  While the zeros of complex partition functions, such as Lee-Yang zeros and
Fisher zeros, have been instrumental in characterizing temperature-driven phase
transitions, the extension of this concept to zero temperature remains an open
and active topic. In this paper, we introduce the concept of
Imaginary-Temperature Zeros (ITZs) by calculating the zeros of the
imaginary-temperature partition function. We delve into the properties of ITZs
for the transverse-field Ising chain, and find that the ITZs are distributed in
sectorial structures, accompanied by universal singular behaviors for such
quantities as the edge density of ITZs and the magnetization. These
singularities remarkably differ from those in the Lee-Yang theory, and are
demonstrated to be intimately related to quantum criticality and the Ising
critical exponents. We further illuminate the correspondence between ITZs and
the zeros of the spectrum form factor, which offers a practical way for
detecting ITZs and zero-temperature phase transitions through quantum dynamics.
