Gate-Tunable Spin-Orbit Coupling in a Germanium Hole Double Quantum Dot

Abstract

Hole spins confined in semiconductor quantum dot systems have gained considerable interest for their strong spin-orbit interactions (SOIs) and relatively weak hyperfine interactions. Here, we experimentally demonstrate a tunable SOI in a double quantum dot in a germanium ($\mathrm{Ge}$) hut wire (HW), which could help to enable fast all-electric spin manipulations while suppressing unwanted decoherence. Specifically, we measure the transport spectra in the Pauli-spin-blockade regime in the double-quantum-dot device. By adjusting the interdot tunnel coupling, we obtain an electric-field-tuned spin-orbit length of ${l}_{\mathrm{SO}}$= 2.0--48.9 nm. This tunability of the SOI could pave the way toward the realization of high-fidelity qubits in $\mathrm{Ge}$ HW systems.