论文标题
前后选择的量子步行的非古典振荡
Nonclassical oscillations in pre- and post-selected quantum walks
论文作者
论文摘要
量子步行是经典随机步行的对应物。它们可以更快地传播，可以在信息处理任务中利用，并构成了许多量子系统的多功能模拟平台。但是，他们的某些特性可以用经典的光模拟。这引起了一个问题：该模型的哪个方面确实是非古典的？我们通过基于选择前后悖论进行光子实验来解决它。悖论意味着，如果某人可以选择询问，即使粒子在偶数步骤处的位置x = 0，还是在奇数时间步长的位置x = d（d> 1）位置，无论问题如何，答案都是正面的。因此，尽管该模型一次允许一次跳跃一个位置，但粒子似乎会发生长距离振荡。我们将这种悖论转化为类似钟形的不平等现象，并在实验上确认其违反了八个标准偏差。
Quantum walks are counterparts of classical random walks. They spread faster, which can be exploited in information processing tasks, and constitute a versatile simulation platform for many quantum systems. Yet, some of their properties can be emulated with classical light. This rises a question: which aspects of the model are truly nonclassical? We address it by carrying out a photonic experiment based on a pre- and post-selection paradox. The paradox implies that if somebody could choose to ask, either if the particle is at position x = 0 at even time steps, or at position x = d (d > 1) at odd time steps, the answer would be positive, no matter the question asked. Therefore, the particle seems to undergo long distance oscillations despite the fact that the model allows to jump one position at a time. We translate this paradox into a Bell-like inequality and experimentally confirm its violation up to eight standard deviations.
