  Superconductivity and topological quantum states are two frontier fields of
research in modern condensed matter physics. The realization of
superconductivity in topological materials is highly desired, however,
superconductivity in such materials is typically limited to two- or
three-dimensional materials and is far from being thoroughly investigated. In
this work, we boost the electronic properties of the quasi-one-dimensional
topological insulator bismuth iodide \b{eta}-Bi4I4 by applying high pressure.
Superconductivity is observed in \b{eta}-Bi4I4 for pressures where the
temperature dependence of the resistivity changes from a semiconducting-like
behavior to that of a normal metal. The superconducting transition temperature
Tc increases with applied pressure and reaches a maximum value of 6 K at 23
GPa, followed by a slow decrease. Our theoretical calculations suggest the
presence of multiple pressure-induced topological quantum phase transitions as
well as a structural-electronic instability.
