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Update qsphere plots to show state labels and phases #4384

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merged 12 commits into from
May 13, 2020
+50 −10
Merged

Update qsphere plots to show state labels and phases #4384

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146e36f
update qsphere plots to show state labels and phases, switch to degrees
May 4, 2020
23010be
remove whitespace for style and lint tests, add docstrings
May 4, 2020
2b6eddb
add use_degrees and fix 180 degrees overlap with phase circle
May 4, 2020
a97e89c
changed default to radians
May 4, 2020
f01b694
remove stray print, clean up code, default radians
May 12, 2020
56d3208
Merge branch 'master' into master
May 12, 2020
28cdbed
add release note
May 12, 2020
868fedf
Merge remote-tracking branch 'origin/master'
May 12, 2020
4ce87fb
Merge branch 'master' into master
jaygambetta May 12, 2020
17a9390
Merge branch 'master' into master
mergify[bot] May 12, 2020
cd8291d
remove prelude section from release notes
May 12, 2020
b3042f3
Merge remote-tracking branch 'origin/master'
May 12, 2020
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63 changes: 49 additions & 14 deletions qiskit/visualization/state_visualization.py
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@
import numpy as np
from scipy import linalg
from qiskit.quantum_info.operators.pauli import pauli_group, Pauli
from qiskit.circuit.tools.pi_check import pi_check
from .matplotlib import HAS_MATPLOTLIB

if HAS_MATPLOTLIB:
Expand Down Expand Up @@ -630,7 +631,8 @@ def phase_to_rgb(complex_number):
return rgb


def plot_state_qsphere(rho, figsize=None, ax=None):
def plot_state_qsphere(rho, figsize=None, ax=None, show_state_labels=True,
show_state_phases=True, use_degrees=True):
"""Plot the qsphere representation of a quantum state.
Here, the size of the points is proportional to the probability
of the corresponding term in the state and the color represents
Expand All @@ -644,6 +646,12 @@ def plot_state_qsphere(rho, figsize=None, ax=None):
the visualization output. If none is specified a new matplotlib
Figure will be created and used. Additionally, if specified there
will be no returned Figure since it is redundant.
show_state_labels (bool): An optional boolean indicating whether to
show labels for each basis state.
show_state_phases (bool): An optional boolean indicating whether to
show the phase for each basis state.
use_degrees (bool): An optional boolean indicating whether to use
radians or degrees for the phase values in the plot.

Returns:
Figure: A matplotlib figure instance if the ``ax`` kwag is not set
Expand Down Expand Up @@ -774,6 +782,24 @@ def plot_state_qsphere(rho, figsize=None, ax=None):
if yvalue >= 0.1:
alfa = 1.0 - yvalue

if prob > 0 and show_state_labels:
rprime = 1.3
angle_theta = np.arctan2(np.sqrt(1 - zvalue ** 2), zvalue)
xvalue_text = rprime * np.sin(angle_theta) * np.cos(angle)
yvalue_text = rprime * np.sin(angle_theta) * np.sin(angle)
zvalue_text = rprime * np.cos(angle_theta)
element_text = '$\\vert' + element + '\\rangle$'
if show_state_phases:
element_angle = (np.angle(state[i]) + (np.pi * 4)) % (np.pi * 2)
if use_degrees:
element_text += '\n$%.1f^\\circ$' % (element_angle * 180/np.pi)
else:
element_angle = pi_check(element_angle, ndigits=3, output='latex')
print(element_angle)
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element_text += '\n$%s$' % (element_angle)
ax.text(xvalue_text, yvalue_text, zvalue_text, element_text,
ha='center', va='center', size=12)

ax.plot([xvalue], [yvalue], [zvalue],
markerfacecolor=colorstate,
markeredgecolor=colorstate,
Expand Down Expand Up @@ -807,21 +833,30 @@ def plot_state_qsphere(rho, figsize=None, ax=None):
ax2 = fig.add_subplot(gs[2:, 2:])
ax2.pie(theta, colors=sns.color_palette("hls", n), radius=0.75)
ax2.add_artist(Circle((0, 0), 0.5, color='white', zorder=1))
ax2.text(0, 0, 'Phase', horizontalalignment='center',
verticalalignment='center', fontsize=14)

offset = 0.95 # since radius of sphere is one.

ax2.text(offset, 0, r'$0$', horizontalalignment='center',
verticalalignment='center', fontsize=14)
ax2.text(0, offset, r'$\pi/2$', horizontalalignment='center',
verticalalignment='center', fontsize=14)

ax2.text(-offset, 0, r'$\pi$', horizontalalignment='center',
verticalalignment='center', fontsize=14)

ax2.text(0, -offset, r'$3\pi/2$', horizontalalignment='center',
verticalalignment='center', fontsize=14)
if use_degrees:
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ax2.text(0, 0, 'Phase\n(Deg)', horizontalalignment='center',
verticalalignment='center', fontsize=14)
ax2.text(offset, 0, r'0', horizontalalignment='center',
verticalalignment='center', fontsize=14)
ax2.text(0, offset, r'90', horizontalalignment='center',
verticalalignment='center', fontsize=14)
ax2.text(-offset, 0, r'180 ', horizontalalignment='center',
verticalalignment='center', fontsize=14)
ax2.text(0, -offset, r'270', horizontalalignment='center',
verticalalignment='center', fontsize=14)
else:
ax2.text(0, 0, 'Phase', horizontalalignment='center',
verticalalignment='center', fontsize=14)
ax2.text(offset, 0, r'$0$', horizontalalignment='center',
verticalalignment='center', fontsize=14)
ax2.text(0, offset, r'$\pi/2$', horizontalalignment='center',
verticalalignment='center', fontsize=14)
ax2.text(-offset, 0, r'$\pi$', horizontalalignment='center',
verticalalignment='center', fontsize=14)
ax2.text(0, -offset, r'$3\pi/2$', horizontalalignment='center',
verticalalignment='center', fontsize=14)

if return_fig:
if get_backend() in ['module://ipykernel.pylab.backend_inline',
Expand Down