Now that we have already seen the states of the multi-qubit systems, we want to apply gates to them. But how do we do this? David will guide us through the steps and the possible kinds of gates. We will see the CNOT gate, a two-qubit gate that can generate entanglement!

• Product gates consist of single-qubit gates applied to different qubits in the multi-qubit state. The total gate can be obtained by the tensor product of the individual gates.
• By applying a CNOT gate to a product state we get an entangled state.
• The CNOT gate and a single Hadamard gate are used to make a Bell State, which is a two-qubit entangled state. Depending on the input state we will get one or another Bell state.