Photon Correlations from MAGnetIcally Doped Quantum Dots (Photon-MagiQ)

• Applicant: Professorin Dr. Doris Reiter
• Subject Area: Theoretical Condensed Matter Physics ; Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 577681036

Semiconductor quantum dots are among the most advanced solid-state quantum emitters, as they combine high yield with excellent photon-quality. A promising approach to extend their capabilities is doping them with single magnetic ions. Through strong exchange interactions, the magnetic ions shape the electronic and optical structure of the quantum dots and give rise to complex spin-photon interactions. This opens up novel functionalities: on the one hand, magnetically doped quantum dots provide a natural spin-photon interface, on the other hand, they offer the possibility to generate spectrally distinguishable, spin-entangled photons as well as potentially strongly correlated multi-photon states. Despite these intriguing properties, magnetically doped quantum dots have so far hardly been investigated systematically in the context of quantum photonics. Until the mid-2000s, quantum dots containing only a single magnetic ion were regarded as exotic systems, but in recent years more of such systems have been realized. At the same time, realistic theoretical modelling of the large Hilbert spaces with spin–photon coupling was long out of reach. With modern open-quantum-system frameworks (e.g. tensor-network methods such as ACE or the simulation package QuTiP) and advanced methods for calculating time-resolved multi-time correlation functions, it has now become possible for the first time to quantitatively describe the photon dynamics of such systems under physically realistic conditions. The proposed project Photon-MagiQ builds precisely on this progress. Its goal is to systematically investigate the spin–photon dynamics in magnetically doped quantum dots and to realistically assess the potential of these systems for quantum photonics. The central questions are: (i) Can magnetically doped quantum dots provide a genuine advantage for quantum photonics compared to undoped emitters? (ii) What are the physical mechanisms underlying the changes in photon correlations, entanglement, and emission quality induced by the magnetic ions? (iii) Can quantitative theoretical benchmarks be derived that are robust enough to serve as a basis for future experiments? The expected outcome of the project is a quantitative, theoretically founded framework that clearly shows the opportunities and limitations of magnetically doped quantum dots for quantum photonics. In this way, a new path towards the generation of structured, entangled photon sources in the solid state might be opened. Thus, Photon-MagiQ will make a fundamental contribution to the understanding of complex light–matter interactions and to the advancement of quantum photonics.

• DFG Programme: Research Grants