X gate implementation using Qiskit.

from qiskit import QuantumCircuit
from qiskit.quantum_info import Statevector
 
qc = QuantumCircuit(1)
qc.x(0)  # |0> -> |1>
print(Statevector(qc))
# Statevector([0.+0.j, 1.+0.j], dims=(2,))