{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {
    "qat-category": "1-Circuit generation in Python",
    "qat-summary": "1-Creation of an EPR pair using two qubits"
   },
   "source": [
    "# Creation of an EPR pair using two qubits\n",
    "\n",
    "\n",
    "    \n",
    "Let us start with a simple circuit: the creation of an EPR pair using two qubits.\n",
    "    \n",
    "    \n",
    "First, we need to import relevant objects from the python AQASM module:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "execution": {
     "iopub.execute_input": "2022-11-05T19:41:48.632336Z",
     "iopub.status.busy": "2022-11-05T19:41:48.632040Z",
     "iopub.status.idle": "2022-11-05T19:41:48.763181Z",
     "shell.execute_reply": "2022-11-05T19:41:48.762470Z"
    }
   },
   "outputs": [],
   "source": [
    "from qat.lang.AQASM import Program, H, CNOT "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Creation of the quantum program\n",
    "\n",
    "Then, we can declare a new object ``Program``. Let us give it an explicit name:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "execution": {
     "iopub.execute_input": "2022-11-05T19:41:48.767071Z",
     "iopub.status.busy": "2022-11-05T19:41:48.766669Z",
     "iopub.status.idle": "2022-11-05T19:41:48.769921Z",
     "shell.execute_reply": "2022-11-05T19:41:48.769313Z"
    }
   },
   "outputs": [],
   "source": [
    "epr_prog = Program() "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "To create our EPR pair, we need to manipulate two qbits. \n",
    "Qbits are manipulated through qbit registers only (to keep things structured).\n",
    "Registers are allocated as follows:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "execution": {
     "iopub.execute_input": "2022-11-05T19:41:48.772798Z",
     "iopub.status.busy": "2022-11-05T19:41:48.772534Z",
     "iopub.status.idle": "2022-11-05T19:41:48.775649Z",
     "shell.execute_reply": "2022-11-05T19:41:48.775081Z"
    }
   },
   "outputs": [],
   "source": [
    "qbits = epr_prog.qalloc(2) "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Now, we can access our qbits using the register \"qbits\".\n",
    "\n",
    "Registers behave like python list/arrays.\n",
    "\n",
    "Here our qbits will be refered to using qbits[0] and qbits[1].\n",
    "\n",
    "To create our EPR pair, we simply implement the appropriate 2-qbit rotation using a Hadamard gate (H) on the first qbit, followed by a controlled NOT gate (CNOT) on both qbits:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "execution": {
     "iopub.execute_input": "2022-11-05T19:41:48.778271Z",
     "iopub.status.busy": "2022-11-05T19:41:48.777950Z",
     "iopub.status.idle": "2022-11-05T19:41:48.780919Z",
     "shell.execute_reply": "2022-11-05T19:41:48.780351Z"
    }
   },
   "outputs": [],
   "source": [
    "epr_prog.apply(H, qbits[0]) \n",
    "epr_prog.apply(CNOT, qbits)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Notice that since the CNOT is applied on both qbits (it is a 2-qbit gate), we can pass the whole register as argument to the ``.apply`` method."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The corresponding circuit object can be extracted directly from the Program object as follows:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "execution": {
     "iopub.execute_input": "2022-11-05T19:41:48.783686Z",
     "iopub.status.busy": "2022-11-05T19:41:48.783442Z",
     "iopub.status.idle": "2022-11-05T19:41:49.085477Z",
     "shell.execute_reply": "2022-11-05T19:41:49.084721Z"
    }
   },
   "outputs": [],
   "source": [
    "circuit = epr_prog.to_circ()\n",
    "circuit.display()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Simulation of the execution of the circuit\n",
    "Now that we have a proper circuit, we can try and simulate it:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "execution": {
     "iopub.execute_input": "2022-11-05T19:41:49.124025Z",
     "iopub.status.busy": "2022-11-05T19:41:49.123578Z",
     "iopub.status.idle": "2022-11-05T19:41:49.140931Z",
     "shell.execute_reply": "2022-11-05T19:41:49.140242Z"
    }
   },
   "outputs": [],
   "source": [
    "#Let us import some qpu connected to a classical linear algebra simulator\n",
    "from qat.qpus import PyLinalg\n",
    "qpu = PyLinalg()\n",
    "\n",
    "job = circuit.to_job()\n",
    "\n",
    "result = qpu.submit(job)\n",
    "for sample in result:\n",
    "    print(\"State\", sample.state, \"with amplitude\", sample.amplitude)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Export to Atos Quantum Assembly Language (AQASM) format\n",
    "We can also export our circuit in the AQASM format:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "execution": {
     "iopub.execute_input": "2022-11-05T19:41:49.143796Z",
     "iopub.status.busy": "2022-11-05T19:41:49.143544Z",
     "iopub.status.idle": "2022-11-05T19:41:49.147902Z",
     "shell.execute_reply": "2022-11-05T19:41:49.147312Z"
    }
   },
   "outputs": [],
   "source": [
    "epr_prog.export(\"helloworld.aqasm\") "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The generated file *helloworld.aqasm* should look like this:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "execution": {
     "iopub.execute_input": "2022-11-05T19:41:49.150529Z",
     "iopub.status.busy": "2022-11-05T19:41:49.150282Z",
     "iopub.status.idle": "2022-11-05T19:41:49.423359Z",
     "shell.execute_reply": "2022-11-05T19:41:49.422530Z"
    }
   },
   "outputs": [],
   "source": [
    "!cat helloworld.aqasm"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "and can be compiled to circ format as follows:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "execution": {
     "iopub.execute_input": "2022-11-05T19:41:49.426835Z",
     "iopub.status.busy": "2022-11-05T19:41:49.426523Z",
     "iopub.status.idle": "2022-11-05T19:41:49.921905Z",
     "shell.execute_reply": "2022-11-05T19:41:49.921010Z"
    }
   },
   "outputs": [],
   "source": [
    "!aqasm2circ helloworld.aqasm"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
 "metadata": {
  "authors": [
   "Simon Martiel"
  ],
  "kernelspec": {
   "display_name": "Python 3 (ipykernel)",
   "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": "3.10.4"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 1
}