File:Wigner quasiprobability distribution of cat states, grid.webm
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Summary
{{Information
|description=
English: Wigner quasiprobability distribution of cat states, grid. Cat states with 2, 3, 4 cats. The separation between cats range from 0.5, 1, 2, 3, showing increasingly sharp inference.
Matplotlib code
import matplotlib.pyplot as plt
import matplotlib as mpl
import numpy as np
from IPython.display import display
from qutip import (about, basis, coherent, coherent_dm, displace, fock, ket2dm,
plot_wigner, squeeze, thermal_dm, wigner_cmap, wigner)
import scipy.ndimage
import os
from tqdm import tqdm
def rotate_and_crop(array, angle, xvec, yvec):
rotated_array = scipy.ndimage.rotate(array, -angle, reshape=False)
rows, cols = rotated_array.shape
center_row, center_col = rows // 2, cols // 2
target_rows, target_cols = len(yvec), len(xvec)
start_row = center_row - target_rows // 2
end_row = start_row + target_rows
start_col = center_col - target_cols // 2
end_col = start_col + target_cols
return rotated_array[start_row:end_row, start_col:end_col]
def plot_wigner_marginals(W, xvec, yvec, marginal_max, resolution=200, angle=0):
wmap = wigner_cmap(W)
wlim = np.abs(W).max()
cmap = plt.colormaps['RdBu']
fig = plt.figure()
n, m = 5, 1
fig, axes = plt.subplot_mosaic(
[ ["top"] * n + ["3d"] * m ] * m + [ ["mid"] * n + ["right"] * m] * n,
figsize=(20, 20),
layout="constrained",
width_ratios=[1.05] * (n+m))
ax = axes["mid"]
norm = mpl.colors.Normalize(-wlim, wlim)
ax.contourf(xvec, yvec, W, resolution // 3, norm=norm, cmap=cmap)
ax = axes["top"]
x_marginal = np.sum(W, axis=0)
y_marginal = np.sum(W, axis=1)
ax.fill_between(xvec, x_marginal, 0, color='#938fba', alpha=0.5)
ax.plot(xvec, x_marginal, color='#4a5a90')
ax.set_xlim(min(xvec), max(xvec))
ax.set_ylim(0, marginal_max * 1.05)
ax.set_xticks([])
ax.set_yticks([])
ax = axes["right"]
ax.fill_betweenx(yvec, np.sum(W, axis=1), 0, color='#938fba', alpha=0.5)
ax.plot(y_marginal, yvec, color='#4a5a90')
ax.set_xlim(0, marginal_max * 1.05)
ax.set_ylim(min(yvec), max(yvec))
ax.set_xticks([])
ax.set_yticks([])
ax = axes["3d"]
ax.axis('off')
return fig
def plot_wigner_with_marginals(psi, **kwargs):
radius = kwargs.get('radius', 5)
resolution = kwargs.get('resolution', 500)
angles = kwargs.get('angles', np.linspace(0, 2*np.pi, 100))
dir_path = kwargs.get('dir_path', './output')
xvec_upscaled = np.linspace(-radius*1.5, radius*1.5, int(resolution*1.5))
yvec_upscaled = np.linspace(-radius*1.5, radius*1.5, int(resolution*1.5))
xvec = np.linspace(-radius, radius, int(resolution))
yvec = np.linspace(-radius, radius, int(resolution))
W_upscaled = wigner(psi, xvec_upscaled, yvec_upscaled)
marginal_max = max(max(np.sum(W_upscaled, axis=0)), max(np.sum(W_upscaled, axis=1)))
print(f"outputting to {dir_path}")
for N, angle in tqdm(enumerate(angles)):
W = rotate_and_crop(W_upscaled, angle, xvec, yvec)
fig = plot_wigner_marginals(W, xvec, yvec, marginal_max=marginal_max, resolution=resolution, angle=angle)
if not os.path.exists(dir_path):
os.makedirs(dir_path)
fig.savefig(f"{dir_path}/{N:03d}.png",bbox_inches='tight')
plt.close(fig)
mpl.use('agg')
configs = {
"N_dim" : 20,
"radius" : 4.5,
"resolution" : 600,
"angles" : range(360),
"dir_path" : ""
}
for separation in [0.5, 1, 2, 3]:
for cat_number in [2, 3, 4]:
psi = sum(
[coherent(configs["N_dim"], separation * np.exp(2j * np.pi * m / cat_number))
for m in range(cat_number)]
).unit()
configs["dir_path"] = f"./cat/cat_{cat_number}_{separation:.1f}"
plot_wigner_with_marginals(psi, **configs)
Sh code
for dir in ./*/; do
# Extract folder name
folder_name=$(basename "$dir")
# Create output path
output_path="./${folder_name}.webm"
# Convert images to webm
echo $output_path
# ffmpeg -y -framerate 24 -i "$dir"%03d.png -c:v libvpx-vp9 -b:v 0 -crf 30 -pix_fmt yuva420p "$output_path"
done
ffmpeg -y \
-i ./cat_2_0.5.webm \
-i ./cat_2_1.0.webm \
-i ./cat_2_2.0.webm \
-i ./cat_2_3.0.webm \
-i ./cat_3_0.5.webm \
-i ./cat_3_1.0.webm \
-i ./cat_3_2.0.webm \
-i ./cat_3_3.0.webm \
-i ./cat_4_0.5.webm \
-i ./cat_4_1.0.webm \
-i ./cat_4_2.0.webm \
-i ./cat_4_3.0.webm \
-filter_complex "
[0:v]scale=800:800[v0];
[1:v]scale=800:800[v1];
[2:v]scale=800:800[v2];
[3:v]scale=800:800[v3];
[4:v]scale=800:800[v4];
[5:v]scale=800:800[v5];
[6:v]scale=800:800[v6];
[7:v]scale=800:800[v7];
[8:v]scale=800:800[v8];
[9:v]scale=800:800[v9];
[10:v]scale=800:800[v10];
[11:v]scale=800:800[v11];
[v0][v1][v2][v3]hstack=inputs=4[row0];
[v4][v5][v6][v7]hstack=inputs=4[row1];
[v8][v9][v10][v11]hstack=inputs=4[row2];
[row0][row1][row2]vstack=inputs=3[out]
" \
-map "[out]" \
-c:v libvpx-vp9 -b:v 0 -crf 30 -pix_fmt yuva420p \
output_grid.webm
Licensing
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current | 05:01, 31 August 2024 | ![]() | (2.23 MB) | wikimediacommons>Cosmia Nebula | higher resolution |
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