The basis method of encoding qubits and using them as classical bits are fundamentally different concepts in quantum computing. While classical bits can be in either state 0 or 1, qubits can exist in a superposition of states, which is a unique property of quantum mechanics.
In classical computing, information is processed using bits, which are binary entities that can represent either a 0 or a 1. These bits can be combined and manipulated using logic gates to perform computations. Each bit has a definite value that can be measured.
On the other hand, qubits are the fundamental building blocks of quantum computing. Qubits can be in a superposition, meaning they can simultaneously exist in multiple states. The basis method refers to the choice of basis in which the qubits are encoded. The two common bases used are the computational basis (|0⟩ and |1⟩) and the superposition basis (|+⟩ and |-⟩). The computational basis states correspond to the classical 0 and 1, while the superposition basis states are the equal superposition of 0 and 1.
Superposition allows qubits to hold and process multiple states simultaneously, leading to the potential for parallel computation. For example, a qubit in a superposition of |0⟩ and |1⟩ can represent both 0 and 1 at the same time. The power of quantum computing comes from the ability to manipulate and exploit these superposition states to perform complex computations more efficiently than classical computers in certain cases.
When a measurement is performed on a qubit, it "collapses" into one of the basis states with a certain probability. The measurement outcome is probabilistic, and the probabilities are determined by the amplitudes of the superposition. This introduces inherent uncertainty in the measurement results, which is a significant departure from classical bits.
In summary, the basis method of encoding qubits allows for the representation of both classical bits and superposition states. The possibility of superposition arises from the unique properties of quantum mechanics, enabling qubits to exist in multiple states simultaneously and perform parallel computations.