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"# QuTiP lecture: Correlation functions \n",
"\n",
"Author: J. R. Johansson (robert@riken.jp), http://dml.riken.jp/~rob/\n",
"\n",
"The latest version of this [IPython notebook](http://ipython.org/ipython-doc/dev/interactive/htmlnotebook.html) lecture is available at [http://github.com/jrjohansson/qutip-lectures](http://github.com/jrjohansson/qutip-lectures).\n",
"\n",
"The other notebooks in this lecture series are indexed at [http://jrjohansson.github.com](http://jrjohansson.github.com)."
]
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"input": [
"%matplotlib inline\n",
"import matplotlib.pyplot as plt\n",
"import numpy as np"
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"cell_type": "code",
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"input": [
"from qutip import *"
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"## First-order coherence function\n",
"\n",
"\n",
"Consider an oscillator that is interacting with a thermal environment. If the oscillator initially is in a coherent state, it will gradually decay to a thermal (incoherent) state. The amount of coherence can be quantified using the first-order optical coherence function\n",
"\n",
"
\n",
"\n",
"If $Q$ is at a steady state at the initial time of measurement, we can set $\\tau = t_1 = t_2$ and the Leggett-Garg inequality then reads\n",
"\n",
"