{
  "annotation_id": "065596f8-ce17-4014-be13-1bf9b434ad63",
  "date_created": "2026-03-02T18:02:48.523000Z",
  "date_modified": "2026-03-02T18:02:48.523000Z",
  "file_hash": "4b9ad05a307e038e4f673ad4f17dfdef83c48a4aebd1fa47990582becb4b86b5",
  "private": false,
  "record": {
    "abstract": "We present an efficient scheme which couples any designated pair of spins in\nheteronuclear spin systems. The scheme is based on the existence of Hadamard\nmatrices. For a system of $n$ spins with pairwise coupling, the scheme\nconcatenates $cn$ intervals of system evolution and uses at most $c n^2$ pulses\nwhere $c \\approx 1$. Our results demonstrate that, in many systems, selective\nrecoupling is possible with linear overhead, contrary to common speculation\nthat exponential effort is always required.",
    "arxiv_id": "quant-ph/9904100",
    "authors": [
      "Debbie W. Leung",
      "Isaac L. Chuang",
      "Fumiko Yamaguchi",
      "Yoshihisa Yamamoto"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1103/PhysRevA.61.042310",
    "journal_ref": "Phys.Rev.A61:042310,2000",
    "title": "Efficient implementation of selective recoupling in heteronuclear spin   systems using Hadamard matrices",
    "url": "https://arxiv.org/abs/quant-ph/9904100"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "378fe7a4-6877-4403-bd5b-a841edc436fe",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}