The germanium quantum information route

The semiconductor industry knows how to make and integrate billions of excellent transistors. What are the materials requirement that will enable the integration of excellent qubits for the quantum information age of tomorrow? I will make a case for the germanium quantum information route[1] as we are moving into the next phase of engineering qubit systems in the large numbers required for useful quantum computing. Germanium is emerging as a versatile material to realize devices capable of encoding, processing and transmitting quantum information. These devices leverage the special properties of holes in germanium, such as their inherently strong spin--orbit coupling and their ability to host superconducting pairing correlations. I will examine the materials science progress underpinning germanium-based planar heterostructures [2] and review the most significant experimental results demonstrating key building blocks for quantum technology [3,4], identifying the most promising avenues toward scalable quantum information processing in germanium-based systems.

[1] G. Scappucci et al, The germanium quantum information route,
Nat Rev Mater (2020). https://doi.org/10.1038/s41578-020-00262-z
[2] A. Sammak et al. Low disordered, stable, and shallow germanium quantum wells: a playground for spin and hybrid quantum technology, Advanced Functional Materials 1807613 (2019)
[3] N. Hendrickx et al, Fast two-qubit logic with holes in germanium, Nature 577, 487-491 (2020)
[4] N. Hendrickx et al, A four qubit germanium quantum processor, arXiv:2009.04268 (2020)