Fiber Transport of Entangled Photonic Qudits

Panagiotis Vergyris

Hee Jung Lee, Sang-Kyung Choi, Hee Su Park

Fiber transport of multi-dimensional photonic qudits promises high information capacity per photon without space restriction. This work experimentally demonstrates transmission of spatial qudits through multi-core optical fibers and measurement of the entanglement between two fibers with quantum state analyzers, each composed of a spatial light modulator and a single-mode fiber. Quantum state tomography reconstructs the four-dimension entangled state that verifies the non-locality through concurrences in two-dimensional subspaces and a high-dimensional Bell-type CGLMP inequality.

R. B. Dalton, Nathan K. Langford, M. Harvey +5 more

Stefania Sciara, Hao Yu, Mario Chemnitz +15 more

Time-entanglement is a promising resource for the implementation of quantum communications over standard fiber networks. In particular, photonic qudits can enhance the performance of quantum communication, including quantum key distribution, in terms of noise robustness, quantum information content, distance reach, as well as security and secret key rates. However, time-entangled photonic qudits are not ready yet to be fully exploited for quantum communications in fiber networks that are fully compatible with standard telecommunication architecture. Here, we demonstrate the implementation of telecommunication-compatible quantum communications based on picosecond-spaced time-entangled qudits. To this end, we make use of an integrated photonic chip comprising a cascade of programmable interferometers and a spiral waveguide. We use entangled qudits to implement high-speed quantum key distribution, chip-to-chip entanglement distribution, and quantum state propagation over 60 km of standard fiber. Our results show the potential of time-entangled qudits for high-speed quantum communications in telecommunication-compatible architecture.

Stefania Sciara, Hao Yu, Mario Chemnitz +20 more

Encoding quantum information into time-bin entangled photons offers a physics-rich framework for both fundamental and applied quantum science. Here, we present two frameworks enabling the generation and manipulation of time-bin entangled photonic qudits for both fundamental and applied quantum information processing. The first framework consists of a scalable synthetic temporal photonic lattice implemented on a coupled fiber-loop system that is employed to explore and dynamically control the evolution of the discrete-time quantum walk of time-bin entangled photon states. The other framework consists of a modular, fiber-pigtailed, integrated photonic platform enabling the generation and processing of time-bin entangled qudits that were used to demonstrate the first Bennett-Brassard-Mermin 1992 QKD protocol extended to qudits. We operate the entangled qudits at processing speeds typical of standard telecommunication systems at 10s of GBaud.

Marek Sawerwain, Joanna Wiśniewska