Sequential propagation of a single photon through five measurement contexts in a three-path interferometer

TL;DR

This paper demonstrates quantum contextuality using a three-path interferometer where five measurement contexts are sequentially realized, revealing paradoxical interference effects explained by weak measurements.

Contribution

Introduces a novel three-path interferometer setup that sequentially implements all contexts needed for quantum contextuality demonstration, providing new insights into wave-particle duality.

Findings

Observation of paths appearing blocked by destructive interference

Conditional currents explained by weak measurements

Weak values bridge wave effects and particle detection

Abstract

Quantum contextuality describes scenarios in which it is impossible to explain the experimental evidence in terms of a measurement independent reality. Here, I introduce a three-path interferometer in which all five contexts needed for a demonstration of contextuality are realized in sequence. It is then possible to observe a paradoxical situation where the paths connecting input ports to their corresponding output ports appear to be blocked by destructive interference. It is shown that the conditional currents observed in weak measurements provide a consistent explanation of the paradox, indicating that weak values might help to bridge the gap between wavelike propagation effects and local particle detection.