# Copyright 2021 ProjectQ-Framework (www.projectq.ch)

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

# http://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

# pylint: skip-file

"""Example of a basic 'half-adder' circuit using an IonQBackend."""

import getpass

import random

import matplotlib.pyplot as plt

import projectq.setups.default

import projectq.setups.ionq

from projectq import MainEngine

from projectq.backends import IonQBackend

from projectq.libs.hist import histogram

from projectq.ops import CNOT, All, Barrier, Measure, Toffoli, X

def run_half_adder(eng):

"""Run the half-adder circuit."""

# allocate the quantum register to entangle

circuit = eng.allocate_qureg(4)

qubit1, qubit2, qubit3, qubit4 = circuit

result_qubits = [qubit3, qubit4]

# X gates on the first two qubits

All(X) | [qubit1, qubit2]

# Barrier

Barrier | circuit

# Cx gates

CNOT | (qubit1, qubit3)

CNOT | (qubit2, qubit3)

# CCNOT

Toffoli | (qubit1, qubit2, qubit4)

# Barrier

Barrier | circuit

# Measure result qubits

All(Measure) | result_qubits

# Flush the circuit (this submits a job to the IonQ API)

eng.flush()

# Show the histogram

histogram(eng.backend, result_qubits)

plt.show()

# return a random answer from our results

probabilities = eng.backend.get_probabilities(result_qubits)

random_answer = random.choice(list(probabilities.keys()))

return [int(s) for s in random_answer]

if __name__ == '__main__':

token = None

device = None

if token is None:

token = getpass.getpass(prompt='IonQ apiKey > ')

if device is None:

device = input('IonQ device > ')

backend = IonQBackend(

use_hardware=True,

token=token,

num_runs=200,

verbose=True,

device=device,

)

engine_list = projectq.setups.ionq.get_engine_list(

token=token,

device=device,

)

engine = MainEngine(backend, engine_list)

# run the circuit and print the result

print(run_half_adder(engine))