.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "gallery/ghz_with_tn.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        Click :ref:`here <sphx_glr_download_gallery_ghz_with_tn.py>`
        to download the full example code

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_gallery_ghz_with_tn.py:


Using Tensor Network simulator
==============================

In this example, we simulate a circuit to create Greenberger-Horne-Zeilinger(GHZ) state with a tensor network simulator.

We will simulate the generation of 100-qubit GHZ state.
Firstly, let us import relevant modules:

.. GENERATED FROM PYTHON SOURCE LINES 12-31

.. code-block:: default


    import matplotlib.pyplot as plt
    import networkx as nx

    from graphix import Circuit

    n = 100
    print(f"{n}-qubit GHZ state generation")
    circuit = Circuit(n)

    # initialize to ``|0>`` state.
    for i in range(n):
        circuit.h(i)

    # GHZ generation
    circuit.h(0)
    for i in range(1, n):
        circuit.cnot(i - 1, i)





.. rst-class:: sphx-glr-script-out

 .. code-block:: none

    100-qubit GHZ state generation




.. GENERATED FROM PYTHON SOURCE LINES 32-33

Transpile into pattern

.. GENERATED FROM PYTHON SOURCE LINES 33-47

.. code-block:: default


    pattern = circuit.transpile().pattern
    pattern.standardize()

    nodes, edges = pattern.get_graph()
    g = nx.Graph()
    g.add_nodes_from(nodes)
    g.add_edges_from(edges)
    print(f"Number of nodes: {len(nodes)}")
    print(f"Number of edges: {len(edges)}")
    pos = nx.spring_layout(g)
    nx.draw(g, pos=pos, node_size=15)
    plt.show()




.. image-sg:: /gallery/images/sphx_glr_ghz_with_tn_001.png
   :alt: ghz with tn
   :srcset: /gallery/images/sphx_glr_ghz_with_tn_001.png
   :class: sphx-glr-single-img


.. rst-class:: sphx-glr-script-out

 .. code-block:: none

    Number of nodes: 399
    Number of edges: 398




.. GENERATED FROM PYTHON SOURCE LINES 48-49

Calculate the amplitudes of ``|00...0>`` and ``|11...1>`` states.

.. GENERATED FROM PYTHON SOURCE LINES 49-54

.. code-block:: default


    tn = pattern.simulate_pattern(backend="tensornetwork")
    print(f"The amplitude of |00...0>: {tn.get_basis_amplitude(0)}")
    print(f"The amplitude of |11...1>: {tn.get_basis_amplitude(2**n - 1)}")





.. rst-class:: sphx-glr-script-out

 .. code-block:: none

    The amplitude of |00...0>: 0.49999999999999317
    The amplitude of |11...1>: 0.49999999999999317





.. rst-class:: sphx-glr-timing

   **Total running time of the script:** ( 0 minutes  7.466 seconds)


.. _sphx_glr_download_gallery_ghz_with_tn.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example


    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: ghz_with_tn.py <ghz_with_tn.py>`

    .. container:: sphx-glr-download sphx-glr-download-jupyter

      :download:`Download Jupyter notebook: ghz_with_tn.ipynb <ghz_with_tn.ipynb>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_