Quantum secret sharing is the procedure of securely distributing information between multiple parties by exploiting the features of quantum mechanics. Many variants exist, but in this work, we report a high-dimensional realization of a single-photon secret sharing scheme for distributing classical keys amongst many nodes. The implementation, which makes use of twisted light, is realized for as high as 11 dimensions and for as many as 10 participants: the highest reported to date and which is easily extendable to even higher dimensions and many participants. Such a result is an important first step towards a future quantum network.
Quantum secret sharing (QSS) is a cryptographic multiparty communication technique in which a secret is divided and shared among N parties and then securely reconstructed by (N-1) cooperating parties, making it perfect for storing and sharing highly sensitive data. Challenges in high dimensional state preparation, transformation and detection, the key steps of any QSS protocol, have so far hindered experimental realisation. Here, by taking advantage of the high-dimensional encoding space accessible by a photon's orbital angular momentum, we present a toolbox for realising practical high-dimensional single photon QSS schemes that are easily scalable in both dimension and number of participants. Our implementations realised a new record in both the number of participants (N=10) and the dimensionality (d=11), with the latter facilitating the transfer of 2.89 bits of information per photon. This work is an important step towards securely distributing information across a network of nodes.
In this work, Stokes polarimetery is used to extract the polarization structure of optical fields from only four measurements as opposed to the usual six measurements. Here, instead of using static polarization optics, we develop an all-digital technique by implementing a Polarization Grating (PG) which projects a mode into left- and right-circular states which are subsequently directed to a Digital Micromirror Device (DMD) which imparts a phase retardance for full polarization acquisition. We apply our approach in real-time to reconstruct the State of Polarization (SoP) and intra-modal phase of optical modes.
This Conference Presentation, "Perfect vortex beams and their applications in classical and quantum information processing," was recorded at Photonics West 2020 held in San Francisco, California, United States.