Quantum-computing/Deutsch-Jozsa Algorithm.py at main · graph90/Quantum-computing · GitHub

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import numpy as np

from qiskit import IBMQ, BasicAer
from qiskit.providers.ibmq import least_busy
from qiskit import QuantumCircuit, execute
from qiskit.tools.jupyter import *
provider = IBMQ.load_account()
from qiskit.visualization import plot_histogram

def dj_oracle(case, n):
    oracle_qc = QuantumCircuit(n+1)
    if case == "balanced":
        for qubit in range(n):
            oracle_qc.cx(qubit, n)
    if case == "constant":
        output = np.random.randint(2)
        if output == 1:
            oracle_qc.x(n)
    oracle_gate = oracle_qc.to_gate()
    oracle_gate.name = "Oracle"
    return oracle_gate

def dj_algo(n, case = 'random'):
    dj_circuit = QuantumCircuit(n+1, n)
    for qubit in range(n):
        dj_circuit.h(qubit)
    dj_circuit.x(n)
    dj_circuit.h(n)
    if case == 'random':
        random = np.random.randint(2)
        if random == 0:
            case = "constant"
        else:
            case = 'balanced'
    oracle = dj_oracle(case, n)
    dj_circuit.append(oracle, range(n+1))
    for i in range(n):
        dj_circuit.h(i)
        dj_circuit.measure(i, i)
    return dj_circuit

n = 4
dj_circuit = dj_algo(n)
dj_circuit.draw()

backend, shots, dj_circuit = BasicAer.get_backend('qasm_simulator'), 1024, dj_algo(n)
plot_histogram(execute(dj_circuit, backend=backend, shots=shots).result().get_counts())

backend = least_busy(provider.backends(filters=lambda x: x.configuration().n_qubit >= (n+1) and not x.configuration().simulator and x.status().operational==True))

print("least busy backend: ", backend)

%qiskit_job_watcher
dj_circuit = dj_algo(n)
backend = provider.get_backend("ibmq_belem")
job = execute(dj_circuit, backend=backend, shots=shots, optimization_level=3)

results = job.result()
answer = results.get_counts()