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    "# Writing a basic quantum program\n",
    "\n",
    "In this notebook, you will learn how to write a quantum program in Python on the Quantum Learning Machine.\n",
    "\n",
    "\n",
    "In the QLM python framework, a quantum program is contained in a ``Program`` class. It comes with methods to allocate quantum and classical registers, apply gates, measures and resets. A given instance of a ``Program`` can then be converted to a quantum ``Circuit``, which is the object that can be fed to a quantum processor.\n",
    "\n",
    "### Initializaton of a Quantum Program\n",
    "\n",
    "In the following snippet, we instantiate a quantum program object called ``prog``:"
   ]
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   "source": [
    "from qat.lang.AQASM import Program\n",
    "\n",
    "prog = Program()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Quantum bit allocation\n",
    "\n",
    "The allocation of quantum bits is done via the ``qalloc`` method. It returns a register, which will then be used to refer to the qubits.\n",
    "\n",
    "In the following snippet, we allocated an 8-qubit register:"
   ]
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   "source": [
    "qbits = prog.qalloc(8)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Applying quantum gates\n",
    "\n",
    "The application of quantum gates is carried out through the ``apply`` method.\n",
    "\n",
    "Here, we apply standard Hadamard gate on qbit 0, a Pauli X gate on qubit 1, a CNOT gate on qubits 1 and 5, and a phase gate with angle $\\pi/6$ to qubit 5."
   ]
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   "source": [
    "from qat.lang.AQASM import H, X, CNOT, PH\n",
    "from math import pi\n",
    "\n",
    "prog.apply(H, qbits[0])\n",
    "prog.apply(X, qbits[1])\n",
    "prog.apply(CNOT, qbits[1], qbits[5])\n",
    "prog.apply(PH(pi/6), qbits[5])"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Generation of a quantum circuit\n",
    "\n",
    "Before we describe other common operations such as measurements, let us introduce the final step that allows to generate a quantum-simulation-ready quantum circuit out of the quantum program. \n",
    "\n",
    "This generation is done via the ``to_circ`` method: "
   ]
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   "outputs": [],
   "source": [
    "circ = prog.to_circ()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Circuit display\n",
    "The ``.display`` method outputs a graphical representation of the quantum circuit:"
   ]
  },
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   "outputs": [],
   "source": [
    "circ.display()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "For a more comprehensive reference on the Python AQASM library, including **measures, classical control, custom gates, etc.**, check out [this tutorial](py_aqasm.ipynb).\n",
    "You will find a list of all available gates [here](available_gates.ipynb)."
   ]
  },
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  "authors": [
   "Simon Martiel"
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