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IBM Q Experience 用户指南中的Bloch 球体示例应在末尾显示一个图。当我运行示例时，它不会显示绘图。

我可以内联（在 jupyter 中）绘制电路和其他图，但是在这个中绘图对我不起作用。

代码（从示例页面完全复制）如下所示。

我的环境是：

Fedora Core 30
Qiskit 0.8.2
Matplotlib 3.1.0
Python 3.7.3
Conda 4.6.11（conda-build 版本：3.17.8）
jupyter core：4.5.0
jupyter-notebook：5.7.8
qtconsole：未安装
ipython：7.5。 0
ipykernel：5.1.1
jupyter 客户端：5.2.4
jupyter lab：未安装
nbconvert：5.5.0
ipywidgets：7.4.2
nbformat：4.4.0
traitlets：4.3.2

# quantum_phase_bloch.py
import numpy as np

from qiskit import QuantumCircuit, QuantumRegister, ClassicalRegister, execute, Aer
from qiskit.tools.visualization import plot_bloch_vector

# Define the Quantum and Classical Registers
q = QuantumRegister(1)
c = ClassicalRegister(1)

# Build the circuits
pre = QuantumCircuit(q, c)
pre.h(q)
pre.barrier()

meas_x = QuantumCircuit(q, c)
meas_x.barrier()
meas_x.h(q)
meas_x.measure(q, c)

meas_y = QuantumCircuit(q, c)
meas_y.barrier()
meas_y.s(q).inverse()
meas_y.h(q)
meas_y.measure(q, c)

meas_z = QuantumCircuit(q, c)
meas_z.barrier()
meas_z.measure(q, c)

bloch_vector = ['x', 'y', 'z']
exp_vector = range(0, 21)
circuits = []
for exp_index in exp_vector:
    middle = QuantumCircuit(q, c)
    phase = 2*np.pi*exp_index/(len(exp_vector)-1)
    middle.u1(phase, q)
    circuits.append(pre + middle + meas_x)
    circuits.append(pre + middle + meas_y)
    circuits.append(pre + middle + meas_z)

# Execute the circuit
job = execute(circuits, backend = Aer.get_backend('qasm_simulator'), shots=1024)
result = job.result()

# Plot the result
for exp_index in exp_vector:
    bloch = [0, 0, 0]
    for bloch_index in range(len(bloch_vector)):
        data = result.get_counts(circuits[3*exp_index+bloch_index])
        try:
            p0 = data['0']/1024.0
        except KeyError:
            p0 = 0
        try:
            p1 = data['1']/1024.0
        except KeyError:
            p1 = 0
        bloch[bloch_index] = p0-p1
    plot_bloch_vector(bloch)
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1 回答 1

0

ImportanceOfBeingErnest提供的最后一个链接显示了一个解决问题的函数（它可能不是最好的方法，但它帮助了我，所以我在这里为其他人发布了修改后的代码）。

修改后的代码是：

# quantum_phase_bloch.py
%matplotlib inline
import matplotlib.pyplot as plt

def show_figure(fig):
    # See https://github.com/Qiskit/qiskit-terra/issues/1682
    new_fig = plt.figure()
    new_mngr = new_fig.canvas.manager
    new_mngr.canvas.figure = fig
    fig.set_canvas(new_mngr.canvas)
    plt.show(fig)

import numpy as np

from qiskit import QuantumCircuit, QuantumRegister, ClassicalRegister, execute, Aer
from qiskit.tools.visualization import plot_bloch_vector

# Define the Quantum and Classical Registers
q = QuantumRegister(1)
c = ClassicalRegister(1)

# Build the circuits
pre = QuantumCircuit(q, c)
pre.h(q)
pre.barrier()

meas_x = QuantumCircuit(q, c)
meas_x.barrier()
meas_x.h(q)
meas_x.measure(q, c)

meas_y = QuantumCircuit(q, c)
meas_y.barrier()
meas_y.s(q).inverse()
meas_y.h(q)
meas_y.measure(q, c)

meas_z = QuantumCircuit(q, c)
meas_z.barrier()
meas_z.measure(q, c)

bloch_vector = ['x', 'y', 'z']
exp_vector = range(0, 21)
circuits = []
for exp_index in exp_vector:
    middle = QuantumCircuit(q, c)
    phase = 2*np.pi*exp_index/(len(exp_vector)-1)
    middle.u1(phase, q)
    circuits.append(pre + middle + meas_x)
    circuits.append(pre + middle + meas_y)
    circuits.append(pre + middle + meas_z)

# Execute the circuit
job = execute(circuits, backend = Aer.get_backend('qasm_simulator'), shots=1024)
result = job.result()

# Plot the result
for exp_index in exp_vector:
    bloch = [0, 0, 0]
    phase = 2*np.pi*exp_index/(len(exp_vector)-1)
    phase_deg = phase / (2.0*np.pi) * 360.0
    for bloch_index in range(len(bloch_vector)):
        data = result.get_counts(circuits[3*exp_index+bloch_index])
        try:
            p0 = data['0']/1024.0
        except KeyError:
            p0 = 0
        try:
            p1 = data['1']/1024.0
        except KeyError:
            p1 = 0
        bloch[bloch_index] = p0-p1
    show_figure(plot_bloch_vector(bloch, title='Bloch sphere with phase {:.1f} degrees'.format(phase_deg)))
于 2019-07-09T05:01:24.740 回答