density matrix
This demonstrates that, as expected, the reduced density matrix for an entangled pure ensemble is a mixed ensemble. Also not surprisingly, the density matrix of A for the pure product state 




|

ψ

⟩

A


⊗

|

ϕ

⟩

B




{\displaystyle |\psi \rangle _{A}\otimes |\phi \rangle _{B}}

 discussed above is
