No, Grover's algorithm does not require the answer to be already encoded in the qubits inside the black box gate. Grover's algorithm is a quantum algorithm that can be used to search an unsorted database or find the solution to an unstructured search problem.
In the context of Grover's algorithm, the black box gate, also known as the oracle, is used to mark the desired solution(s) in the search space. The oracle takes an input state and applies a phase flip to the states that correspond to the solution(s), while leaving the other states unchanged. The goal of Grover's algorithm is to amplify the amplitude of the solution(s) in the superposition of states by applying the oracle and a series of other quantum operations iteratively.
Initially, the qubits are prepared in a superposition of all possible states, and the oracle is applied to create constructive interference on the solutions. The algorithm then employs a set of quantum operations, including Hadamard transforms and phase flips, to amplify the amplitudes of the solution(s) and suppress the amplitudes of other states.
By repeating this process a specific number of times, determined by the size of the search space, the algorithm enhances the probability of measuring one of the solutions as the outcome. Grover's algorithm achieves a quadratic speedup compared to classical algorithms, making it more efficient for certain search problems.
In summary, Grover's algorithm does not require the answer to be pre-encoded in the qubits inside the black box gate. Instead, the algorithm uses the oracle gate iteratively to amplify the amplitude of the solution(s) in the search space and converge towards the correct answer.