Atoms Can be in Two Places at the Same Time: Physicists Investigate Quantum Mechanics

Can atoms be in two places at once? That may be the case. According to the predictions of quantum mechanics, microscopic objects can take different paths at the same time. In fact, researchers have found that Caesium atoms can take two paths at the same time.

About 100 years ago, physicists created a new field of physics, called quantum mechanics. According to quantum theory, objects of the quantum world no longer move along a single well-defined path. Instead, they can simultaneously take different paths and end up at different places at once.

At the level of atoms, it looks as if objects may indeed obey quantum mechanical laws. In fact, many experiments over the years have confirmed quantum mechanical predictions. But in our macroscopic daily experience, we witness a football flying exactly one path-why? Good question.

"There are two different interpretations," said Andrea Alberti, one of the researchers, in a news release. "Quantum mechanics allows superposition states of large, macroscopic objects. But these states are very fragile, even following the football with our eyes is enough to destroy the superposition and make it follow a definite trajectory."

Scientists believe that footballs and other large objects obey different rules than those that apply to single atoms. In order to investigate this a bit further, the researchers came up with an experimental scheme.

With two optical tweezers, the scientists grabbed a single Caesium atom and pulled it in two opposing directions. In the macro-realist's world the atom would then be at only one of the two final locations. Quantum-mechanically, though, the atom would instead occupy a superposition of the two positions.

"We have now used indirect measurements to determine the final position of the atom in the most gentle way possible," said Carsten Robens, one of the researchers, in a news release. In the end, they found that the atom did indeed take different paths at the same time.

That said, this isn't proof that quantum mechanics hold for large objects. The researchers hope to separate the Caesium atom's two positions by several millimeters.

The findings are published in the journal Physical Review X.

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