A tiny nanoparticle has been chilled tothe max.

Physicists cooled a nanoparticle to thelowest temperature allowed by quantum mechanics. The particles motion reachedwhats known as the ground state, or lowest possible energy level.

In a typical material, the amount thatits atoms jostle around indicates its temperature. But in the case of thenanoparticle, scientists can define an effective temperature based on themotion of the entire nanoparticle, which is made up of about 100 million atoms.That temperature reached twelve-millionths of a kelvin, scientists reportJanuary 30 in Science.

Levitating it with a laser inside of aspecially designed cavity, Markus Aspelmeyer of the University of Vienna andcolleagues reduced the nanoparticles motion to the ground state, a minimum level set by theHeisenberg uncertainty principle, which states that theres a limit to how wellyou can simultaneously know the position and momentum of an object.

While quantum mechanics is unmistakablein tiny atoms and electrons, its effects are harder to observe on larger scales.To better understand the theory, physicists have previously isolated its effects in other solid objects, such as vibrating membranes or beams (SN: 4/25/18). But nanoparticles have theadvantage that they can be levitated and precisely controlled with lasers.

Eventually, Aspelmeyer and colleaguesaim to use cooled nanoparticles to study how gravity behaves for quantumobjects, a poorly understood realm of physics. This is the really long-termdream, he says.

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Scientists cooled a nanoparticle to the quantum limit - Science News