- #1
Josh Conneely
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Homework Statement
Suppose a 2x2 matrix X (not necessarily hermitian, nor unitary) is written as
X = a0 + sigma . a (the sigma . a is a dot product between sigma and a)
where a0 and a1, a2 and a3 are numbers.
How on Earth does X represent a matrix? it's a number added to another number (dot product).