  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 (Ge) hut wire (HW), which
could help 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
lso = 2.0 - 48.9 nm. This tunability of the SOI could pave the way toward the
realization of high-fidelity qubits in Ge HW systems.
