Proof of absence of spooky action at a distance in quantum correlations

Mani Lal Bhaumik

The enigmatic nonlocal quantum correlation that was famously derided by Einstein as "spooky action at a distance" has now been experimentally demonstrated to be authentic. The quantum entanglement and nonlocal correlations emerged as inevitable consequences of John Bell's epochal paper on Bell's inequality. However, in spite of some extraordinary applications as well as attempts to explain the reason for quantum nonlocality, a satisfactory account of how Nature accomplishes this astounding phenomenon is yet to emerge. A cogent mechanism for the occurrence of this incredible event is presented in terms of a plausible quantum mechanical Einstein–Rosen bridge. Quanta 2018; 7: 111–117.

Aleksandr V. Belinsky, Michael H. Shulman

David Park

Maria Fuwa, Shuntaro Takeda, Marcin Zwierz +2 more

A single quantum particle can be described by a wavefunction that spreads over arbitrarily large distances; however, it is never detected in two (or more) places. This strange phenomenon is explained in the quantum theory by what Einstein repudiated as ‘spooky action at a distance’: the instantaneous nonlocal collapse of the wavefunction to wherever the particle is detected. Here we demonstrate this single-particle spooky action, with no efficiency loophole, by splitting a single photon between two laboratories and experimentally testing whether the choice of measurement in one laboratory really causes a change in the local quantum state in the other laboratory. To this end, we use homodyne measurements with six different measurement settings and quantitatively verify Einstein’s spooky action by violating an Einstein–Podolsky–Rosen-steering inequality by 0.042±0.006. Our experiment also verifies the entanglement of the split single photon even when one side is untrusted. Quantum mechanics exhibit many unusual features, including Einstein’s so-called ‘spooky action at a distance’, wherein a wavefunction collapses at all points except where it is detected. Using homodyne measurements, Fuwa et al. verify this effect for a single photon split between two labs.

Feng Liu, Fei Li, Yunxia Wei

Nakka Gurappa

The delayed-choice entanglement swapping experiments, both in space and time, are casually explained at a single quantum level by using the `wave-particle non-dualistic interpretation of quantum mechanics'. In order to achieve this, the actual mechanisms involved in the Wheeler's delayed-choice experiment and Einstein's spooky-action-at-a-distance are uncovered from the quantum formalism. The continuity in the motion of any individual quantum particle, due to the constants of motion, is responsible for the outcomes of Wheeler's delayed-choice experiment. The purpose for the existence of spooky action in Nature is to strictly maintain the conservation laws in absence of exchange-interactions. The presence of a casual structure in the entanglement swapping is shown by detailed analysis of the experimental results presented in the papers, ``X-S. Ma et al., Nature. Phys. 8, 480, (2012)'' and ``E. Megidish et al., Phys. Rev. Lett. 110, 210403 (2013)'', at the level of individual quantum events. These experiments are directly confirming the wave-particle non-duality.