It has been conjectured that counterfactual communication is impossible, even for post-selected quantum particles. We strongly challenge this by proposing precisely such a counterfactual scheme where—unambiguously—none of Alice’s photons that correctly contribute to her information about Bob’s message have been to Bob. We demonstrate counterfactuality experimentally by means of weak measurements, and conceptually using consistent histories—thus simultaneously satisfying both criteria without loopholes. Importantly, the fidelity of Alice learning Bob’s bit can be made arbitrarily close to unity.

中文翻译：

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物理定律并不禁止反事实交流

据推测，即使对于后选择的量子粒子，反事实通信也是不可能的。我们通过精确地提出这样一个反事实方案来强烈挑战这一点，其中——毫不含糊地——爱丽丝的光子中没有一个正确地为她关于鲍勃的消息的信息做出贡献的光子已经到达鲍勃。我们通过弱测量在实验上证明反事实，并在概念上使用一致的历史——因此同时满足两个标准而没有漏洞。重要的是，爱丽丝学习鲍勃比特的保真度可以任意接近统一。