Harnessing Halides to Transform Colloidal Nanocrystals into High-fidelity Quantum Light Sources

Bowling Green State University, Bowling Green OH

Investigators

Abstract

With the support of the Macromolecular, Supramolecular and Nanochemistry (MSN) Program in the Division of Chemistry, Professor Mikhail Zamkov of Bowling Green State University will explore a new chemical method for improving the optical performance of small semiconductor nanoparticles, known as colloidal nanocrystals. These materials could serve as the foundation for future quantum technologies, including secure communication networks, quantum-enhanced sensors, and advanced computing systems. Presently, the practical use of colloidal nanocrystals in such applications is hampered by inherent defects in their crystal structure that lead to unpredictable optical flickering and color changes, making nanocrystals unreliable for demanding quantum applications. This project will address this issue by developing a halide-based chemical treatment to “repair” imperfections in the nanocrystal lattices. By restoring the structural order, this method is expected to reduce the noise in the emitted light and enable a stable production of single or paired photons, which represent an essential requirement for any quantum information system. The research will also focus on theoretical modeling to understand how halide ions interact with atomic-scale defects. In addition to its scientific goals, the project will contribute to workforce development by ensuring the undergraduate student participation in hands-on research and hosting outreach activities in chemical sciences. Potential collaborations with industry may further extend the impact of this work. This project will develop a halide-mediated defect treatment strategy for colloidal semiconductor nanocrystals, aiming to stabilize their optical emission for use in quantum photonic applications. In contrast to traditional surface treatments, the proposed method will leverage eutectic-phase interactions between halide salts and semiconductor nanocrystals to induce a partial lattice reorganization, eliminating stacking faults and neutralizing charge-trapping surface states. By tuning the reaction conditions, the treatment is expected to suppress photoluminescence intermittency and spectral diffusion, which are presently identified as the two major obstacles limiting the performance of colloidal quantum emitters. This research will systematically evaluate the efficiency of such halide treatment across multiple II–VI and III–V nanocrystal systems and explore its role in enabling correlated photon pair emission from single nanoparticles. Complementary theoretical modeling will provide atomistic insights into halide-defect interactions, guiding experimental efforts. Ultimately, this work could result in the demonstration of scalable quantum light sources that lower the cost and increase the accessibility of quantum technologies. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.