  Current superconducting quantum processors require strategies for coping with
material defects and imperfect parameter targeting in order to scale up while
maintaining high performance. To that end, in-situ control of qubit frequencies
with magnetic flux can be used to avoid spurious resonances. However, increased
dephasing due to 1/f flux noise limits performance at all of these operating
points except for noise-protected sweet spots, which are sparse under DC flux
bias and monochromatic flux modulation. Here we experimentally demonstrate that
two-tone flux modulation can be used to create a continuum of dynamical sweet
spots, greatly expanding the range of qubit frequencies achievable while
first-order insensitive to slow flux noise. To illustrate some advantages of
this flexibility, we use bichromatic flux control to reduce the error rates and
gate times of parametric entangling operations between transmons. Independent
of gate scheme, the ability to use flux control to freely select qubit
frequencies while maintaining qubit coherence represents an important step
forward in the robustness and scalability of near-term superconducting qubit
devices.
