00:01
All right, in this exercise we have here to determine which of the following matrices are unitary.
00:08
To find out if a matrix is unitary or not, we must fulfill this condition.
00:16
The product of matrix a by the hermitian matrix a must yield this identity.
00:25
So the most important thing of this exercise and this exercise is actually not forgetting what really means to write the hermitian matrix.
00:36
So let's do it.
00:37
So here we have the a matrix.
00:40
Now let's write the hermitian one.
00:43
So it's going to be minus 1 i over 2 square root of 3 over 2 minus square root of 3 over 2 minus square root of 3 over 2, i over 2.
01:00
Making this product, we're going to find the identity matrix.
01:07
So this is a unitary matrix.
01:11
Note that the diagonal is always 1.
01:17
For the matrix b, we have a product before, actually a factor 1 over 2 times the matrix b...