High-fidelity single and two-qubit gates in germanium*

The promise of quantum computation with quantum dots inspired over two decades of intensive research on creating and manipulating single spins in semiconductor structures. The main focus was initially on GaAs, because of device maturity, and later on silicon, that can be isotopically purified to support extremely long quantum coherence times. Here, I will present germanium as a material that can combine these assets to form an excellent quantum material [1]. I will present the first planar germanium quantum dots, hosting single holes. I will show excellent quantum dot behavior with great control [2]. Single qubits can be defined on these holes with fidelities over 99% and can be coupled to execute two-qubit logic gates. Interestingly, these systems can also make contact to superconductors. I will present our latest efforst on hybrid structures, including micro meter long supercurrents and supercurrent discretization [2,3]. Germanium bears therefore great promise for fast and coherent quantum hardware.

[1] Sammak et al. arXiv:1809.02365
[2] Hendrickx et al. Nature Communications 9, 2835 (2018)
[3] Hendrickx et al. arXiv:1808.00763