CNOT gate implementation using Qiskit. The example prepares the Bell state $\lvert\Phi^+\rangle = \frac{1}{\sqrt{2}}(\lvert 00\rangle + \lvert 11\rangle)$.

from qiskit import QuantumCircuit
from qiskit.quantum_info import Statevector
 
qc = QuantumCircuit(2)
qc.h(0)     # |00> -> |+0>
qc.cx(0, 1) # CNOT: control=q0, target=q1 -> Bell state
print(Statevector(qc))
# Statevector([0.70710678+0.j, 0.+0.j, 0.+0.j, 0.70710678+0.j], dims=(2, 2))