International Conference on Quantum Physics of Nature (QuPoN 2015) Mitschnitt einer Veranstaltung der Fakultät für Physik am Dienstag, dem 19. Mai 2015 im Großen Festsaal der Universität Wien Teil 19. Kathrin Buczak: "Creation and charge state dynamics of NV centres for quantum applications" Schnitt: Daniel Winkler Abstract: In the past decades the negative nitrogen-vacancy (NV-) centre in diamond has demonstrated its versatility both as a sensor for temperature, electrical and magnetic fields, and as a promising solid-state system for quantum information processing. The negative charge state is photochemically not stable and loses the essential properties for the mentioned applications as soon as it converts to the neutral charge state, NV0. Thus, the charge state conversion dynamics of the NV centre play a key role in the understanding and application of the color centre. We show measurements of the charge state dynamics for NV centre ensembles close to the surface of an artificial diamond. We implanted 1010 – 1013/cm² nitrogen ions 14N4+ (8 keV) into a CVD diamond with initially < 100 ppb nitrogen content. As a result we created 25 different NV centre densities within a thin layer, just 12nm below the diamond surface. Through two-color laser excitation pulse sequences we have explored the time dependence of ionization (NV- → NV0) and recombination (NV0 → NV-). This allowed us to measure laser-induced conversion processes. In the course of this study, we discovered that charge conversion also takes place spontaneously and the characteristics of the decay (NV- → NV0) depend strongly on the density of the color centres. The characterization of these processes is of importance for numerous applications of NV centres, including sensing of charges and fields near the surface of the diamond, as the decay process limits the coherence time – and thus the sensitivity – of NV-based sensors. Deterministic placement of NV centres is essential for their use in photonic and electrical structures. We are now exploring the potential of masked implantation via electron-beam lithography and subsequent nitrogen implantation to create arrays of implanted NV defects. Fine-tuning the initial mask resist parameters and the implantation fluence has enabled us to scale NV creation down to single NV centres. The nanometer-scale accuracy of this process, combined with the fabrication of electrical and microwave structures on the diamond surface, will allow the creation of large-scale arrays of sensors and quantum devices. Kathrin Buczak ist Doktorandin am Atominstitut der Technischen Universität Wien. INHALT ====== Kapitel Titel Position --------------------------------------------------------------------- 1. Vorspann 00:00:00 2. Motivation 00:00:12 3. Optically detected magnetic resonance (ODMR) 00:04:00 4. Charge state switch mechanism 00:06:58 5. Masked implantation 00:11:14

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