  We studied geometric quantum speed limits (QSL) of a qubit subject to
decoherence in an ensemble of chloroform molecules in a Nuclear Magnetic
Resonance experiment. The QSL is a fundamental lower bound on the evolution
time for quantum systems undergoing general physical processes. To do so, we
controlled the system-reservoir interaction and the spin relaxation rates by
adding a paramagnetic salt, which allowed us to observe both Markovian and
non-Markovian open system dynamics for the qubit. We used two
distinguishability measures of quantum states to assess the speed of the qubit
evolution: the quantum Fisher information (QFI) and Wigner-Yanase skew
information (WY). For non-Markovian dynamics and low salt concentrations, we
observed crossovers between QSLs related to the QFI and WY metrics. The WY
metric sets the tighter QSL for high concentrations and Markovian dynamics. We
also show that QSLs are sensitive even to small fluctuations in spin
magnetization.
