Mechanically isolated quantum emitter in hexagonal Boron Nitride - Alexander Kubanek

Single photon sources are among the most crucial constituents of photonic quantum technology. Solid-state based quantum emitters are of particular importance since they offer robust and scalable platform development with potential applications in quantum information and quantum sensing. All solid-state emitters have in common, that they interact strongly with the thermal bath and lattice phonons reducing the optical and spin coherence. Therefore, solid-state quantum optics experiments are restricted to operate at cryogenic temperatures in order to suppress interactions with the solid-state environment. A measure for the optical coherence is the linewidth of an optical transition. Perfect coherence is achieved when all incoherent processes arising from interactions with the environment are suppressed. Once suppressed, the spectral line of a single photon emitter matches the Fourier Transform of its excited state decay.
In this talk I will discuss our recent investigations on defect center in hexagonal Boron Nitride. We studied more than 1000 defect centers with emission frequencies across almost the complete visible spectrum. For some of these emitters, we have observed Fourier-Transform limited lines at cryogenic temperatures under resonant excitation. We interpret our findings with the absence of any dephasing mechanism on the timescale of the scan. Surprisingly, we have discovered that these narrow optical transitions persist when increasing the temperature up to ambient conditions. Such behavior could be explained by a defect center that is decoupled from in-plane phonon modes which, in turn, could be explained by an out-of-plane defect center. I will introduce the audience to our model and understanding of the underlying physics. Furthermore, I will define characteristic features on how to identify these remarkable emitters among others. References
[1] A. Dietrich, et al., Physical Review B, vol. 98, no.081414(R) (2018)
[2] A. Dietrich, et al., Physical Review B 101, 081401(R) (2020)
[3] M. Hoese, et al., Science Advances 6, eaba6038 (2020)
[4] S. Häußler, et al., arXiv:2006.13048 (2020)
[5] M. Hoese, et al., arXiv:2102.09357 (2021)