# Really basic quantum mechanics question

1. Apr 24, 2010

### barnflakes

I keep reading about qubits, and they say that if a qubit is represented as $$\arrowvert \phi \rangle = \alpha|0\rangle + \beta|1\rangle$$ then the probability of it being in the 0 state is $$|\alpha^2|$$ and similarly for the 1 state.

My question is how do they get this value? Is it from $$|\langle 0 | \phi \rangle|^2$$ ?

2. Apr 24, 2010

Yup!