Understanding the interactions between elementary particles and mapping out the internal structure of the hadrons are of fundamental importance in high energy nuclear and particle physics. This thesis concentrates on the strong interaction, described by Quantum Chromodynamics (QCD). We introduce a novel concept called ``polarized jet fragmentation functions'' and develop the associated theory framework known as QCD factorization which allows us to utilize jet substructure to probe spin dynamics of hadrons, especially nucleon's three-dimensional imaging. Furthermore, non-perturbative QCD studies, particularly of the QCD phase diagram, are important for understanding the properties of hadrons. The development of quantum computing and simulators can potentially improve the accuracy of finite-temperature simulations and allow researchers to explore extreme temperatures and densities in more detail. In this thesis, I present my work in two aspects of QCD studies: (1) investigating the nucleon structure using polarized jet fragmentation functions and (2) illustrating how to apply quantum computing techniques for studying phase diagram of a low energy QCD model. The first category investigates phenomena such as hadron production inside jets, spin asymmetries, etc., providing valuable insight into the behavior of quarks and gluons in hadrons. The second category provides potential applications of quantum computing in QCD and explores the non-perturbative nature of QCD.