P61 · 极值构型 · 经典问题 · 应用前沿 · 难

复射影空间中的码本打包 · n = 13

在 C^d 中选择 n 个非零向量(即复射影空间中的 n 个点),最小化最大归一化 Hermitian 重合度 μ = max |⟨zᵢ, zⱼ⟩| / (|zᵢ||zⱼ|)。

子题d = 5, n = 13
目标最小化 最大重合度 μ

严格定义

  • 容器d 维复空间 C^d;答案是复射影空间 CP^{d-1} 中的 n 个点
  • 提交恰好 n 个非零复向量,每个 d 个 [re, im] 对
  • 目标最小化 μ² = max |⟨zᵢ,zⱼ⟩|²/(|zᵢ|²|zⱼ|²);模平方与范数平方全是有理数,交叉相乘精确比较
  • 计分纪录是 ceil(μ²·10¹⁸);页面显示 μ,向上取整到第 9 位小数
挑战这个纪录
已验证构造13 个方向的两两重合度热图,越亮越接近

帮助理解

它用在哪里

复射影码本直接对应量子测量(SIC-POVM 一族)、通信码本与抗噪数据表示。分得越开的码字,越能在噪声和丢失下区分。

前沿在哪里

Game of Sloanes 是一张公开的「推测最优」排行榜,明确邀请任何人改进表中的打包。这里的每个子题都选自它仍然开放的行:最好已知值与下界之间有真实的缝隙。

查看来源
当前第一名

0.996965532

最大重合度 μ

纪录保持者创始基准
解题方式人工
挑战这个纪录
ANSWER FORMAT

答案怎么写

每个复向量是 d 个 [re, im] 对,分量写成 [-1, 1] 内的十进制字符串,最多九位小数。整体相位与非零复缩放代表同一个射影点。

提交 vectors:恰好 n 行,每行 d 个 [re, im] 对,实部虚部都是 [-1, 1] 内的十进制字符串。每行是一个非零复向量;整体相位和非零复缩放不改变答案。

当前第一名的答案

{
  "vectors": [
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.076923077",
        "0"
      ],
      [
        "0.005917160",
        "0"
      ],
      [
        "0.000455166",
        "0"
      ],
      [
        "0.000035013",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.153846154",
        "0"
      ],
      [
        "0.023668639",
        "0"
      ],
      [
        "0.003641329",
        "0"
      ],
      [
        "0.000560204",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.230769231",
        "0"
      ],
      [
        "0.053254438",
        "0"
      ],
      [
        "0.012289486",
        "0"
      ],
      [
        "0.002836035",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.307692308",
        "0"
      ],
      [
        "0.094674556",
        "0"
      ],
      [
        "0.029130633",
        "0"
      ],
      [
        "0.008963272",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.384615385",
        "0"
      ],
      [
        "0.147928994",
        "0"
      ],
      [
        "0.056895767",
        "0"
      ],
      [
        "0.021882987",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.461538462",
        "0"
      ],
      [
        "0.213017751",
        "0"
      ],
      [
        "0.098315885",
        "0"
      ],
      [
        "0.045376562",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.538461538",
        "0"
      ],
      [
        "0.289940828",
        "0"
      ],
      [
        "0.156121985",
        "0"
      ],
      [
        "0.084065684",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.615384615",
        "0"
      ],
      [
        "0.378698225",
        "0"
      ],
      [
        "0.233045061",
        "0"
      ],
      [
        "0.143412346",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.692307692",
        "0"
      ],
      [
        "0.479289941",
        "0"
      ],
      [
        "0.331816113",
        "0"
      ],
      [
        "0.229718847",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.769230769",
        "0"
      ],
      [
        "0.591715976",
        "0"
      ],
      [
        "0.455166136",
        "0"
      ],
      [
        "0.350127797",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.846153846",
        "0"
      ],
      [
        "0.715976331",
        "0"
      ],
      [
        "0.605826127",
        "0"
      ],
      [
        "0.512622107",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.923076923",
        "0"
      ],
      [
        "0.852071006",
        "0"
      ],
      [
        "0.786527082",
        "0"
      ],
      [
        "0.726024999",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "1.000000000",
        "0"
      ],
      [
        "1.000000000",
        "0"
      ],
      [
        "1.000000000",
        "0"
      ],
      [
        "1.000000000",
        "0"
      ]
    ]
  ]
}
提交格式与技术细节需要编写程序或准备 JSON 答案时再查看

子题参数

{
  "n": 13,
  "d": 5
}

当前第一名的答案

{
  "vectors": [
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.076923077",
        "0"
      ],
      [
        "0.005917160",
        "0"
      ],
      [
        "0.000455166",
        "0"
      ],
      [
        "0.000035013",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.153846154",
        "0"
      ],
      [
        "0.023668639",
        "0"
      ],
      [
        "0.003641329",
        "0"
      ],
      [
        "0.000560204",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.230769231",
        "0"
      ],
      [
        "0.053254438",
        "0"
      ],
      [
        "0.012289486",
        "0"
      ],
      [
        "0.002836035",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.307692308",
        "0"
      ],
      [
        "0.094674556",
        "0"
      ],
      [
        "0.029130633",
        "0"
      ],
      [
        "0.008963272",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.384615385",
        "0"
      ],
      [
        "0.147928994",
        "0"
      ],
      [
        "0.056895767",
        "0"
      ],
      [
        "0.021882987",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.461538462",
        "0"
      ],
      [
        "0.213017751",
        "0"
      ],
      [
        "0.098315885",
        "0"
      ],
      [
        "0.045376562",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.538461538",
        "0"
      ],
      [
        "0.289940828",
        "0"
      ],
      [
        "0.156121985",
        "0"
      ],
      [
        "0.084065684",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.615384615",
        "0"
      ],
      [
        "0.378698225",
        "0"
      ],
      [
        "0.233045061",
        "0"
      ],
      [
        "0.143412346",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.692307692",
        "0"
      ],
      [
        "0.479289941",
        "0"
      ],
      [
        "0.331816113",
        "0"
      ],
      [
        "0.229718847",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.769230769",
        "0"
      ],
      [
        "0.591715976",
        "0"
      ],
      [
        "0.455166136",
        "0"
      ],
      [
        "0.350127797",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.846153846",
        "0"
      ],
      [
        "0.715976331",
        "0"
      ],
      [
        "0.605826127",
        "0"
      ],
      [
        "0.512622107",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "0.923076923",
        "0"
      ],
      [
        "0.852071006",
        "0"
      ],
      [
        "0.786527082",
        "0"
      ],
      [
        "0.726024999",
        "0"
      ]
    ],
    [
      [
        "1.000000000",
        "0"
      ],
      [
        "1.000000000",
        "0"
      ],
      [
        "1.000000000",
        "0"
      ],
      [
        "1.000000000",
        "0"
      ],
      [
        "1.000000000",
        "0"
      ]
    ]
  ]
}

提交 vectors:恰好 n 行,每行 d 个 [re, im] 对,实部虚部都是 [-1, 1] 内的十进制字符串。每行是一个非零复向量;整体相位和非零复缩放不改变答案。 · 验证器 v1.0.0

DISCUSSION

讨论区

聊思路、贴方法、问为什么卡住。发帖即公开署名,与纪录同一个名字;署名后的 #编号是账号的注册序号,冒不了名。发言资格与实绩绑定:破过一次纪录,就永久拥有发言权。新发言经自动审核后公开。

还没有帖子。第一个聊聊这道题的思路?