Cheshire cat quantum effect may not be real, scientists explain

In 2013, a team of scientists named a quantum Cheshire cat effect quantum phenomenoninspired by the homonymous cat present in the work Alice in Wonderland by the English author, Lewis Carroll.

Just as the cat disappeared leaving only traces of its smile, researchers suggested that quantum particles can separate themselves from their properties — in other words, the properties could travel in paths that the particle could not. But it seems that things are not quite like that.

In addition to separating properties, the quantum Cheshire cat effect could also disembody multiple properties simultaneously and even separate a particle's wave-particle duality. However, a recent study published in the scientific journal New Journal of Physics suggests that the experiments that named the effect in 2013 did not present assertive results.

By analyzing the Cheshire cat's quantum effect, researchers discovered that it may not exist.Source: Shutterstock

The researchers explain that the particles were not separating themselves from their properties, in reality, they were presenting a characteristic of quantum mechanics: contextuality. They explain that there is no quantum Cheshire cat effect and that experiments produce a divergent result when different measurements are taken.

“Most people know that quantum mechanics is weird, but identifying what causes this weirdness is still an active area of ​​research. This was slowly formalized into a notion called contextuality — that quantum systems change depending on the measurements you make on them”, said researcher and one of the study’s authors, Jonte Hance, from Hiroshima University (Japan) and the University of Bristol (England).

Cheshire cat quantum effect? No.

In an official statement, scientists explain that the sequence of measurements in a quantum system can produce different results depending on the order in which the measurement is carried out.

This effect is exactly what they call contextuality, as the way the experiment is observed will affect the outcome of the data. They explain that Measurements carried out in 2013 were essential to produce the quantum Cheshire cat effect, but they were not correct.

As the quantum Cheshire cat effect is paradoxical and has been 'debunked', the team plans to investigate other effects considered paradoxical to understand whether they are part of the contextuality of quantum physics. Based on the data and future researchscientists seek to explain why measurements change in different quantum systems.

“We want to fix this by showing that different results are obtained if a quantum system is measured in different ways, and that the original quantum Cheshire cat interpretation only happens if you combine the results of these different measurements in a very specific way, and ignore this related change measurement,” said another professor at Hiroshima University, Holger Hofmann.

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