Professor Alexander Kubanek, University Ulm, Germany 
Leuchs-Russell Auditorium, A.1.500, Staudtstr. 2
Location details

Abstract: 
Implementing efficient, highly controllable light-matter interfaces is essential to realizing goals such as solid-state quantum networks. Color center in diamond and, in particular, the negatively charged silicon-vacancy (SiV-) center are promising candidates for such interfaces due to favorable optical properties and long coherence times at low temperatures. Creating optical links between remote SiV- centers via photon-mediated spin-spin entanglement is an outstanding challenge. An efficient link could be realized by Purcell-enhanced optical transitions by means of optical resonators. The integration into the mode of an optical resonator is demanding and requires, e.g., absence of scattering and nanometer precision. Therefore, small dimensions of the host matrix are favorable. However, the resulting proximity of the quantum emitter to the surface typically degrades optical and coherence properties.

In this talk I will focus on our work on how to obtain single SiV- centers per one nanodiamond with ideal optical properties. I will introduce our path to integrated, hybrid, quantum devices by post-processing classical photonic and plasmonic structures with color centers in nanodiamonds. I will analyze the achieved coupling efficiency resulting in simulated Purcell-factors beyond 500 and measured Purcell-enhancement of more than 4.

Furthermore, I will briefly talk about the integration of diamond membranes into fiber-based optical resonators without affecting the properties of the empty cavity. We used the coupled system, for example, to extract the absorption cross section of SiV-centers. 

If time permits, I will discuss our recent and very exceptional discovery of Fourier- Transform limited lines from defect centers in hexagonal Boron Nitride (hBN) at room temperature.

References 

[1] S. Häußler et. al., Phys. Rev. B 99, 165310 (2019) 

[2] L. J. Rogers, et al., Phys. Rev. Applied 11, 024073 (2019)

[3] K. G. Fehler, et al., ACS Nano 13, 6891−6898 (2019) 

[4] S. Häußler, et al., New Journal of Physics, in press (2019)

[5] K. G. Fehler, et al., Nature Light: Science & Applications, under review (2019)

[6] H. Siampour, et al., arXiv:1903.05446 (2019)

[7] T. T. Tran, et al., ACS Photonics 5 (2), pp 295–300 (2018)

[8] A. Dietrich, et al., Physical Review B, vol. 98, no.081414(R) (2018)

[9] A. Dietrich, et al., arXiv:1903.02931 (2019)