Dresden 2017 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 69: Quantum Dots: Transport Properties I

HL 69.4: Talk

Thursday, March 23, 2017, 10:15–10:30, POT 151

Reflectometry readout of Ge hole spin qubits — •Josip Kukučka, Lada Vukušić, Hannes Watzinger, Elisabeth Lausecker, and Georgios Katsaros — IST Austria

Group IV materials and in particular Si have attracted much interest for the realization of a spin qubit especially since coherence times of almost one second were reported for an electron spin in isotopically purified samples [1]. In our group we are working with hole spin qubits confined in quantum dots formed in Ge hut wires. Due to the recently shown almost purely heavy-hole character of the confined hole states [2], not only long dephasing times but also fast spin manipulation times are expected for this type of hole spin qubit. In order to measure dephasing times, a series of spin-dynamic experiments are going to be performed. Fast qubit state readout is required for these experiments. We have implemented and optimized radio-frequency ohmic reflectometry [3]. The influence of the printed circuit board layout and resonance circuit elements on the sensitivity of the measurements will be addressed. In order to further simplify the sample fabrication and readout protocol, we are currently developing gate reflectometry [4,5], which will use already defined gates that are needed for the electrostatic definition of a double quantum dot system. First results will be presented. [1] Muhonen, J. T et al. Nature Nanotechnology 9, 986 (2014) [2] Watzinger, H. et al. Nano Lett. 16, 6879*6885 (2016) [3] Ares, N. et al. Phys. Rev. Applied 5, 034011 (2016) [4] Colless, J. I. et al. Phys. Rev. Lett. 110, 046805 (2013) [5] Gonzalez-Zalba, M. F. et al. Nature Communications 6, 6084 (2015)