Local tests of global entanglement and a counterexample to the generalized area law

Understand

We introduce a technique for applying quantum expanders in a distributed fashion, and use it to solve two basic questions: testing whether a bipartite quantum state shared by two parties is the maximally entangled state and disproving a generalized area law.

• In the process these two questions which appear completely unrelated turn out to be two sides of the same coin.
• Strikingly in both cases a constant amount of resources are used to verify a global property.