Curator's Take
This article demonstrates a crucial stepping stone toward practical quantum internet infrastructure by successfully implementing quantum secret sharing across three superconducting nodes, where any two parties can reconstruct a secret but no single party can access it alone. The researchers achieved fidelities above the fundamental no-cloning threshold, proving the protocol's security even against a dishonest player with unlimited computational power - a remarkable feat that showcases the inherent security advantages of quantum cryptography. What makes this particularly exciting is the use of superconducting microwave systems, the same technology powering today's quantum computers, suggesting these security protocols could be directly integrated into existing quantum hardware architectures. The demonstrated connections to quantum error correction and dense coding reveal how this work bridges fundamental quantum information theory with practical distributed quantum computing applications.
— Mark Eatherly
Summary
Superconducting microwave quantum networks is a rapidly developing field, enabling distributed quantum computing and holding a promise for hybrid architectures in quantum internet. Quantum secret sharing (QSS) is one of the key protocols for multipartite quantum networks and can provide an unconditionally secure way to share quantum states among $n$ players. Using microwave two-mode squeezed states as an entanglement resource, we experimentally implement a QSS protocol with $n = 3$, where a subset of at least $k = 2$ players must collaborate to faithfully reconstruct the original secret state. We demonstrate reconstructed-state fidelities that surpass the asymptotic no-cloning threshold of $F_\textrm{nc} = 2/3$ and identify a parameter regime that allows for unconditionally secure communication in the presence of an omnipotent dishonest player. Furthermore, we experimentally explore inherent connections between QSS and other important quantum information processing tasks, such as quantum dense coding and elementary quantum error correction of channel erasures. Finally, we discuss extensions of QSS and its relation to the concept of blind quantum computing.