UCC.ipynb

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       "<pre style=\"word-wrap: normal;white-space: pre;background: #fff0;line-height: 1.1;font-family: &quot;Courier New&quot;,Courier,monospace\">     ┌───┐┌────────────────────┐┌────────────────────┐┌────────────────────┐\n",
       "q_0: ┤ X ├┤0                   ├┤0                   ├┤0                   ├\n",
       "     └───┘│                    ││                    ││                    │\n",
       "q_1: ─────┤1                   ├┤1                   ├┤1                   ├\n",
       "          │  Evolution^1(x[0]) ││  Evolution^1(x[1]) ││  Evolution^1(x[2]) │\n",
       "q_2: ─────┤2                   ├┤2                   ├┤2                   ├\n",
       "          │                    ││                    ││                    │\n",
       "q_3: ─────┤3                   ├┤3                   ├┤3                   ├\n",
       "          └────────────────────┘└────────────────────┘└────────────────────┘</pre>"
      ],
      "text/plain": [
       "     ┌───┐┌────────────────────┐┌────────────────────┐┌────────────────────┐\n",
       "q_0: ┤ X ├┤0                   ├┤0                   ├┤0                   ├\n",
       "     └───┘│                    ││                    ││                    │\n",
       "q_1: ─────┤1                   ├┤1                   ├┤1                   ├\n",
       "          │  Evolution^1(x[0]) ││  Evolution^1(x[1]) ││  Evolution^1(x[2]) │\n",
       "q_2: ─────┤2                   ├┤2                   ├┤2                   ├\n",
       "          │                    ││                    ││                    │\n",
       "q_3: ─────┤3                   ├┤3                   ├┤3                   ├\n",
       "          └────────────────────┘└────────────────────┘└────────────────────┘"
      ]
     },
     "execution_count": 33,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "import numpy as np\n",
    "from qiskit.quantum_info import Statevector\n",
    "from qiskit.circuit import ParameterVector\n",
    "from qiskit.chemistry.components.variational_forms import UCCSD\n",
    "\n",
    "x = ParameterVector('x', 3)\n",
    "uvcc_varform = UCCSD(4, 2, qubit_mapping = 'jordan_wigner', two_qubit_reduction=False)\n",
    "circuit = QuantumCircuit(4)\n",
    "circuit.x(0)  # initial state\n",
    "circuit.compose(uvcc_varform.construct_circuit(x), inplace=True)  # add UCC ansatz\n",
    "circuit.draw()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 42,
   "metadata": {},
   "outputs": [],
   "source": [
    "# param shift rule\n",
    "finite_difference = True \n",
    "shift = 0.1\n",
    "gradient_circuits = {}\n",
    "point = {x_i: np.random.random(1)[0] for x_i in x}\n",
    "for x_i in x:\n",
    "    # shifted parameters\n",
    "    plus = circuit.bind_parameters({x_j: point_j + shift * int(x_i == x_j) for x_j, point_j in point.items()})\n",
    "    minus = circuit.bind_parameters({x_j: point_j - shift * int(x_i == x_j) for x_j, point_j in point.items()})\n",
    "    gradient_circuits[x_i] = (plus, minus)"
   ]
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   "execution_count": 44,
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     "text": [
      "x[0] [-0.  +0.j -0.02+0.j  1.  -0.j -0.  +0.j  0.  -0.j -0.  +0.j -0.  +0.j\n",
      " -0.  -0.j -0.  +0.j -0.  +0.j -0.  +0.j  0.  -0.j  0.  -0.j -0.  -0.j\n",
      "  0.  +0.j -0.  -0.j]\n",
      "x[1] [ 0.-0.j -0.-0.j  0.-0.j -0.+0.j  0.+0.j  0.-0.j  0.-0.j  0.+0.j -0.+0.j\n",
      " -0.+0.j -0.-0.j -0.+0.j -0.-0.j -0.+0.j  0.+0.j  0.+0.j]\n",
      "x[2] [-0.-0.j -0.+0.j -0.+0.j -0.+0.j -0.-0.j -0.-0.j  0.+0.j  0.+0.j -0.-0.j\n",
      "  0.+0.j -0.-0.j -0.+0.j  0.+0.j  0.-0.j  0.+0.j -0.+0.j]\n"
     ]
    }
   ],
   "source": [
    "for x_i, (plus, minus) in gradient_circuits.items():\n",
    "    # print(plus.draw())\n",
    "    # print(minus.draw())\n",
    "    difference = Statevector.from_instruction(plus) - Statevector.from_instruction(minus)\n",
    "    if finite_difference:\n",
    "        difference /= 2 * shift\n",
    "    print(x_i, np.round(difference.data, 2))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
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