When a qubit is measured in the standard basis, the result is a classical bit. The Born rule describes the norm-squared correspondence between amplitudes and probabilitieswhen measuring a qubit , the state collapses to with probability , or to with probability . Any valid qubit state has coefficients and such that . As an example, measuring the qubit would produce either or with equal probability.
When a qubit is measured in the standard basis, the result is a classical bit. The Born rule describes the norm-squared correspondence between amplitudes and probabilitieswhen measuring a qubit , the state collapses to with probability , or to with probability  Any valid, qubit state has coefficients and such that . As an example measuring the. qubit would produce either or with equal probability.