SKM 2023 – scientific programme
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O: Fachverband Oberflächenphysik
O 15: Spins on Surfaces at the Atomic Scale II
O 15.7: Talk
Monday, March 27, 2023, 16:30–16:45, REC C 213
Surface spins as quantum bits - a simulation perspective — Jose Reina Gálvez1, Nicolas Lorente2, and •Christoph Wolf1 — 1Center for Quantum Nanoscience, Institute for Basic Science, Seoul, South Korea — 2Materials Physics Center, San Sebastian, Spain
Spins localized at or close to a clean surface have emerged as systems of interest in quantum nanoscience. They can be tailored to a desired spin state, manipulated to form structures with designed interactions and as of recent have been used to implement basic quantum logic operations - a control-NOT gate - in a scanning tunneling microscope (STM). In this work we want to explore quantum coherent phenomena of surface spins from a computational perspective. Since surface spins interact rather strongly with the environment, we performed open quantum systems calculations. First, we will show how electron-electron double resonance can be understood by solving the time-dependent Schrodinger equation under continuous and pulsed radio-frequency driving. Using the same prototypical system of two coupled electron spins we also show how the AC Stark effect manifests itself as Autler-Townes doublets and Mollow triplets. To go one step further, we use our recently developed approach to explicitly calculate the current present in the STM experiment using the non-equilibrium Green's functions formalism. These simulations show how the current plays a dual role in these systems by driving quantum transitions but also limiting quantum coherence. Our simulations outline realistic expectations for quantum coherent surface spin systems and their prospective applications.