Upcoming Talks

High-dimensional entanglement is the fundamental basis for large-scale, controllable, and useful quantum systems. The most promising entanglement platforms are consequently extensively examined for computation, communication, and sensing networks, including superconducting qubits, trapped ions, color centers, Silicon gates, and photons. With unique advantages and challenges of each platform, entangled photonic quantum states at room temperature are of particular interest in networks because they can be transmitted over long distances with preserved non-local coherence while providing an effective route for interaction with other qubit modalities and hybrid systems. My research focuses on the generation, control, and distribution of large-scale high-dimensional entangled photonic systems. In these systems with large Hilbert space dimensionalities across all degrees of freedom, there are two main challenges. First, certification of the accessible entanglement and its metrology such as state tomography with feasible measurement times and resources has been a long-standing core challenge in the quantum science and engineering community. The second challenge is that the current operating speed of the quantum network is still at the level of a few dozen/hundreds of bits. To address the first challenge, I recently demonstrated the certification of an entanglement Hilbert space up to 648 dimensions through Schmidt mode decomposition and the entanglement-of-formation to lower-bound the communication ebits between parties, the baseline unit of bipartite entanglement. Recently, we provided a comprehensive review of high-dimensional entanglement of quantum frequency combs, which highlights the potential and possibility of large-scale time- and frequency-multiplexing using these specialized multimode qudit sources. In parallel, I advanced ultrabright d-dimensional entanglement sources, with implementation in quantum communication channels and robust multi-user networks. This includes a quantum network testbed at UCLA, with efficient error correction, multi-qubit-per-photon communications, and loss-tolerant protocols. Each of these has been published in leading-edge Nature and Quantum science and engineering journals of impact, contributing to the advances in high-dimensional entanglement for large-scale quantum computation, and communication networks.

Dr. Kai-Chi Chang obtained his B.S. from National Central University, and M.S. in Electrophysics from National Chiao Tung University, both from Taiwan in 2014 and 2016, and obtained his PH.D. in Electrical Computer and Engineering at UCLA in 2022. During his PH.D., he has published three high-ranking journal articles, including npj Quantum Information and Optics Express, and 15 top conference papers, including CLEO and APS. He was a UCLA PH.D. Dissertation Research Award Finalist, and has obtained UCLA Dissertation Year Fellowship, J. Yang Scholarship, Electrical and Computer Engineering Department Fellowship, and Ministry of Education Fellowship from Taiwan. In his postdoctoral research study, he further advanced the field of high-dimensional quantum information processing and quantum communication, chip-scale quantum computing, and nonlinear quantum photonics by establishing 19 manuscripts, with publications in top quantum physics and photonics journals (such as Newton, Nature Photonics, Photonics Research, Communications Physics, Quantum Science and Technology, and APL Quantum), together with 38 conferences papers in CLEO and APS, and one patent. He was a UCLA Chancellor Award for Postdoctoral Research Finalist. He also serves as a Guest Associate Editor in special collections of Quantum Optics in Frontier in Photonics, and peer-reviewed scientific journals npj Quantum Information, Physical Review Letters, npj 2D Materials and Applications, Laser Photonics and Reviews, Quantum Science and Technology, Optics Letters, Optics Express, Chinese Journal of Physics, Journal of Lightwave Technology, Review of Scientific Instruments, Frontier in Physics, Physica Scripta, Optical and Quantum Electronics, Optics Communications, and IEEE Photonics Journal.