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    "# 08 - Quantum Teleportation\n",
    "\n",
    "Transfer a quantum state from one qubit to another using entanglement.\n",
    "\n",
    "**Concepts:** Bell pair, Bell measurement, classical communication"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "e21b99b9",
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   "source": [
    "import quantsdk as qs\n",
    "import math"
   ]
  },
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   "source": [
    "## The Protocol\n",
    "\n",
    "1. Alice has state |psi> on qubit 0\n",
    "2. Alice and Bob share a Bell pair (qubits 1-2)\n",
    "3. Alice performs Bell measurement (qubits 0-1)\n",
    "4. Bob applies corrections based on Alice's results\n",
    "\n",
    "```\n",
    "q0 (Alice's state):  --[Rx]--*--[H]--[M]--\n",
    "q1 (Alice's Bell):   --[H]--*--[X]---[M]--\n",
    "q2 (Bob's Bell):     -------X-----------[M]\n",
    "```"
   ]
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   "cell_type": "code",
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   "source": [
    "def teleportation_circuit(theta: float) -> qs.Circuit:\n",
    "    \"\"\"Create teleportation circuit for state RY(theta)|0>.\"\"\"\n",
    "    circuit = qs.Circuit(3, name=f\"teleport-{theta:.2f}\")\n",
    "    \n",
    "    # Prepare state to teleport\n",
    "    circuit.ry(0, theta)\n",
    "    \n",
    "    # Create Bell pair (qubits 1-2)\n",
    "    circuit.barrier()\n",
    "    circuit.h(1).cx(1, 2)\n",
    "    \n",
    "    # Bell measurement\n",
    "    circuit.barrier()\n",
    "    circuit.cx(0, 1).h(0)\n",
    "    \n",
    "    # Measure all\n",
    "    circuit.measure_all()\n",
    "    return circuit"
   ]
  },
  {
   "cell_type": "code",
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   "source": [
    "# Teleport different states\n",
    "for theta in [0, math.pi/4, math.pi/2, math.pi]:\n",
    "    circuit = teleportation_circuit(theta)\n",
    "    result = qs.run(circuit, shots=2000, seed=42)\n",
    "    \n",
    "    # Analyze Bob's qubit (q2) conditioned on Alice's results\n",
    "    p_bob_1 = 0\n",
    "    for bitstring, count in result.counts.items():\n",
    "        if bitstring[2] == '1':  # Bob's qubit\n",
    "            p_bob_1 += count\n",
    "    p_bob_1 /= 2000\n",
    "    \n",
    "    expected = math.sin(theta / 2) ** 2\n",
    "    print(f\"theta={theta:.2f}: P(Bob=1)={p_bob_1:.3f} (need corrections, expected~{expected:.3f})\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "46633c18",
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   "source": [
    "# Show full output for one case\n",
    "circuit = teleportation_circuit(math.pi / 3)\n",
    "result = qs.run(circuit, shots=4000, seed=42)\n",
    "\n",
    "print(f\"Circuit depth: {circuit.depth}\")\n",
    "print(f\"Gate count: {circuit.gate_count}\")\n",
    "print(f\"\\nAll outcomes (q0 q1 q2):\")\n",
    "for bs, count in sorted(result.counts.items()):\n",
    "    print(f\"  |{bs}>: {count} ({count/4000:.3f})\")"
   ]
  }
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