  We study the formation of quantum droplets in the mixture of a
single-component Bose-Einstein condensate (BEC), and a two-species Fermi
superfluid across a wide Feshbach resonance. With repulsive boson-boson and
attractive boson-fermion interactions, we show that quantum droplets can be
stabilized by attractive fermion-fermion interactions in the
Bardeen-Cooper-Schieffer (BCS) side of the resonance, and can also exist in
deep BEC regime under weak boson-fermion interactions. We map out the phase
diagram for stable droplets with respect to the boson-boson and boson-fermion
interactions, and discuss the role of different types of quantum fluctuations
in the relevant regions of the BCS-BEC crossover. Our work reveals the impact
of fermion pairing on the formation of quantum droplets in Bose-Fermi mixtures,
and provides a useful guide for future experiments.
