Berlin 2024 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 13: Poster I

HL 13.59: Poster

Monday, March 18, 2024, 15:00–18:00, Poster E

Strongly driven germanium quantum dot — •Bashab Dey and John Schliemann — University of Regensburg, Regensburg, Germany

Hole qubits in germanium quantum dots are promising candidates for coherent control and manipulation of the spin degree of freedom. The suppression of contact hyperfine interaction due to p-character of the holes, isotopic purification and absence of valley degeneracies are favourable for sustaining longer spin coherence and relaxation times in these systems. Furthermore, stronger spin-orbit interaction in germanium hole states facilitates faster qubit operations in these dots as compared to silicon or III-V semiconductors. Quantum NOT gates can be realized using these qubits through electric dipole spin resonance (EDSR) where Rabi oscillations are induced between the spin-up and -down states using ac-gate voltages. In this work, we theoretically study the time dynamics of a single hole qubit in a laser-driven planar germanium quantum dot confined laterally by a parabolic potential in presence of Rashba spin-orbit coupling(s) and a perpendicular magnetic field. We employ different methods such as Floquet theory and unitary transformations to study the time evolution of the qubit under the laser field. We obtain approximate analytical formula for the Rabi oscillations using a Schrieffer-Wolff transformation and establish a connection of our model with the ESDR results obtained for this system.

Keywords: Electric dipole spin resonance; Germanium quantum dot; Hole qubit; Floquet theory