Superactivation, unlockability, and secrecy distribution of bound information

TL;DR

This paper introduces a new example of bound information in a four-party setting, demonstrating its superactivation and unlockability, and its ability to distribute multipartite entanglement.

Contribution

It provides the first explicit four-party bound information example and proves superactivation and unlockability in finite-copy scenarios.

Findings

Bound information exists in a four-party scenario.

Bound information can be superactivated with multiple copies.

Bound entangled states can distribute multipartite secret keys.

Abstract

Bound information, a cryptographic classical analogue of bound entanglement, is defined as classical secret correlations from which no secret key can be extracted. Its existence was conjectured and shown in a multipartite case. In this work, we provide a new example of bound information in a four-partite scenario. Later, using this example, we prove that bound information can be superactivated in a finite-copy scenario and unlockable. We also show that bound entangled states (bound information) can be used to distribute multipartite pure-state entanglement (secret key).