Photons reveal a weird effect called the quantum pigeonhole paradox

Xi-Jun Ren, Pei Wang

John Beaver

John Beaver

Ming-Cheng Chen, Chang Liu, Yi-Han Luo +7 more

We experimentally demonstrate that when three single photons transmit through two polarization channels, in a well-defined pre- and postselected ensemble, there are no two photons in the same polarization channel by weak-strength measurement, a counterintuitive quantum counting effect called the quantum pigeonhole paradox. We further show that this effect breaks down in second-order measurement. These results indicate the existence of the quantum pigeonhole paradox and its operating regime.

Weidong Tang

Hardy-like proofs for some quantum mechanical properties, such as Hardy-like nonlocality and Hardy-like contextuality, provide us two probabilistic no-go theorems by logical contradictions. Inspired by this, one may conjure that there are some other nonclassical properties which can also be revealed by Hardy-like arguments. In this work, we present an unconventional kind of quantum pigeonhole effects using Hardy-like arguments and show how to systematically construct them. Besides, we introduce a kind of ``projected-stabilizer state, say projected-coloring graph states, associated with a special type of coloring graphs called projected-coloring graph states. We build a one-to-one connection between a given projected-coloring graph (state) and a Hardy-like quantum pigeonhole In this sense a Hardy-like quantum pigeonhole paradox may also be referred to as a ``quantum coloring paradox.

A Correspondent