Kolloquium  /  January 18, 2021, 17.15 Uhr

Kolloquium zur Halbleitertechnologie und Messtechnik: Quantentechnologie mit Farbzentren in Wide-Bandgap-Halbleitern

18. Januar 2021, 17:15 Uhr, online

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Quantum communication with color defects in 4H-SiC

Prof. Dr. Roland Nagy, Fraunhofer IISB

Optically interfaced spins in the solid promise scalable quantum networks. Robust and reliable optical properties have so far been restricted to systems with inversion symmetry. Here, I release this stringent constraint by demonstrating outstanding optical and spin properties of single silicon vacancy centers in silicon carbide. Despite the lack of inversion symmetry, the system's particular wave function symmetry decouples its optical properties from magnetic and electric fields, as well as from local strain. This provides a high-fidelity spin-to-photon interface with exceptionally stable and narrow optical transitions, low inhomogeneous broadening, and a large fraction of resonantly emitted photons. Further, the weak spin-phonon coupling results in electron spin coherence times comparable with nitrogen-vacancy centres in diamond. This allows us to demonstrate coherent hyperfine coupling to single nuclear spins, which can be exploited as qubit memories. This finding promises quantum network applications using integrated semiconductor-based spin-to-photon interfaces.

Functionalized single atoms for sensing and quantum information technology engineered by ion beam implantation
Prof. Dr. Jan Meijer, Felix-Bloch-Institut, Universität Leipzig

The challenge of the ultimate nanotechnology engineering is the ability to prepare single atoms as full functional devices. Especially the nitrogen-vacancy (NV)-center in diamond and V in SiC plays an increasing role in these fields, taking advantage of some recent technological breakthroughs and of the remarkable overall physical properties like a coherent spin control even at room temperature. The color centers are already used as single-photon sources or single molecule NMR magnetometer and became a promising candidate for quantum computing at room temperature. However, all these applications require the ability to create scalable arrays with high lateral resolution. The talk will give an overview about the status quo of applications using color centers, the properties of a new color center found in Leipzig and will show new prospects in addressing of countable single atoms by ion beam implantation.