Cavity-mediated quantum correlation between QDs
Kyu Young Kim, Jinhee Lee, Woong Bae Jeon, Dong Hyun Park, Suk In Park, Jin Dong Song, Changhyoup Lee, Je‐Hyung Kim · 2025
Cooperative phenomena, such as super(sub)radiance in quantum systems, arise from interactions among quantum emitters. Superradiance has been intensively studied from various platforms. While superradiance provides a good insight into the collective effect in quantum systems, exploiting the entangled state is not easy because of its strong radiative nature. In contrast, subradiance remains largely unexplored due to its inherent dark nature, despite its long lifetime and robustness against dephasing. Here, we experimentally demonstrate a long-lived subradiance among multiple quantum dots coupled to a low-Q cavity. The directional cavity mode provides a constant momentum condition, similar to a waveguide, and facilitates a shared radiative field among the quantum dots. By balancing cavity dissipation, incoherent pumping, and coupling strength, we realize steady-state subradiance rather than superradiance. As a key signature of subradiance, we observe a stark change in the photon statistics, with photon bunching exceeding the classical limit of 2. Additionally, we engineer the coupled system by changing detuning and incoherent pumping. Furthermore, modifying the pumping mechanism allows us to manipulate the dephasing of quantum dots involved in the cooperative process. Our experimental study on cavity-mediated cooperative phenomena among multiple quantum dots introduces a novel approach to generating quantum correlations with long-lived entanglement, offering potential applications in quantum storage and metrology.