Spin Noise Spectroscopy and Resonance Fluorescence on Noisy Nanosystems

• Applicant: Professor Dr. Michael Oestreich
• Subject Area: Experimental Condensed Matter Physics
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 559570045

Noise as intrinsic fluctuations of measurable physical quantities is a fundamental property that influences many processes in the solid state. Particularly, the noise in semiconductors typically results either from the fluctuation of charge or from the fluctuation of spins or a rather complicated combination of both. Especially in low-dimensional semiconductors, a fundamental understanding and possible control of this noise is of current interest, for example, in the context of stochastic quantum coherence, quantum dot quantum sensing, and entanglement of Fourier transform-limited single photon sources. A particularly suitable method for investigating these noise dynamics in semiconductor nanostructures is optical spin noise spectroscopy, which sensitivity has been increased since 2005 to such an extent that it is now possible to measure individual charge carriers. However, the experiments show that the traditional spin noise spectroscopy used to date has reached its limits with complex nanosystems despite excellent optimization. In this proposal, we will reach beyond the limits of traditional spin noise spectroscopy and develop the technique towards single-photon spin noise spectroscopy and at the same time combine it with single-photon resonance fluorescence to create a new, versatile basic measurement technology. We will demonstrate single-photon spin-noise spectroscopy with extremely high time-resolution and push the sensitivity to the quantum mechanical limit using factorial cumulants and single-photon polyspectra. We will also investigate the manifold coupled charge and nuclear spin dynamics, test the current theories on spin-noise spectroscopy, investigate quantum mechanical photon-spin interactions, explore the fundamentals of spin and carrier dynamics with respect to spin-photon interfaces, and observe and manipulate the noise coupling of semiconductor quantum dots.

• DFG Programme: Research Grants
• Major Instrumentation: 15 Watt, 532 nm Pumplaser
• Instrumentation Group: 5700 Festkörper-Laser