Berlin 2024 – scientific programme

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QI: Fachverband Quanteninformation

QI 28: Surface Atom and Color Center Spin Qubits

QI 28.8: Talk

Thursday, March 21, 2024, 17:15–17:30, HFT-FT 131

Coherence properties of NV-center ensembles coupled to an electron-spin bath in diamond — Reyhaneh Ghassemizadeh, Wolfgang Körner, •Daniel F. Urban, and Christian Elsässer — Fraunhofer Institute for Mechanics of Materials IWM, Freiburg, Germany

Nitrogen-vacancy (NV) centers in diamond are one of the promising solid-state-based qubit platforms. Quantum-technology applications in general require long coherence times for the qubit. However, the coherence time of NV centers is limited due to their coupling to the surrounding fluctuating environmental electronic and nuclear spins. In this study we use the cluster-correlation expansion (CCE) method to study the decoherence of ensembles of NV centers in a range of electron-spin bath-concentrations ρ of 0.1 - 100 ppm. We demonstrate the statistical ensemble averaging and compute the Hahn-echo coherence time (T₂) and the stretched exponential parameter as a function of ρ. Moreover, we perform a geometrical analysis in order to determine the effective dipolar interaction length depending on the bath concentrations. Our results provide a quantified description of the decoherence behaviour of NV ensembles as well as individual electron-spin bath-configurations that lead to a prolonged coherency of the NV center.

Keywords: NV Center; Coherence Time; Quantum Computing; Quantum Magnetometry; Cluster-Correlation Expansion (CCE)