This is a little package that will help with learning how quantum spin and
entanglement work. It is meant to complement some of the "theoretical
minimum" lectures and other web resources.
* https://en.wikipedia.org/wiki/Pauli_matrices
* https://en.wikipedia.org/wiki/Triplet_state
* https://en.wikipedia.org/wiki/Von_Neumann_entropy
* Book: Quantum Mechanics - The Theoretical Minimum, Leanoard Susskind and
  Art Friedman, Basic Books, 2014. (mostly chapters 6&7)
* http://theoreticalminimum.com/courses/quantum-mechanics/2012/winter/lecture-6
  and lecture 7