Jehyung Kim

Affiliation: Ulsan National Institute of Science & Technology (UNIST)

Research Interests: Quantum photonics

Title: How Imperfections Make Quantum Materials and Quantum Devices Better
Abstract: Solid-state quantum emitters have attracted much attention as an integrated source of photonic and spin qubits, which are basic elements for a range of quantum applications. Recent advances in the generation, manipulation, and integration of these emitters demonstrate a variety of quantum resources: bright quantum light sources, quantum memories, and spin-photon interfaces. However, such qubits in solid-state environments suffer from various unwanted interactions with phonons and charges, resulting in broad spectrum and decoherence. Additionally, the high refractive index of hosting medium limits light extraction and coupling and thus prevents efficient control and readout of quantum emitters. Therefore, researchers have sought to create faultless systems by improving the qualities of quantum materials and photonic devices. However, these efforts to eliminate imperfections mostly require rigorous experimental conditions and sophisticated techniques, making the system less practical and scalable.
In this talk, I will present recent approaches that leverage the benefits of crystal defects and low-Q cavities, and show that imperfections can actually help address challenges in quantum materials and devices.. In the first part I will discuss how 2D stacking faults can efficiently decouple electron-phonon interactions for a single point defects, leading to unexpected strong zero-phonon transition. In the second part, I will introduce cavity-mediated collective interaction, highlighting the role of cavity dissipation loss. In this system, we observed the formation of steady-state subradiant state for the first time, leading to long-lived quantum correlation between multiple emitters.
Our distinctive approaches could provide valuable quantum resources in a more efficient and practical manner, while also offering new insights into fundamental quantum light-matter interactions.