They manage to stop time with a 100 nanometer sphere

07/20/2021 at 08:00 CEST

We are getting closer and closer to better observing quantum processes at the scale of macroscopic objects, which are governed by physical laws different from those of elementary particles.

Macroscopic quantum phenomena intrigue physicists since the properties of nature are known at the scale of atoms and subatomic particles. They are among the most relevant phenomena in physics.

Quantum effects prevail at the atomic scale and of subatomic particles: they show that, at these levels of reality, matter and energy are confused due to the wave-particle duality. They adopt strange behaviors that escape classical physics.

Those quantum effects are only seen in electrons and other smaller physical components. However, in a laboratory conditions can be created to obtain quantum effects in macroscopic objects: most of the time, it has been achieved with clouds of millions of atoms.

Until now, it has been possible to appreciate macroscopic quantum phenomena in superfluidity (discovered in 1937) or in superconductivity (discovered in 1911), and also in the topological states of matter.

New milestones

New milestonesThis year quantum entanglement has also been achieved, which allows two distant elementary particles to share a common quantum state, in vibrating drums made of two aluminum membranes about 10 micrometers long (a micrometer is equal to one thousandth of a millimeter).

Now, researchers from the Federal Polytechnic School of Zurich (ETH Zurich) have achieved another milestone in the race to understand how quantum processes work on a macroscopic scale: they took a glass sphere to the quantum limit and observed the quantum phenomena that occurred inside.

The sphere measured one hundred nanometers, which means that it is a thousand times smaller than the thickness of a human hair. It is small for our perception, but huge for the elementary physical levels because it consists of 10 million atoms.

Related Topic: Quantum Effects Scale to Unprecedented Macroscopic Levels

Optical trap

Optical trapThe sphere was levitated in an optical trap and suspended in the air by a laser. The optical trap was in a vacuum vessel and cooled to minus 269 ° C.

In order for it to reach the quantum state, its energy level had to be further reduced, which the researchers achieved with a second laser that allowed them to slow its oscillation speed to its ground state.

The result can be compared to the swaying of a swing that we manage to reduce to a state of apparent stillness, as if we stopped time for an instant, enough to observe the quantum phenomena associated with the swaying of a macroscopic object.

The oscillations of the sphere, and therefore its energy of motion, were reduced to the quantum limit: the point at which the uncertainty ratio of quantum mechanics prevents further reduction, the authors of this research point out.

“This is the first time that such a method has been used to monitor the quantum state of a macroscopic object in free space,” explains lead author and professor of photonics, Lukas Novotny, in a statement.

Important advantages

Important advantagesAlthough similar results have been obtained with spheres in optical resonators, this approach has important advantages: it is less susceptible to disturbances and, by turning off the laser light, the sphere can, if necessary, be examined in complete isolation, the researchers note.

The result obtained will help to better understand quantum mechanics, bringing it even closer to macroscopic size and thus enabling the development of new technologies.

The researchers hope their work could be useful in better studying how quantum mechanics makes elementary particles behave like waves.

Also that enables the development of new generation sensors more sophisticated than the current ones.


ReferenceQuantum control of a nanoparticle optically levitated in cryogenic free space. Felix Tebbenjohanns et al. Nature volume 595, pages378–382 (2021). DOI: https: //

Top image: Gerd Altmann on Pixabay.

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