https://hfwang132.github.io/tags/%E9%87%8F%E5%AD%90%E7%BA%A0%E7%BC%A0/Recent content in 量子纠缠 on Haifei's HomeHugozh-CNhfwang132@gmail.com (hfwang132)hfwang132@gmail.com (hfwang132)This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.Sun, 30 Jul 2023 02:51:44 +0800https://hfwang132.github.io/post_20230730_%E8%BE%A8%E6%9E%90%E6%B7%B7%E5%90%88%E6%80%81%E4%B8%8E%E7%BA%A0%E7%BC%A0%E6%80%81/Sun, 30 Jul 2023 02:51:44 +0800hfwang132@gmail.com (hfwang132)https://hfwang132.github.io/post_20230730_%E8%BE%A8%E6%9E%90%E6%B7%B7%E5%90%88%E6%80%81%E4%B8%8E%E7%BA%A0%E7%BC%A0%E6%80%81/<h2 id="一纯态与混合态">一、纯态与混合态</h2> <p>要想搞明白纯态和混合态，首先就必须搞明白<strong>密度算子</strong>（density operator），或<strong>密度矩阵</strong>（density matrix）。</p> <h3 id="11密度算子是啥">1.1密度算子是啥？</h3> <p>当我第一次看到密度算子的时候，我觉得它非常神奇。因为它是将<strong>一个态与自己的对偶做张量积</strong>：</p>