What is a controlled gate?

Question: What is the main idea of a controlled quantum gate? A) It always measures the control qubit first B) It runs only on classical bits C) It removes all phase information D) It applies an operation depending on the state of another qubit Correct: D Explanation: A controlled gate applies an operation to a target qubit depending on the control qubit. The CNOT gate is a common example, where the target flips if the control is |1⟩. Topic: quantum computing / controlled gates