Worked Problems in Physics

Nielsen and Chuang Exercise 2.32

Posted in Nielsen/Chuang by rpmuller on March 7, 2010

Exercise 2.32 Show that {A\otimes B} is a projector if {A,B} are projectors.

We want to show that {P^2=P} here:

\displaystyle  (A\otimes B)^2 = A^2\otimes B^2 = A\otimes B

Hence {A\otimes B} is a projector if {A,B} are.