  Qubits require a compromise between operation speed and coherence. Here, we
demonstrate a compromise-free singlet-triplet (ST) qubit, where the qubit
couples maximally to the driving field while simultaneously coupling minimally
to the dominant noise sources. The qubit is implemented in a crystal-phase
defined double-quantum dot in an InAs nanowire. Using a superconducting
resonator, we measure the spin-orbit interaction (SOI) gap, the spin-photon
coupling strength and the qubit decoherence rate as a function of the in-plane
magnetic-field orientation. We demonstrate a spin qubit sweet spot maximizing
the dipolar coupling and simultaneously minimizing the decoherence. Our
theoretical description postulates phonons as the most likely dominant noise
source. The compromise-free sweet spot originates from the SOI suggesting that
it is not restricted to this material platform, but might find applications in
any material with SOI. These findings pave the way for enhanced engineering of
these nanomaterials for next-generation qubit technologies.
