Ok, I'm working with the Pauli Matrices, and I've already gone through showing a few bits of information. I've got a good idea how to keep going, but I'm not exactly sure about this one-- say M= 1/2(alphaI + a*sigma) where alpha E C, a=(ax, ay, az) a complex vector, a*sigma=ax sigmax+ay sigmay+ az sigmz, and I is the identity matrix. So, an orthogonal projection means that for a matrix P, P^2 and P dagger are both equal to P, right? Supposedly alpha and a can beonstrained so that M is an orthogonal projection. How would I go about doing that? Thanks muchly!