  Fault-tolerant quantum computation requires low physical-qubit gate errors.
Many approaches exist to reduce gate errors, including both hardware- and
control-optimization strategies. Dynamically corrected gates are designed to
cancel specific errors and offer the potential for high-fidelity gates, but
they have yet to be implemented in singlet-triplet spin qubits in semiconductor
quantum dots, due in part to the stringent control constraints in these
systems. In this work, we experimentally implement dynamically corrected gates
designed to mitigate hyperfine noise in a singlet-triplet qubit realized in a
Si/SiGe double quantum dot. The corrected gates reduce infidelities by about a
factor of three, resulting in gate fidelities above 0.99 for both identity and
Hadamard gates. The gate performances depend sensitively on pulse distortions,
and their specific performance reveals an unexpected distortion in our
experimental setup.
