Multiplexing of nonlinear single photon pair generation based on thin-film lithium niobate photonics platform

Yunhong Ding

Department of Electrical and Photonics Engineering

Technical University of Denmark

Abstract: Quantum photonics is emerging as a prominent candidate for the development and implementation of quantum technologies, manifesting its capabilities in demonstrating a quantum computational advantage, and ensuring error protection. However, in order to fully harness the potential of quantum technologies beyond proof-of-principle experiments, periodic and near-deterministic single-photon sources are required. Heralded photon sources, crucial in many quantum photonics investigations, generate a pair of single photons (signal and idler) through the virtual absorption of two pump photons, utilizing nonlinear optical processes, such as spontaneous four-wave mixing (SFWM). However, their performance is constrained by the limited probability of generating a photon pair to avoid unwanted multiple-photon-pair generation. This limitation impedes the scalability, making them unsuitable for more complex architectures. To address this challenge, a technique called multiplexing of probabilistic sources was proposed. The basic idea is to use a number of photon pair sources and exploit heralding (detection of idler photon) for routing the heralded photon (signal) to a single mode output. Multiplexing can utilize various orthogonal degrees of freedom, including temporal, spatial or their combinations. Temporal multiplexing schemes, which require only a single photon detector, an actively controllable storage medium, and a photon pair source, offer a significant advantage over spatial multiplexing schemes in terms of physical resources. Previous demonstrations of temporal multiplexing in fiber-based systems have been reported with effective enhancements of the single photon generation probability. However, the scalability is limited by discrete components. In this work, we present the first temporal multiplexing scheme on-chip, based on high-speed and low-loss thin film lithium niobate (TFLN) photonics device. We have demonstrated single photon storage on-chip, and effective temporal multiplexing of single photon pairs, showing excellent scalability and potential for future near-deterministic nonlinear single photon generation.

Biography: Prof. Yunhong Ding obtained his Ph.D. at the Huazhong University of Science and Technology, Wuhan, China, in 2011. Afterwards, he joined the Department of Electrical and Photonics Engineering (DTU Electro), and has been the PI or Co-PI of H.C. Ørsteds Grant, DFF FTP Grant, Sapere Aude Forskertalent, and EU QuantERA Project. Since 2017, he has been an Associate Professor/Senior Researcher at DTU Electro, and was granted the Villum Young Investigator in 2019. In 2018, Dr. Ding founded a foundry SiPhotonIC ApS which provides services of design and fabrication of photonic integrated circuits on silicon photonics platform. Dr. Ding research activities are focused on integrated quantum photonics based on silicon photonics and thin-film lithium niobate photonics platforms. Dr. Ding has published more than 80 peer reviewed papers, including Science, Nature Photonics, Nature Physics, Nature Communications, Nano Letters etc.