Plus state, |+⟩

The |+⟩ state carries two amplitudes of about +0.71, so the two amplitudes have the same sign. The squares of that exact split are a half each, and 0.71 is the two-decimal rounding of the amplitude rather than a number whose square is one half.

The |+⟩ state is the equal superposition of |0⟩ and |1⟩ with matching signs, written as a ket whose label is a plus. A Hadamard on the state certain to read 0 writes two amplitudes of about +0.71, one for a reading of 0 and one for a reading of 1, and the squares of those exact amplitudes are a half each.

Keith reads the plus as both answers at once, with a lean toward 0. The plus is the sign the two amplitudes share, and the chances are even. It is one definite state, not two answers at once, and the globe draws it on the equator at the tip of the amber arrow.

Plus state, |+⟩

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