Controlled Quantum Secret Sharing

Abstract

We present a new protocol in which a secret multiqubit quantum state $\ketΨ$ is shared by $n$ players and $m$ controllers, where $\ketΨ$ is the encoding state of a quantum secret sharing scheme. The players may be considered as field agents responsible for carrying out a task, using the secret information encrypted in $\ketΨ$, while the controllers are superiors who decide if and when the task should be carried out and who to do it. Our protocol only requires ancillary Bell states and Bell-basis measurements.