In high energy heavy-ion collisions, heavy quarks mostly charm and bottom quarks are produced in initial hard collisions, they are excellent probes the produced medium from heavy-ion collisions. PHENIX and STAR experiments at RHIC have been observed many interesting properties of nuclear matters in various size of collision systems with heavy quarks. The journey starts from p+p collisions where we can test our theoretical understanding of heavy quark production, passing through p/d+A collisions where we can study intrinsic properties of nuclear matter, toward heavy ion collisions where the hot nuclear matter effects are dominating. By the virtue of successful operation of silicon vertex tracking systems in recent years, we could start to study the behavior of charm and bottom quarks separately inside the nuclear matters. In this seminar, interesting results of heavy quarks in various collision systems will be discussed. In addition, a new experiment (sPHENIX) for more precise studies for the nuclear matters will be introduced.