2020/11/30 by Daniel Jirovec, Andrea Hofmann, Andrea Ballabio +14 · 4 citations
Physics and Astronomy · #Coherence (philosophical gambling strategy) #Coherence time #Dephasing #Mechanical and Optical Resonators #Physics of Superconductivity and Magnetism #Planar #Quantum and electron transport phenomena #Quantum computer #Qubit #Spin (aerodynamics) #Spin engineering #Superconducting quantum computing #cond-mat.mes-hall #quant-ph
paper · pdf · doi:10.1038/s41563-021-01022-2
openalex created_date 2020/12/07 · arxiv created 2021/04/07 · openalex publication_date 2021/06/03 · arxiv updated 2021/06/07 · openalex updated_date 2026/08/05
Spin qubits are considered to be among the most promising candidates for building a quantum processor. GroupIV hole spin qubits have moved into the focus of interest due to the ease of operation and compatibility with Si technology. In addition, Ge offers the option for monolithic superconductor-semiconductor integration. Here we demonstrate a hole spin qubit operating at fields below 10 mT, the critical field of Al, by exploiting the large out-of-plane hole g-factors in planar Ge and by encoding the qubit into the singlet-triplet states of a double quantum dot. We observe electrically controlled g-factor-difference-driven and exchange-driven rotations with tunable frequencies exceeding 100 MHz and dephasing times of 1 μs which we extend beyond 150 μs with echo techniques. These results demonstrate that Ge hole singlet-triplet qubits are competing with state-of-the art GaAs and Si singlet-triplet qubits. In addition, their rotation frequencies and coherence are on par with Ge single spin qubits, but they can be operated at much lower fields underlining their potential for on chip integration with superconducting technologies.