Simultaneous Measurement and Entanglement

TL;DR

This paper explores how two spatially-separated observers can optimize their quantum state identification strategies using LOCC and Bell pairs, revealing that LOCC often outperforms Bell pairs for distinguishing product states.

Contribution

It demonstrates that LOCC enables optimal discrimination between two product states and shows LOCC generally provides more benefit than Bell pairs in this context.

Findings

LOCC allows optimal discrimination of two product states

LOCC is almost always more beneficial than Bell pairs for distinguishing product states

Using LOCC improves state identification success rates

Abstract

We study scenarios which arise when two spatially-separated observers, Alice and Bob, are try to identify a quantum state sampled from several possibilities. In particular, we examine their strategies for maximizing both the probability of guessing their state correctly as well as their information gain about it. It is known that there are scenarios where allowing Alice and Bob to use LOCC offers an improvement over the case where they must make their measurements simultaneously. Similarly, Alice and Bob can sometimes improve their outcomes if they have access to a Bell pair. We show how LOCC allows Alice and Bob to distinguish between two product states optimally and find that a LOCC is almost always more helpful than a Bell pair for distinguishing product states.