For an understanding of quantum physics, see the definition of “quantum mechanics.” Often, the two terms are used to mean the same thing. However, their connotations are slightly different.
“Quantum physics” is a more general term than “quantum mechanics.” Using the term “quantum mechanics,” emphasizes the mathematical equations of this field. From 1900 to the mid-1920’s, prior to the development of key equations, this field was called “quantum theory.” In the 1920’s and 1930’s, when key equations were developed, the field became known as “quantum mechanics.” This is on analogy with the equations of classical mechanics developed by Isaac Newton. The term “quantum physics” describes the field during both periods or, more loosely, can simply be used as a synonym for “quantum mechanics.”