Speaker
Description
Planar Ge/SiGe heterostructures are integral to quantum technologies, particularly as platforms for quantum computation using hole-spin qubits. Compressive strain applied to germanium alters the energy dispersion of holes at the $\Gamma$-point, lifting the degeneracy between heavy and light holes by $130$ meV. This results in two two-fold degenerate bands, characterized by effective spins $|j_z|=3/2$ and $|j_z|=1/2$. We confirm this energy diagram using soft X-ray ARPES, providing direct access to momentum-resolved energy levels. First-principles calculations quantitatively reproduce the experimental band structure and energy splittings, enhancing our understanding of the quantum functionality of Ge/SiGe heterostructures. Additionally, we explore the utility of soft X-ray ARPES in studying semiconductor/superconductor heterostructures, such as Al/Ge/SiGe.
