Calculating a spectral norm - Quantum Computing Stack Exchange

Personally, I'd jump straight to Mathematica. It took me all of a minute: zero = ({ {1, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0, 0, ...