Quantum Communication with a Twist: QKD using Orbital Angular Momentum Photons

Mohaddaseh Maddahi, Farnaz Farman, Alireza Bahrampour

Daniele Cozzolino, Davide Bacco, Beatrice Da Lio +8 more

Quantum communication (QC) concerns the faithful transmission of quantum states between separated parties, and represents a key enabler for many quantum applications, ranging from quantum key distribution (QKD) to distributed quantum computing. However, low information rates and short propagation distances, due to high channel losses and perturbations of the quantum states, limit the development of this field and its practical applications. High-dimensional (Hi-D) quantum communication can address these challenges by adding more information per photon, directly enhancing the information rate and the system's error tolerance. We transmit Hi-D quantum states using photons prepared in four orbital angular momentum (OAM) modes in a 1.2 km long OAM-carrying fiber. This is the first experimental demonstration of Hi-D quantum states transmission using the OAM basis over an optical fiber. Furthermore, we successfully implement a real-time decoy-state Hi-D QKD protocol, and demonstrate the highest secret key rate and longest transmission distance of OAM-QKD presented to date.

Chaojie Wang, Yuanyuan Chen, Lixiang Chen

The orbital angular momentum (OAM) carried by twisted photons provides a promising playground for high-dimensional quantum information processing. While Bell-state measurement is the cornerstone for various quantum information applications, the deterministic discrimination of the complete high-dimensional Bell states with linear optics remains relatively unexplored in the OAM state space. Here, we demonstrate a theoretical scheme for the complete four-dimensional OAM Bell-state measurement by using the single-photon hyperentangled state analyzer, in which the auxiliary two-dimensional polarization entanglement and two-dimensional path entanglement are utilized. Our scheme offers an alternative route toward enhancing the channel capacity in quantum communication and increasing the robustness against deleterious noise in practical experiments with twisted photons.

Sonja Franke‐Arnold, John Jeffers

SPILLER

Felix Hufnagel, Mikka Stasiuk, Xiaoqin Gao +4 more

We have shown the versatility of orbital angular momentum by performing two new quantum communication protocols: a high-dimensional extension to the two-dimensional round robin differential phase shift QKD, and high-dimensional quantum encryption with certified deletion.