Quantum bits, or qubits, are indeed different from classical bits in that they can exist in a superposition of states, representing both 0 and 1 simultaneously. However, the superposition is not due to real and imaginary parts of the qubit state.
In a quantum system, a qubit can be represented by a mathematical object known as a quantum state vector, which is a complex vector. The superposition arises from the ability of the quantum state vector to combine different probability amplitudes for the states 0 and 1. These probability amplitudes are complex numbers, and the real and imaginary parts of these complex numbers represent the magnitude and phase of the probability amplitudes, respectively.
When a qubit is measured, its quantum state collapses to either the 0 state or the 1 state with a certain probability determined by the amplitudes. The actual outcome of the measurement is probabilistic and follows the rules of quantum mechanics.
So, to clarify, the superposition of qubits is not due to real and imaginary parts of the qubit state itself, but rather the complex probability amplitudes associated with the different states that a qubit can be in.