Measurement of the out-of-plane g-factor in strained Ge/SiGe using single-hole quantum dots.

Characterization of Shallow, Undoped Ge/SiGe Quantum Wells Commercially Grown on 8-in. (100) Si Wafers

“…Holes in Ge/SiGe quantum well heterostructures have been shown to have excellent transport properties such as low percolation densities of around 2.1 × 10 10 cm –2 and peak mobilities of around 1 × 10 6 cm 2 V –1 s –1 at a temperature of 1.7 K, indicating low levels of disorder. Specifically, holes in Ge are attractive because the large spin–orbit interaction allows electric control of the spin, , while the p-like orbital symmetry of holes is expected to be robust against hyperfine interactions, which can be further suppressed through isotopic purification of Ge. , For qubit applications, further potential advantages of holes in Ge, compared to electrons in Si, include a small effective mass which relaxes fabrication constraints, lack of valley degeneracy in the valence band, and large out-of-plane and tunable effective g -factors. , Altogether, these properties make Ge/SiGe quantum well heterostructures a leading candidate for quantum processors with demonstrations of singlet–triplet qubits and single-hole qubits up to a four-qubit quantum processor …”

“…11,12 For qubit applications, further potential advantages of holes in Ge, compared to electrons in Si, include a small effective mass 13 which relaxes fabrication constraints, lack of valley degeneracy in the valence band, and large out-ofplane and tunable effective g-factors. 14,15 Altogether, these properties make Ge/SiGe quantum well heterostructures a leading candidate for quantum processors with demonstrations of singlet−triplet qubits 16 and single-hole qubits 17 up to a fourqubit quantum processor. 18 With the recent surge of interest in Ge/SiGe quantum well heterostructures, establishing high-quality materials intended for spintronic and quantum devices beyond the universitybased research setting is a necessary step toward advanced applications.…”