from qiskit import QuantumCircuit
from qiskit.quantum_info import Statevector
a, b = 1, 0  # two classical bits to send
qc = QuantumCircuit(2)
qc.h(0); qc.cx(0, 1)  # pre-shared Bell pair
if a: qc.z(0)        # phase encoding
if b: qc.x(0)        # bit-flip encoding
qc.cx(0, 1); qc.h(0) # Bell-basis decoder
print(qc.draw())
print(Statevector.from_instruction(qc).probabilities_dict())
# Expected decoded bitstring: '01' in Qiskit's displayed q1q0 order.