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File:Cat-state-even-loss-animation.gif

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Cat-state-even-loss-animation.gif (220 × 128 pixels, file size: 217 KB, MIME type: image/gif, looped, 40 frames, 5.0 s)

Summary

Description
English: Animated Wigner function of an even cat state. The animation shows the distribution for different values of the amplitude α and relative fractional loss.
Date
Source Own work
Author Geek3
GIF development
InfoField
 
This plot was created with Matplotlib.
Source code
InfoField

Python code

#!/usr/bin/python
# -*- coding: utf8 -*-

import numpy as np
from math import *
import matplotlib.pyplot as plt
from matplotlib import animation, ticker
import os

# settings
plt.rc('path', snap=False)
plt.rc('mathtext', default='regular')
fname = 'Cat-state-even-loss-animation'
width, height = 220, 128
dpi = 65.
nframes = 40
fps = 10
alpha0 = 2.
xlim = -4, 4
ylim = -2, 2
res = 40.

x_range = np.linspace(xlim[0], xlim[1], res*4+1)
y_range = np.linspace(ylim[0], ylim[1], res*2+1)
x_pixels = (x_range[1:] + x_range[:-1]) / 2.
y_pixels = (y_range[1:] + y_range[:-1]) / 2.
X, Y = np.meshgrid(x_pixels, y_pixels)

delays = [100 // fps for i in range(nframes)]
delays[0] = delays[20] = 60

plt.close('all')

def cat_state(x, y, alpha, theta, L):
    # Eq. (64), Phys. Rev. A 80, 032318 (2009)
    gaussm = np.exp(-(x + sqrt(2 * (1-L)) * alpha)**2 - y**2)
    gaussp = np.exp(-(x - sqrt(2 * (1-L)) * alpha)**2 - y**2)
    gauss0 = np.exp(-x**2 - y**2)
    fringe = np.cos(sqrt(8 * (1-L)) * alpha * y + theta)
    damp = exp(-2 * L * alpha**2)
    norm = 2 * pi * (1. + exp(-2 * alpha**2) * cos(theta))
    return (gaussm + gaussp + 2. * gauss0 * fringe * damp) / norm

def animate(nframe):
    print 'frame', nframe+1, '/', nframes
    t = nframe / float(nframes)
    plt.clf()
    
    if t < 0.5:
        alpha = alpha0
        L = t / 0.5
    else:
        alpha = alpha0 * (t - 0.5) / 0.5
        L = 0.
    
    img = cat_state(X, Y, alpha, 0., L)
    plt.imshow(img, cmap='RdBu', vmin=-1/pi, vmax=1/pi, origin='lower',
        extent=(xlim[0], xlim[1], ylim[0], ylim[1]))
    
    plt.title(r'$\alpha={:.1f}$   loss$={:.2f}$'.format(alpha, L))
    plt.gca().set_aspect('equal', adjustable='box')
    plt.gca().yaxis.set_major_locator(ticker.MultipleLocator(1))
    plt.subplots_adjust(left=0.1, right=1-0.06, bottom=0.1)

fig = plt.figure(figsize=(width/float(dpi), height/float(dpi)))

# start animation
if 0 != os.system('convert -version > ' +  os.devnull):
    print 'imagemagick not installed!'
    # warning: imagemagick produces dithered and therefore large gifs
    anim = animation.FuncAnimation(fig, animate, frames=nframes)
    anim.save(fname + '.gif', writer='imagemagick', fps=fps, dpi=dpi)
else:
    # unfortunately the matplotlib imagemagick backend does not support
    # options which are necessary to generate high quality output without
    # framewise color palettes. Therefore save all frames and convert then.
    if not os.path.isdir(fname):
        os.mkdir(fname)
    fnames = []
    
    for frame in range(nframes):
        animate(frame)
        imgname = os.path.join(fname, fname + '{:03d}'.format(frame) + '.png')
        fig.savefig(imgname, dpi=dpi)
        fnames.append(imgname)
    
    # compile optimized animation with ImageMagick
    cmd = 'convert -loop 0 '
    nameslist = ['-delay ' + str(delays[i]) + ' ' + n for i,n in enumerate(fnames)]
    cmd += ' '.join(nameslist)
    cmd += ' +dither -colors 255 '
    cmd += fname + '.gif'
    os.system(cmd)
    
    for fnamei in fnames:
        os.remove(fnamei)
    os.rmdir(fname)

Licensing

I, the copyright holder of this work, hereby publish it under the following license:
w:en:Creative Commons
attribution share alike
This file is licensed under the Creative Commons Attribution-Share Alike 4.0 International license.
You are free:
  • to share – to copy, distribute and transmit the work
  • to remix – to adapt the work
Under the following conditions:
  • attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
  • share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.

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1 September 2018

image/gif

10d8e924308168223f271146f734019be12de1ea

222,375 byte

4.999999999999998 second

128 pixel

220 pixel

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Date/TimeThumbnailDimensionsUserComment
current20:12, 1 September 2018Thumbnail for version as of 20:12, 1 September 2018220 × 128 (217 KB)Geek3User created page with UploadWizard

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