Freiburg 2019 – wissenschaftliches Programm

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FM: Fall Meeting

FM 40: Poster: Quantum Computation: Hardware Platforms

FM 40.3: Poster

Dienstag, 24. September 2019, 16:30–18:30, Tents

A spin qubit in ²⁸Si/SiGe with 60 ppm ²⁹Si — •Floyd Schauer¹, Tom Struck², Arne Hollmann², Andreas Schmidbauer¹, Carlo Peiffer¹, Veit Langrock², Helge Riemann³, Nikolay V. Abrosimov³, Lars R. Schreiber², and Dominique Bougeard¹ — ¹Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Regensburg, Germany — ²JARA-FIT Institute Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany — ³Leibniz-Institut für Kristallzüchtung, Berlin, Germany

²⁸Si is a strong candidate for hosting spin qubits, promising long qubit coherence times in a technologically scalable environment. Electrostatically-defined quantum dots in ²⁸Si/SiGe heterostructures have been proven to robustly allow the implementation of spin qubits, as long as their device-inherent valley splitting energy is sufficiently large to operate the qubit.

Here, we present the characterization of a gate-defined single spin qubit in a quantum dot layout with an integrated nanomagnet. The qubit is hosted in a molecular-beam epitaxy-grown ²⁸Si/SiGe heterostructure presenting only 60 ppm residual ²⁹Si. We determine the relevant single electron quantum dot energies, finding a robust valley splitting beyond 200 µeV and a well separated orbital energy beyond 1 meV. Below the valley splitting energy, we observe spin relaxation times T₁>1 s which are independent of the externally applied magnetic field. Using electron dipole spin resonance, the manipulation of the qubit yields T₂^* ∼ 22 µs and long T₂^echo ∼ 127 µs.