Python/quantum/superdense_coding.py.DISABLED.txt

"""
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 math

import qiskit
from qiskit import Aer, ClassicalRegister, QuantumCircuit, QuantumRegister, execute


def superdense_coding(bit_1: int = 1, bit_2: int = 1) -> qiskit.result.counts.Counts:
    """
    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:
        bit_1: bit 1 of classical information to send.
        bit_2: bit 2 of classical information to send.
    Returns:
        qiskit.result.counts.Counts: counts of send state.
    >>> superdense_coding(0,0)
    {'00': 1000}
    >>> superdense_coding(0,1)
    {'01': 1000}
    >>> superdense_coding(-1,0)
    Traceback (most recent call last):
        ...
    ValueError: inputs must be positive.
    >>> superdense_coding(1,'j')
    Traceback (most recent call last):
        ...
    TypeError: inputs must be integers.
    >>> superdense_coding(1,0.5)
    Traceback (most recent call last):
        ...
    ValueError: inputs must be exact integers.
    >>> superdense_coding(2,1)
    Traceback (most recent call last):
        ...
    ValueError: inputs must be less or equal to 1.
    """
    if isinstance(bit_1, str) or isinstance(bit_2, str):
        raise TypeError("inputs must be integers.")
    if (bit_1 < 0) or (bit_2 < 0):
        raise ValueError("inputs must be positive.")
    if (math.floor(bit_1) != bit_1) or (math.floor(bit_2) != bit_2):
        raise ValueError("inputs must be exact integers.")
    if (bit_1 > 1) or (bit_2 > 1):
        raise ValueError("inputs must be less or equal to 1.")

    # 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
    c_information = str(bit_1) + str(bit_2)

    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("aer_simulator")
    job = execute(quantum_circuit, backend, shots=1000)

    return job.result().get_counts(quantum_circuit)


if __name__ == "__main__":
    print(f"Counts for classical state send: {superdense_coding(1,1)}")