Lucy.py

import matplotlib.pyplot as plt
from braket.circuits import Circuit
from braket.aws import AwsDevice
from braket.tracking import Tracker

# function to build a GHZ state
def ghz_circuit(n_qubits):
    """
    function to return a GHZ circuit ansatz
    input: number of qubits
    """

    # instantiate circuit object
    circuit = Circuit()
    
    # add Hadamard gate on first qubit
    circuit.h(0)

    # apply series of CNOT gates
    for ii in range(0, n_qubits-1):
        circuit.cnot(control=ii, target=ii+1)

    return circuit

device = AwsDevice("arn:aws:braket:eu-west-2::device/qpu/oqc/Lucy")

##

with Tracker() as tracker:
    tasks = {}
    results = {}
    # submit tasks in parallel 
    for n_qubits in range(2,9):
        ghz = ghz_circuit(n_qubits)
        tasks[n_qubits] = device.run(ghz, shots=1000)
        print('{}-qubit task {}'.format(n_qubits,tasks[n_qubits].state()))

    print('\n')

print('${}'.format(tracker.qpu_tasks_cost()))

##

for n_qubits in range(2, 9):

    # check the status of the task and wait until the task is complete
    status = tasks[n_qubits].state()
    while status != 'COMPLETED':
        status = tasks[n_qubits].state()

    results[n_qubits] = tasks[n_qubits].result()
    # get the 'shots' parameter from metadata
    num_shots = results[n_qubits].task_metadata.shots
    # get the measurement counts
    counts = results[n_qubits].measurement_counts

    print('{}-qubit task {}.'.format(n_qubits, status))
    print("Measured qubits: {}".format(results[n_qubits].measured_qubits))
    
    # plot using Counter
    plt.bar(counts.keys(), counts.values());
    plt.xlabel('bitstrings');
    plt.ylabel('counts'); 
    plt.show()

manual-qubit-lucy.py

# function to build GHZ state
def ghz_circuit_lucy(n_qubits=7):
    """
    function to return GHZ circuit ansatz
    input: number of qubits
    """

    # instantiate circuit object
    circuit = Circuit()
    
    # add Hadamard gate on first qubit
    circuit.h(0)

#     # apply series of CNOT gates
#     for ii in range(0, n_qubits-1):
#         circuit.cnot(control=ii, target=ii+1)
        
    circuit.cnot(0, 1).cnot(1, 2).cnot(2, 3)
    circuit.cnot(0, 7).cnot(7, 6).cnot(6, 5)

    return circuit

##

device = AwsDevice("arn:aws:braket:eu-west-2::device/qpu/oqc/Lucy")

ghz = ghz_circuit_lucy()

task = device.run(ghz, shots=1000, disable_qubit_rewiring=True)
result = task.result()
counts = result.measurement_counts

# plot using Counter
plt.bar(counts.keys(), counts.values());
plt.xlabel('bitstrings');
plt.ylabel('counts'); 
plt.show()