Quantum Mechanics at Macroscopic Scales

nanosphere at the quan 1
nanosphere at the quan 1

Quantum mechanics deals with the behavior of the Universe at the super-small scale. These are atoms and subatomic particles that work in ways that classical physics cannot explain. To explore these differences between quantum and classical, scientists are trying to make larger objects behave in a quantum-like way. The study of Quantum Mechanics at Macroscopic Scales has been done on an extraordinarily small scale.

When it comes to this particular work, we can think of a tiny glass nanosphere, 100 nanometers in diameter, about a thousand times smaller than the thickness of a human hair. To our minds, this is very, very small, but in terms of quantum physics it's actually pretty big, made up of 10 million atoms.
We can say that introducing such a nanosphere into the field of quantum mechanics is actually a great achievement. Using carefully calibrated laser lights, the scientists worked by suspending the nanosphere in its lowest quantum mechanical state, one of the extremely limited motions where quantum behavior can begin to occur.
"This is the first time that such a method has been used to check the quantum state of a macroscopic object in empty space," says Lukas Novotny, professor of photonics at ETH Zurich in Switzerland.
To obtain quantum states, the motion and energy values ​​must change exactly downwards. Novotny and colleagues used a vacuum vessel cooled to -269 degrees Celsius (-452 degrees Fahrenheit) before using a feedback system to further adjust.
Using the interference patterns created by the two laser beams, the researchers calculated the exact position of the nanosphere inside its chamber, and from there, using the electric field created by the two electrodes, they calculated the precise settings needed to bring the object's motion close to zero.
A playground is not much different from slowing it down by pushing and pulling until it reaches a starting point of the created swing. Once this lowest quantum mechanical state is reached, further experiments can be started.

“To see quantum effects clearly, the nanosphere needs to be slowed down to its entire motional ground state,” says electrical engineer Felix Tebbenjohanns of ETH Zurich.

"This means that we freeze the motion energy of the sphere to a minimum close to the quantum mechanical zero point motion."
Optical resonator was used to stabilize objects using light, although similar results have been obtained before.

The approach used here better protects the nanosphere from degradation and means that the object can be seen in isolation after the laser is turned off – but this will require more research to achieve.

One of the ways researchers hope their findings can be useful is to study what quantum mechanics uses to make fundamental particles behave like waves. It's thought that super-sensitive setups like this nanosphere could also help develop next-generation sensors beyond anything we have today.

Being able to levitate such a large sphere in a cryogenic environment represents a significant leap towards the macroscopic scale, where the line between classical and quantum can be studied.

“With the fact that the potential for optical trapping is highly controllable, our experimental platform offers a way to probe quantum mechanics at macroscopic scales,” the researchers write in their published paper.

Source: Science Alert

16.07.2021

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