格罗弗算法是一种量子算法，它在搜索包含 $N$ 个条目的未排序数据库时，能够提供相对于经典算法的二次加速。经典算法的时间复杂度为 $O(N)$，而格罗弗算法的时间复杂度为 $O(\sqrt{N})$。这意味着，对于大型数据库，格罗弗算法可以显著提高搜索效率。
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Using Grover's algorithm with four qubits to search for the value 90 in a hypothetical table