-Type Bound for Absolutely Maximally Entangled States with Arbitrary Defect

2026-06-01Information Theory

Information Theory
AI summary

The authors study special quantum states called absolutely maximally entangled (AME) states, important in quantum computing tasks like secret sharing and error correction. Previous work showed that AME states can't exist if the number of particles is too large, and more recent work looked at "defective" AME states, which are slightly less entangled. The authors solve a conjecture about how big these defective AME states can be, providing exact limits for any amount of defect. Their results also improve known bounds for related quantum error-correcting codes. They achieved this using mathematical programming techniques to prove that certain states cannot exist.

Absolutely Maximally Entangled (AME) statesk-uniform statesMultipartite entanglementQuantum secret sharingQuantum error correctionQuantum Singleton boundMacWilliams identitiesLinear programmingDefective AME statesQuantum codes
Authors
Shixuan Zeng, Xiande Zhang
Abstract
Absolutely maximally entangled (AME) states and, more generally, $k$-uniform states in $(\C^q)^{\otimes n}$ are central objects in multipartite entanglement theory, with applications to quantum secret sharing, quantum masking, and quantum error correction. In the extremal case $k=\lfloor n/2\rfloor$, Scott (2004) proved a sharp nonexistence bound showing that AME states cannot exist once the number of parties $n$ exceeds a threshold of order $2q^{2}$ (with a parity dependence on $n$), where $q$ is the local dimension. Recently, Ning et al.\ studied \emph{defective} AME states (i.e., $k=\lfloor n/2\rfloor-l$ with $l>0$), gave explicit Scott-type bounds for defects $l=1,2$ and conjectured a general $(2l+2)q^{2}+o(q^{2})$ behavior. In this paper, we solve this conjecture and establish a fully explicit Scott-type upper bound for AME states with arbitrary defect $l\ge 0$, yielding Scott's bound for $l=0$ and Ning et al.'s bounds for $l=1,2$ as special cases. Equivalently, this gives nonexistence bounds for one-dimensional pure quantum error-correcting codes near the quantum Singleton regime. The proof uses a truncated MacWilliams linear-programming system and an explicit infeasibility certificate. As a direct application, we derive explicit asymptotic upper bounds on $k/n$ for fixed local dimension $q$, improving the implicit upper bounds given by Ning et al.