I know the definition of entangled state and separable state from Wikipedia, but I can't find the references that brought up the mathematical description of the entangled state and separable state. Is the definition brought up by someone?
3$\begingroup$ Did you see this answer to a previous question? quantumcomputing.stackexchange.com/a/2099/1837 $\endgroup$– DaftWullieNov 24, 2022 at 9:40
The name "entanglement" and the definition for pure states comes from Schrödinger 1935. The definition for mixed states comes from Werner 1989