  The Advanced LIGO and Virgo detectors opened a new era to study black holes
(BHs) in our Universe. A population of stellar-mass binary BHs (BBHs) are
discovered to be heavier than previously expected. These heavy BBHs provide us
an opportunity to achieve multiband observation with ground-based and
space-based gravitational-wave (GW) detectors. In this work, we use BBHs
discovered by the LIGO/Virgo Collaboration as indubitable examples, and study
in great detail the prospects for multiband observation with GW detectors in
the near future. We apply the Fisher matrix to spinning, non-precessing
inspiral-merger-ringdown waveforms, while taking the motion of space-based GW
detectors fully into account. Our analysis shows that, detectors with decihertz
sensitivity are expected to log stellar-mass BBH signals with very large
signal-to-noise ratio, and provide accurate parameter estimation, including the
sky location and time to coalescence. Furthermore, the combination of multiple
detectors will achieve unprecedented measurement of BBH properties. As an
explicit example, we present the multiband sensitivity to the generic dipole
radiation for BHs, which is vastly important for the equivalence principle in
the foundation of gravitation, in particular for those theories that predict
curvature-induced scalarization of BHs.
