Nonclassical oscillations in pre- and post-selected quantum walks

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 their properties emulated with light. This rises question: aspects the model truly nonclassical? We address it by carrying out photonic experiment based on pre- post-selection paradox. The paradox implies that if somebody could choose to ask, either particle is at position x = 0 even time steps, or d (d > 1) odd answer would positive, no matter question asked. Therefore, seems undergo long distance oscillations despite fact allows jump one time. translate this into Bell-like inequality experimentally confirm its violation up eight standard deviations.