Add a tutorial and nbsphinx (#243)

Trying to reproduce
#221.

This is good for us to have either way. Related to
#220.

![Screenshot 2023-04-04 at 11 44 55
AM](https://user-images.githubusercontent.com/14852634/229874662-d9479b1f-e866-4597-82f6-e037d87ec519.png)

--

![Screenshot 2023-04-04 at 11 45 07
AM](https://user-images.githubusercontent.com/14852634/229874718-b3ab9a2a-af7d-42d5-a287-2aec7372e0cb.png)

docs/conf.py

@@ -71,6 +71,7 @@
     'sphinx.ext.extlinks',
     'jupyter_sphinx',
     'sphinx_design',
+    "nbsphinx",
 ]
 
 # -----------------------------------------------------------------------------
@@ -158,6 +159,16 @@
 }
 
 
+# -----------------------------------------------------------------------------
+# nbsphinx
+# -----------------------------------------------------------------------------
+
+nbsphinx_execute = "never"
+nbsphinx_thumbnails = {
+    "sphinx_guide/notebook": "_static/no_image.png",
+}
+
+
 # set up custom extension for languages
 def setup(app):
     app.setup_extension('language_utils')

docs/index.rst

@@ -25,4 +25,5 @@ Qiskit sphinx theme |version| documentation
    sphinx_guide/jupyter
    sphinx_guide/paragraph
    sphinx_guide/structural
+   sphinx_guide/notebook_gallery
    GitHub <https://github.com/Qiskit/qiskit-terra>

docs/sphinx_guide/notebook.ipynb

@@ -0,0 +1,45 @@
+{
+    "cells": [
+        {
+            "cell_type": "markdown",
+            "metadata": {},
+            "source": [
+                "# My tutorial with a long title"
+            ]
+        },
+        {
+            "cell_type": "markdown",
+            "metadata": {},
+            "source": [
+                "## Introduction \n",
+                "\n",
+                "The molecular Hamiltonian is \n",
+                "\n",
+                "$$\n",
+                "\\mathcal{H} = - \\sum_I \\frac{\\nabla_{R_I}^2}{M_I} - \\sum_i \\frac{\\nabla_{r_i}^2}{m_e} - \\sum_I\\sum_i  \\frac{Z_I e^2}{|R_I-r_i|} + \\sum_i \\sum_{j>i} \\frac{e^2}{|r_i-r_j|} + \\sum_I\\sum_{J>I} \\frac{Z_I Z_J e^2}{|R_I-R_J|}\n",
+                "$$\n"
+            ]
+        }
+    ],
+    "metadata": {
+        "kernelspec": {
+            "display_name": "Python 3",
+            "language": "python",
+            "name": "python3"
+        },
+        "language_info": {
+            "codemirror_mode": {
+                "name": "ipython",
+                "version": 3
+            },
+            "file_extension": ".py",
+            "mimetype": "text/x-python",
+            "name": "python",
+            "nbconvert_exporter": "python",
+            "pygments_lexer": "ipython3",
+            "version": "3.9.16"
+        }
+    },
+    "nbformat": 4,
+    "nbformat_minor": 4
+}

docs/sphinx_guide/notebook_gallery.rst

@@ -0,0 +1,7 @@
+#######################
+Tutorials
+#######################
+
+
+.. nbgallery::
+    notebook.ipynb

requirements-dev.txt

@@ -4,3 +4,4 @@ numpy
 matplotlib
 sphinx-design
 sphinx-autodoc-typehints
+nbsphinx==0.9.*