{
  "annotation_id": "b790c3f4-528e-466f-afb3-9e5fed1b4564",
  "date_created": "2026-03-02T18:01:39.264000Z",
  "date_modified": "2026-03-02T18:01:39.264000Z",
  "file_hash": "441ffe5b731769b81ea7ab72b086d9b94eff1413098b01366f4d98d5e25b9e3c",
  "private": false,
  "record": {
    "abstract": "Control over spin dynamics has been obtained in NMR via coherent averaging,\nwhich is implemented through a sequence of RF pulses, and via quantum codes\nwhich can protect against incoherent evolution. Here, we discuss the design and\nimplementation of quantum codes to protect against coherent evolution. A\ndetailed example is given of a quantum code for protecting two data qubits from\nevolution under a weak coupling (Ising) term in the Hamiltonian, using an\n``isolated\u0027\u0027 ancilla which does not evolve on the experimental time scale. The\ncode is realized in a three-spin system by liquid-state NMR spectroscopy on\n13C-labelled alanine, and tested for two initial states. It is also shown that\nfor coherent evolution and isolated ancillae, codes exist that do not require\nthe ancillae to initially be in a (pseudo-)pure state. Finally, it is shown\nthat even with non-isolated ancillae quantum codes exist which can protect\nagainst evolution under weak coupling. An example is presented for a six qubit\ncode that protects two data spins to first order.",
    "arxiv_id": "quant-ph/0004029",
    "authors": [
      "Yehuda Sharf",
      "Timothy F. Havel",
      "David G. Cory"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1063/1.1326071",
    "title": "Quantum Codes for Controlling Coherent Evolution",
    "url": "https://arxiv.org/abs/quant-ph/0004029"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "9e4ccc26-8ac5-4c56-9a9b-c4525a469ef0",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}