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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Emulating custom hardware inside universal processors\n",
    "\n",
    "In order to correctly emulate the behavior of a software stack built on a specific hardware, one might need to force some simulator to publish some particular hardware specs.\n",
    "\n",
    "Lets say, for instance, that you want to particularize the `LinAlg` simulator in order for it to publish a limited connectivity, or a fixed number of qubits. Any plugin on top of this particularized `LinAlg` would see these constraints, and would act according to this information.\n",
    "\n",
    "This is exactly the purpose of the `Quameleon` Plugin.\n",
    "\n",
    "The following cell demonstrate the use of this Plugin to build a custom `LinAlg` instance that publish a limited number of qubits over a linear nearest neighbor connectivity."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from qat.core import HardwareSpecs, Topology, TopologyType\n",
    "from qat.core.quameleon import QuameleonPlugin\n",
    "from qat.qpus import get_default_qpu\n",
    "\n",
    "my_custom_specs = HardwareSpecs(nbqbits=12, topology=Topology(type=TopologyType.LNN))\n",
    "\n",
    "qpu = QuameleonPlugin(specs=my_custom_specs) | get_default_qpu()\n",
    "\n",
    "qpu_specs = qpu.get_specs()\n",
    "print(\"Default specs of LinAlg:\", get_default_qpu().get_specs())\n",
    "print(\"Our specs:\", qpu_specs)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "As you can see, this new QPU publishes exactly the specs we required, instead of publishing a trivial set of specs.\n",
    "\n",
    "Moreover, sending a circuit that is not compliant with these specs will raise an appropriate exception:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from qat.lang.AQASM import *\n",
    "\n",
    "prog = Program()\n",
    "qbits= prog.qalloc(3)\n",
    "prog.apply(CNOT, qbits[0], qbits[2])# This gate is not LNN\n",
    "job = prog.to_circ().to_job()\n",
    "try:\n",
    "    qpu.submit(job)\n",
    "except Exception as e:\n",
    "    print(e.message)\n",
    "    \n",
    "prog = Program()\n",
    "qbits= prog.qalloc(15)\n",
    "prog.apply(H, qbits[14])# This qubit is out of bound\n",
    "job = prog.to_circ().to_job()\n",
    "try:\n",
    "    qpu.submit(job)\n",
    "except Exception as e:\n",
    "    print(e.message)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Of course, we can do the same with custom topologies:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "my_topology = Topology(type=TopologyType.CUSTOM)\n",
    "my_topology.add_edge(0, 2)\n",
    "my_topology.add_edge(1, 2)\n",
    "my_topology.add_edge(3, 2)\n",
    "my_topology.add_edge(4, 2)\n",
    "my_topology.add_edge(0, 1)\n",
    "my_topology.add_edge(3, 4)\n",
    "\n",
    "my_ibm_qx4_specs = HardwareSpecs(nbqbits=5, topology=my_topology)\n",
    "\n",
    "qpu = QuameleonPlugin(specs=my_ibm_qx4_specs) | get_default_qpu()\n",
    "print(qpu.get_specs())"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "And also custom gate sets:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from qat.core.gate_set import GateSet\n",
    "\n",
    "gate_set = GateSet({\n",
    "    \"H\" : AbstractGate(\"H\", [], arity=1)\n",
    "})\n",
    "my_specs = HardwareSpecs(gateset=gate_set)\n",
    "\n",
    "\n",
    "qpu = QuameleonPlugin(specs=my_specs) | get_default_qpu()\n",
    "print(qpu.get_specs())\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# declaring a custom gate \"FOO\"\n",
    "FOO = AbstractGate(\"FOO\", [], arity=1)\n",
    "prog = Program()\n",
    "qbits= prog.qalloc(1)\n",
    "prog.apply(FOO(), qbits)\n",
    "job = prog.to_circ().to_job()\n",
    "try:\n",
    "    qpu.submit(job)\n",
    "except Exception as e:\n",
    "    print(e)\n",
    "# using only declared gates\n",
    "prog = Program()\n",
    "qbits= prog.qalloc(1)\n",
    "prog.apply(H, qbits)\n",
    "job = prog.to_circ().to_job()\n",
    "results = qpu.submit(job)\n",
    "print(\"Everything went fine.\")"
   ]
  }
 ],
 "metadata": {
  "authors": [
   "Simon Martiel"
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