Superdense Coding and Stabiliser Codes with Ising-coupled Entanglement

Abstract

A new class of quantum states is introduced by demanding that the computational measurement statistics approach the Boltzmann distribution of higher-order strongly coupled Ising models. The states, referred to as $n$-coupled states, are superpositions of even or odd parity $n$-qubit states, generalize Bell states, and form an orthonormal basis for the $n$-qubit Hilbert space. For any $n$, the states are maximally connected and locally maximally entangled. It is proven that the $n$-qubit W and GHZ multipartite entanglement classes have vanishing hyperdeterminant for all $n\geq 3$ and $n\geq 4$, respectively, and that the $n$-coupled states fall in the latter. Still, multiple novel protocols for multi-party secure dense coding and stabiliser code construction are presented, which rely on the structure of $n$-coupled states as well as symmetry-breaking phase perturbations.