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    "## Callisto tket framework\n",
    "\n",
    "The tket framework is a quantum software framework primarily used for the development and execution of quantum algorithms (quantum circuits). It is designed to be platform-agnostic software, and there are a lot of extensions available which allow tket to interface with backends from a range of providers ( see <a href=\"https://cqcl.github.io/pytket-extensions/api/index.html\"> tket extension </a> ).\n",
    "\n",
    "Due to its popularity and the broad amount of available backends using this framework, we wrote an extension to tket that enables a user to communicate with the C12 emulator <b> Callisto </b>. The backend name is `CallistoBackend`.\n",
    "\n",
    "We need to create a circuit using the `Circuit` class to run a quantum algorithm."
   ]
  },
  {
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   "execution_count": 1,
   "metadata": {
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    "ExecuteTime": {
     "end_time": "2024-10-08T14:54:52.019991Z",
     "start_time": "2024-10-08T14:54:51.906497Z"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[X q[0];, CX q[0], q[1];]\n"
     ]
    }
   ],
   "source": [
    "from pytket import Circuit\n",
    "\n",
    "circuit = Circuit(2)\n",
    "circuit.X(0)\n",
    "circuit.CX(0, 1)\n",
    "\n",
    "print(circuit.get_commands())"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Internally all circuits in the pytket framework are represented as directed acyclic graphs (DAG). Using ptyket util package it is possible to see the corresponding DAG of the chosen circuit."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "A classical model for quantum computing is a model where the main program is run on the host computer, which occasionally sends off jobs to the quantum computer and retrieves the results. A backend represents a connection to some instance, either quantum hardware or an emulator. It presents a uniform interface for submitting circuits to be processed and retrieving the results. The main goal of this approach is to promote the development of platform-independent software, helping the code that the developers write to be more future-proof.\n",
    "\n",
    "Using tket's abstract class, `Backend,` it is possible to set different characteristics of a device that it should represent. The main properties that a backend need to implement are:\n",
    "\n",
    "1. The restrictions that are specific to specific quantum devices. Different constraints are encoded using the predicates, which are essentially a boolean property of a circuit that must return True to run the circuit on the target machine.\n",
    "\n",
    "2. Sending a circuit to the target device and examining the results. This process can be accomplished by calling `Backend.process_circuit()` or `Backend.process_circuits()` methods. These methods will send a circuit for execution and return an instance of `ResultHandle` as a result of their execution. The `ResultHandle` is a unique identifier that can be used to retrieve the actual results once the job has finished.\n",
    "\n",
    "3. Retrieval of the results. Obtaining the results of a successfully run job\n",
    " is done using the `Backend.get_result()` method, which returns an instance of `BackendResult` class. The class `BackendResult` has methods that can be useful for obtaining different pieces of information about the job that has been run. These methods are:\n",
    "`get_state()` - get the state vector\n",
    "`get_shots()` - get the shots. The shots are returned as a 2D array of the result for each shot.\n",
    "`get_counts()` - get the counts (it is obtained from the shots directly)\n",
    "`get_density_matrix()` - get the density matrix of the job.\n",
    "\n",
    "\n",
    "To implement the C12 emulator Callisto, we have developed `CallistoBackend` class with all the above options incorporated."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "outputs": [],
   "source": [
    "import os\n",
    "os.environ[\"C12_TOKEN\"] =  \"08071c09-4131-4369-ae5d-76be96a8cd86\"\n",
    "os.environ[\"C12_HOST_URL\"]= \"api.dev-simulator.c12qe.net\""
   ],
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    "ExecuteTime": {
     "end_time": "2024-10-08T14:55:11.492912Z",
     "start_time": "2024-10-08T14:55:11.490014Z"
    }
   }
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "collapsed": false,
    "ExecuteTime": {
     "end_time": "2024-10-08T14:55:17.168060Z",
     "start_time": "2024-10-08T14:55:15.127487Z"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "('0b022428-9ae3-4190-9129-3f4743905208',)\n"
     ]
    }
   ],
   "source": [
    "import os\n",
    "from c12_callisto_clients.pytket.extensions.callisto import CallistoBackend\n",
    "\n",
    "access_token = os.getenv(\"C12_TOKEN\") # Token that is obtained for allowing the access to the system\n",
    "backend_name = \"c12sim-iswap\"\n",
    "\n",
    "# create callisto backend instance\n",
    "callisto = CallistoBackend(backend_name, token=access_token, verbose=False)\n",
    "\n",
    "# Get the ResultHandle instance\n",
    "handle = callisto.process_circuit(circuit, n_shots=1024)\n",
    "print(handle)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
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    "ExecuteTime": {
     "end_time": "2024-10-08T14:56:11.741719Z",
     "start_time": "2024-10-08T14:55:19.552613Z"
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   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "CircuitStatus(status=<StatusEnum.COMPLETED: 'Circuit has completed. Results are ready.'>, message='', error_detail=None, completed_time=None, queued_time=None, submitted_time=None, running_time=None, cancelled_time=None, error_time=None, queue_position=None)\n",
      "[[1 1]\n",
      " [1 1]\n",
      " [1 1]\n",
      " ...\n",
      " [1 1]\n",
      " [1 1]\n",
      " [1 1]]\n",
      "Counter({(np.uint8(1), np.uint8(1)): np.int64(1024)})\n"
     ]
    }
   ],
   "source": [
    "job_uuid = handle[0]\n",
    "\n",
    "# Get BackendResult instance\n",
    "job_result = callisto.get_result(handle)\n",
    "\n",
    "\n",
    "print(callisto.circuit_status(handle)) # Get the status of the circuit\n",
    "print(job_result.get_shots())\n",
    "print(job_result.get_counts())"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
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    "ExecuteTime": {
     "end_time": "2024-10-08T14:57:48.915299Z",
     "start_time": "2024-10-08T14:57:48.615372Z"
    }
   },
   "outputs": [
    {
     "ename": "CircuitNotValidError",
     "evalue": "Circuit with index 0 in submitted does not satisfy MaxNQubitsPredicate(13) (try compiling with backend.get_compiled_circuits first).",
     "output_type": "error",
     "traceback": [
      "\u001B[0;31m---------------------------------------------------------------------------\u001B[0m",
      "\u001B[0;31mCircuitNotValidError\u001B[0m                      Traceback (most recent call last)",
      "Cell \u001B[0;32mIn[5], line 6\u001B[0m\n\u001B[1;32m      3\u001B[0m     circuit2\u001B[38;5;241m.\u001B[39mX(n)\n\u001B[1;32m      4\u001B[0m     circuit2\u001B[38;5;241m.\u001B[39mCX(\u001B[38;5;241m0\u001B[39m, n)\n\u001B[0;32m----> 6\u001B[0m handle2 \u001B[38;5;241m=\u001B[39m \u001B[43mcallisto\u001B[49m\u001B[38;5;241;43m.\u001B[39;49m\u001B[43mprocess_circuit\u001B[49m\u001B[43m(\u001B[49m\u001B[43mcircuit2\u001B[49m\u001B[43m,\u001B[49m\u001B[43m \u001B[49m\u001B[43mn_shots\u001B[49m\u001B[38;5;241;43m=\u001B[39;49m\u001B[38;5;241;43m1024\u001B[39;49m\u001B[43m)\u001B[49m\n\u001B[1;32m      8\u001B[0m \u001B[38;5;66;03m# This should fail due to MaxNQubitsPredicate which controls the number of qubits that can be run on the emulator\u001B[39;00m\n",
      "File \u001B[0;32m~/Desktop/Projects/simulator/C12QEsimulator/src/c12_callisto_clients/pytket/extensions/callisto/backends/callisto.py:321\u001B[0m, in \u001B[0;36mCallistoBackend.process_circuit\u001B[0;34m(self, circuit, n_shots, valid_check, **kwargs)\u001B[0m\n\u001B[1;32m    317\u001B[0m \u001B[38;5;250m\u001B[39m\u001B[38;5;124;03m\"\"\"\u001B[39;00m\n\u001B[1;32m    318\u001B[0m \u001B[38;5;124;03mRun a single circuit.\u001B[39;00m\n\u001B[1;32m    319\u001B[0m \u001B[38;5;124;03m\"\"\"\u001B[39;00m\n\u001B[1;32m    320\u001B[0m \u001B[38;5;28;01mif\u001B[39;00m valid_check:\n\u001B[0;32m--> 321\u001B[0m     \u001B[38;5;28;43mself\u001B[39;49m\u001B[38;5;241;43m.\u001B[39;49m\u001B[43m_check_all_circuits\u001B[49m\u001B[43m(\u001B[49m\u001B[43m[\u001B[49m\u001B[43mcircuit\u001B[49m\u001B[43m]\u001B[49m\u001B[43m)\u001B[49m\n\u001B[1;32m    323\u001B[0m n_shots \u001B[38;5;241m=\u001B[39m \u001B[38;5;241m1024\u001B[39m \u001B[38;5;28;01mif\u001B[39;00m n_shots \u001B[38;5;129;01mis\u001B[39;00m \u001B[38;5;28;01mNone\u001B[39;00m \u001B[38;5;28;01melse\u001B[39;00m n_shots\n\u001B[1;32m    324\u001B[0m result_type \u001B[38;5;241m=\u001B[39m \u001B[38;5;124m\"\u001B[39m\u001B[38;5;124mcounts,statevector,density_matrix\u001B[39m\u001B[38;5;124m\"\u001B[39m\n",
      "File \u001B[0;32m/opt/anaconda3/envs/c12_callisto_clients/lib/python3.10/site-packages/pytket/backends/backend.py:126\u001B[0m, in \u001B[0;36mBackend._check_all_circuits\u001B[0;34m(self, circuits, nomeasure_warn)\u001B[0m\n\u001B[1;32m    120\u001B[0m errors \u001B[38;5;241m=\u001B[39m (\n\u001B[1;32m    121\u001B[0m     CircuitNotValidError(i, \u001B[38;5;28mrepr\u001B[39m(pred))\n\u001B[1;32m    122\u001B[0m     \u001B[38;5;28;01mfor\u001B[39;00m pred \u001B[38;5;129;01min\u001B[39;00m \u001B[38;5;28mself\u001B[39m\u001B[38;5;241m.\u001B[39mrequired_predicates\n\u001B[1;32m    123\u001B[0m     \u001B[38;5;28;01mif\u001B[39;00m \u001B[38;5;129;01mnot\u001B[39;00m pred\u001B[38;5;241m.\u001B[39mverify(circ)\n\u001B[1;32m    124\u001B[0m )\n\u001B[1;32m    125\u001B[0m \u001B[38;5;28;01mfor\u001B[39;00m error \u001B[38;5;129;01min\u001B[39;00m errors:\n\u001B[0;32m--> 126\u001B[0m     \u001B[38;5;28;01mraise\u001B[39;00m error\n\u001B[1;32m    127\u001B[0m \u001B[38;5;28;01mif\u001B[39;00m nomeasure_warn:\n\u001B[1;32m    128\u001B[0m     \u001B[38;5;28;01mif\u001B[39;00m circ\u001B[38;5;241m.\u001B[39mn_gates_of_type(OpType\u001B[38;5;241m.\u001B[39mMeasure) \u001B[38;5;241m<\u001B[39m \u001B[38;5;241m1\u001B[39m:\n",
      "\u001B[0;31mCircuitNotValidError\u001B[0m: Circuit with index 0 in submitted does not satisfy MaxNQubitsPredicate(13) (try compiling with backend.get_compiled_circuits first)."
     ]
    }
   ],
   "source": [
    "circuit2 = Circuit(20)\n",
    "for n in range(1, 20):\n",
    "    circuit2.X(n)\n",
    "    circuit2.CX(0, n)\n",
    "\n",
    "handle2 = callisto.process_circuit(circuit2, n_shots=1024)\n",
    "\n",
    "# This should fail due to MaxNQubitsPredicate which controls the number of qubits that can be run on the emulator"
   ]
  },
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