Experimental high-dimensional quantum secret sharing with spin-orbit-structured photons

Abstract

Secret sharing allows three or more parties to share secret information which can only be decrypted through collaboration. It complements quantum key distribution as a valuable resource for securely distributing information. Here we take advantage of hybrid spin and orbital angular momentum states to access a high-dimensional encoding space, demonstrating a protocol that is easily scalable in both dimension and participants. To illustrate the versatility of our approach, we first demonstrate the protocol in two dimensions, extending the number of participants to ten, and then demonstrate the protocol in three dimensions with three participants. We reconstruct secrets depicted as images with a fidelity of up to 0.979. Moreover, our scheme exploits the use of conventional linear optics to emulate the quantum gates needed for transitions between basis modes on a high-dimensional Hilbert space, allowing us to exceed the 1 bit per photon limit of two-dimensional protocols. Our work offers a practical approach for sharing information across multiple parties, a crucial element of any quantum network.