Nonlinear Optical Two-Dimensional Perovskite Light Sources for Quantum Technologies

With support from the Chemical Structure and Dynamics (CSD) program in the Chemistry Section, Professor Andrew Moran at the University of North Carolina at Chapel Hill is exploring the use of two-dimensional organic-inorganic hybrid perovskite quantum wells as light sources with adaptable polarization states for quantum information technologies. Emerging quantum communication systems will require light sources whose properties can be precisely controlled, yet many existing approaches rely on external optical components to manipulate light after it is generated. Professor Moran and his students will investigate whether the internal physical behavior of perovskite quantum wells, particularly the way electronic spins evolve on very short timescales, can be used to control the properties of the emitted photons within the material itself. This approach could enable the development of new light sources suitable for secure communication and other quantum technologies. Their studies will advance understanding of how ultrafast material dynamics influence the quantum properties of light and will help clarify how perovskite materials could function as practical quantum light sources. The project will also contribute to education and outreach through training of students in interdisciplinary research and the development of public engagement tools that introduce quantum communication concepts to broader audiences. This project uses nonlinear optical spectroscopies to investigate how spin dynamics and many-body interactions in two-dimensional organic-inorganic hybrid perovskites shape the properties of emitted photons. Four-wave-mixing techniques are employed, in which the polarization ellipticity of the signal field serves as a sensitive probe of ultrafast spin relaxation processes within the exciton fine structure. By analyzing how these signal polarization states evolve as a function of time and experimental conditions, the research will establish quantitative links between microscopic material dynamics and the resulting photon properties. Particular attention will be given to biexciton resonances, which radiate photons with distinct polarization ellipses and have been shown to enhance the efficiency of polarization-encoded quantum communication. The project will also employ multidimensional spectroscopies to characterize correlations in energy level fluctuations and to distinguish homogeneous and inhomogeneous broadening mechanisms that influence photon coherence. These measurements will inform the design of quantum communication protocols in which four-wave-mixing signal photons are used to transmit ASCII messages via material-intrinsic encoding. Educational impacts will include the development of a simplified, hands-on version of the BB84 quantum key distribution protocol designed for use in high school and undergraduate learning environments. 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.