Institutskolloquium: Trapped ion quantum computing and single ion implantation for novel quantum technologies

Prof. Ferdinand Schmidt-Kaler, Uni Mainz

Quantum technologies allow for fully novel schemes of computing, simulation and sensing. For quantum computing, we employ trapped ions in modern segmented ion traps as scalable and freely reconfigurable qubit register [1]. I will give an overview of the recent progress, where gate fidelities of 99.995% (single bit) and 99.6% (two bit) are reached. At the moment, we start realizing quantum error correction algorithms [2] which would be able to extend the coherence of qubits. Alternative platforms for quantum computers in solid state technology would largely benefit from deterministic schemes to fabricate qubit registers with nm-accuracy. I describe our deterministic ion source, which allows for delivering Ca+ ions on demand and focus it into a spot of a few nm [3]. The source can be operated with any other doping ion, which is co-trapped and sympathetically cooled together with a single Ca+ ion, eventually extracted and implanted. We have started structuring solid state samples such as diamond with N2+ molecular ions to generate NV centers, and implanting rate-earth Presodym single ions on demand and reached a positioning accuracy of 35nm inside a Yttrium Aluminum Garnet crystal [4].

[1] Kaufmann er al, Phys. Rev. Lett.  119, 150503 (2017)
[2] A. Bermudez et al, Phys. Rev. X 7, 041061 (2018)
[3] Jacob et  al, Phys. Rev. Lett. 117, 043001 (2016)
[4] Groot-B. et al, Phys. Rev. 123, 106802 (2019)

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