Technology

How teleporting light and levitating diamonds offer proof of quantum theory

Physicists and researchers working in several labs are about to prove a theory that will lay the foundation for an advanced understanding of … well, everything.

The theory in question is quantum mechanics, a form of physics that relies on subatomic particle motions to explain the natural universe. Prove that it is one of the most difficult problems for scientists to solve.

To move from the theoretical column to the canon of scientific fact, physicists must observe certain phenomena whose existence has so far been demonstrated only on paper. This would be quite complicated because, as shown the observer effect the mere fact of looking at a quantum particle alters its work.

To get around this problem, physicists project to capture a particle of light and levitate it between lasers using a device invented in the 1970s called a forceps optical.

The optical gripper, or single beam force gradient trap, exploits the fact that light exerts a pressure, in the form of radiation, on the mass.

One of the ways to think about it is to imagine a single particle of light, that is a basketball. Normally, this particle moves so fast that, like a basketball dribbling at an extreme speed, there is no way to know at any time if it goes up or down. To determine its position, you must take a snapshot or a measurement.

Now imagine that it's possible to get on and off at the same time. And that, by measuring it, you made it go up and down up and down. This makes it almost impossible to observe the transition from the two states to one state.

In the theory of quantum mechanics, it is postulated that particles can exist in two different states at the same time. But only for incredibly short moments. Imagine that basketball is going up and down for a nanosecond, then up or down. The moment this transition takes place is called quantum collapse.

Physicists hope to use optical tweezers to slow down particles by levitating them. This state is called a ground state and it is necessary to observe the quantum collapse according to a strategy put forward in 2013 by research teams led by Tongcang Li and Lu Ming Duan.

Once slowed down, the particle will then become entangled in a defective atomic nanodiamond that is also levitated. Then, through a teleportation process called "superposition", physicists can simultaneously observe the particle in two different physical positions (ie, its north pole facing up and down), thanks to its entanglement.

Once the researchers have realized the superposition, in these incredible conditions, they will be able to observe a quantum collapse while the universe will decide the direction to which the pole of the particle is facing.

It sounds a bit far-fetched, but widespread belief among physicists supports quantum mechanics. And observing a quantum collapse would go a long way toward illuminating the next steps beyond the initial theories.

For a more in-depth dive into Li-Duan's experiences, check out this article on The Conversation by Mishkat Bhattacharya and Nick Vamivakas.

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