 Consider again the quantum CNOT gate, with two orthogonal qubits \(\ket{0}\) and \(\ket{1}\) as possible inputs for the control, and \(\ket{0}\) as the input for the target. One can think of the input control and output target qubits, respectively, as the argument and associated value of a function. This CNOT function associates the value 0 with the argument 0 and the value 1 with the argument 1. For a linear superposition of the orthogonal qubits with equal coefficients as input to the control, and the qubit \(\ket{0}\) as the input to the target, the output is the entangled state \(\ket{0} \ket{0}\) + \(\ket{1} \ket{1}\) (ignoring the coefficients, for simplicity). This is a linear superposition in which the first term represents the argument 0 and associated value 0 of the CNOT function, and the second term represents the argument 1 and associated value 1 of the CNOT function. The entangled state represents all possible arguments and corresponding values of the function as a linear superposition, but this information is not accessible. What can be shown to be accessible, by a suitable choice of quantum gates, is information about whether or not the function has certain global properties. This information is obtainable without reading out the evaluation of any individual arguments and values. (Indeed, accessing information in the entangled state about a global property of the function will typically require losing access to all information about individual arguments and values.)