Ancilla Qubit

An ancilla qubit is an extra qubit introduced into a quantum circuit to assist with computation, often initialized in a known state like is a basis state.
Learn more about . It is used as temporary workspace for tasks such as error correction, implementing quantum gates or extracting information without disturbing the main data qubits. After use, ancilla qubits are typically uncomputed, measured or reset so they don’t carry unintended information forward.