  The structural or electronic symmetry breaking of the host lattice is a
recurrent phenomenon in many quantum materials, including superconductors. Yet,
how these broken symmetry states affect the electronic pair wave function of
superconductivity have been rarely elucidated. Here, using low-temperature
scanning tunneling microscopy and first-principles calculations, we identify
the broken rotational symmetry via stripe ordering on the (001) surface of
perovskite BaBi3 films grown by molecular beam epitaxy, and show that it
consequently leads to anisotropic superconductivity with twofold symmetry. In
contrast, the structural disorder smears out the anisotropy of electron pairing
and fills superconducting subgap density of states as the film thickness is
reduced. A quasi-long range model of superconducting fluctuations is revealed
to describe the tunneling conductance spectra of thin BaBi3 films well, and to
exemplify how disorders contribute to the low-energy quasiparticle excitations
in superconductors. Our findings help understand the effects of symmetry
breaking states and disorders on superconductivity, particularly the existing
tunneling conductance spectra there.
