Create superdense_coding.py

quantum/superdense_coding.py

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+"""
+Build the superdense coding protocol. This quantum
+circuit can send two classical bits using one quantum
+bit. This circuit is designed using the Qiskit
+framework. This experiment run in IBM Q simulator 
+with 1000 shots.
+.
+References:
+https://qiskit.org/textbook/ch-algorithms/superdense-coding.html
+https://en.wikipedia.org/wiki/Superdense_coding
+"""
+
+import qiskit
+from qiskit import QuantumCircuit, QuantumRegister, ClassicalRegister, execute, Aer
+
+def superdense_coding(
+    c_information: str = '11'
+    ) -> qiskit.result.counts.Counts:
+    """
+    # >>> superdense_coding(c_information)
+    # The input refer to the classical message
+    # that you wants to send. {'00','01','10','11'}
+    # result for default values: {11: 1000}                         
+               ┌───┐          ┌───┐     
+    qr_0: ─────┤ X ├──────────┤ X ├─────
+          ┌───┐└─┬─┘┌───┐┌───┐└─┬─┘┌───┐
+    qr_1: ┤ H ├──■──┤ X ├┤ Z ├──■──┤ H ├
+          └───┘     └───┘└───┘     └───┘
+    cr: 2/══════════════════════════════                       
+    Args:
+        c_information: classical information to send.
+    Returns:
+        qiskit.result.counts.Counts: counts of send state.
+    """
+    # build registers
+    qr = QuantumRegister(2, 'qr')
+    cr = ClassicalRegister(2, 'cr')
+
+    quantum_circuit = QuantumCircuit(qr,cr)
+
+    # entanglement the qubits
+    quantum_circuit.h(1)
+    quantum_circuit.cx(1,0)
+
+    # send the information
+
+    if c_information == '11':
+        quantum_circuit.x(1)
+        quantum_circuit.z(1)
+    elif c_information == '10':
+        quantum_circuit.z(1)
+    elif c_information == '01':
+        quantum_circuit.x(1)
+    else:
+        quantum_circuit.i(1)
+
+    #unentangled the circuit
+    quantum_circuit.cx(1,0)
+    quantum_circuit.h(1)
+
+    # measure the circuit
+    quantum_circuit.measure(qr,cr)
+
+    backend = Aer.get_backend('qasm_simulator')
+    job = execute(quantum_circuit, backend, shots=1000)
+
+    return job.result().get_counts(quantum_circuit)
+
+if __name__ == "__main__":
+    print(f"Count for classical state send: {superdense_coding()}")