We show – both theoretically and experimentally – that Einstein-Podolsky-Rosen steering can be distilled. We present a distillation protocol that outputs a perfectly correlated system – the singlet assemblage – in the asymptotic infinite-copy limit, even for inputs that are arbitrarily close to being unsteerable. As figures of merit for the protocol’s performance, we introduce the assemblage fidelity and the singlet-assemblage fraction. These are potentially interesting quantities on their own beyond the current scope. Remarkably, the protocol works well also in the non-asymptotic regime of few copies, in the sense of increasing the singlet-assemblage fraction. We demonstrate the efficacy of the protocol using a hyperentangled photon pair encoding two copies of a two-qubit state. This represents to our knowledge the first observation of deterministic steering concentration. Our findings are not only fundamentally important but may also be useful for semi device-independent protocols in noisy quantum networks.

中文翻译：

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量子转向蒸馏

我们在理论上和实验上都表明，爱因斯坦-波多尔斯基-罗森转向技术可以被提炼。我们提出了一种蒸馏协议，即使对于任意接近不可操纵的输入，也可以在渐近无穷大限制下输出一个完美相关的系统-单重态组合。作为协议性能的优缺点，我们介绍了组合保真度和单线态组合分数。这些是潜在的有趣数量，它们本身超出了当前范围。值得注意的是，在增加单线态组装分数的意义上，该方案在少数拷贝的非渐近方案中也能很好地工作。我们证明了使用编码两个量子位状态的两个副本的超纠缠光子对协议的功效。据我们所知，这是确定性转向集中度的首次观察。我们的发现不仅在根本上很重要，而且对于嘈杂的量子网络中半独立于设备的协议也可能有用。