Strong connections between quantum encodings, non-locality and quantum cryptography

TL;DR

This paper explores the fundamental relationships between quantum measurement, non-locality, and cryptography, revealing how quantum encoding strategies influence these phenomena and their applications.

Contribution

It provides new insights into the connections between quantum encodings, non-locality, and cryptography, including a simple proof of the optimal quantum strategy in a key non-local game.

Findings

Proves strong equivalences between quantum encoding, non-locality, and cryptography.

Offers applications demonstrating these connections across quantum information.

Provides a new perspective on quantum measurement and its implications.

Abstract

Encoding information in quantum systems can offer surprising advantages but at the same time there are limitations that arise from the fact that measuring an observable may disturb the state of the quantum system. In our work, we provide an in-depth analysis of a simple question: What happens when we perform two measurements sequentially on the same quantum system? This question touches upon some fundamental properties of quantum mechanics, namely the uncertainty principle and the complementarity of quantum measurements. Our results have interesting consequences, for example they can provide a simple proof of the optimal quantum strategy in the famous Clauser-Horne-Shimony-Holt game. Moreover, we show that the way information is encoded in quantum systems can provide a different perspective in understanding other fundamental aspects of quantum information, like non-locality and quantum cryptography. We prove some strong equivalences between these notions and provide a number of applications in all areas.