Physicists Conduct The Most Massive Test Ever of The Einstein-Podolsky-Rosen Paradox

The largest test of its kind has been conducted by scientists, who discovered that a key quantum mechanical conundrum still remains true even for clouds of hundreds of atoms.

A group of physicists from the University of Basel in Switzerland, co-led by Paolo Colciaghi and Yifan Li, has demonstrated that the Einstein-Podolsky-Rosen (EPR) conundrum scales up using two entangled Bose-Einstein condensates with 700 atoms each.

The study of measuring objects according to quantum theory, or quantum metrology, has profound ramifications, according to the experts.

The researchers state in their report that "our results represent the first observation of the EPR paradox with spatially separated, massive many-particle systems."

They demonstrate that when the system size grows to include more than a thousand heavy particles, the tension between quantum physics and local reality persists.

Even while we're rather adept at mathematically modeling the Universe, our knowledge of how things function is, at best, fragmentary.

Quantum mechanics, a theory that emerged in the early 20th century and was supported by scientist Niels Bohr, is one of the instruments we use to fill one of the gaps. It describes how atomic and subatomic matter behaves. Classical physics fails in this little space; when the previous laws are no longer valid, new laws must be created.

However, quantum physics is not perfect, and in 1935, three eminent scientists discovered a large gap. The famous Einstein-Podolsky-Rosen conundrum was defined by Albert Einstein, Boris Podolsky, and Nathan Rosen.

Nothing can move more quickly than light, am I right? Quantum entanglement, or "spooky action at a distance" as Einstein put it, complicates matters a little. When two (or more) particles are correlated, their attributes are connected; for instance, if one particle spins one way, the other particle spins the opposite way.

It is unknown how or why these particles maintain their connection even when separated by great distances. Scientists are aware that even at such a distance, one particle's characteristics may be inferred from another's by measuring its own.

But according to quantum theory, such characteristics won't be present in the particle until you measure it (a peculiarity examined by the Schrödinger's cat thought experiment).

Furthermore, according to quantum physics, if you are confident of one feature of a particle, like its location, you cannot be certain of another, like its momentum. The Heisenberg uncertainty principle states as such.

According to the local realism principle of classical physics, two objects or sources of energy must interact in order for one to have an effect on the other.

As a result, the EPR paradox is complicated. Even though the measurement is not happening locally, it somehow affects the other particle in an entangled system when you measure one of the particles.

Furthermore, you are aware of the particles to a greater extent than is permitted by the Heisenberg uncertainty principle. And yet, in some unfathomable way, that effect occurs instantly, outpacing the speed of light.

Therefore, the EPR paradox shows that quantum mechanical theory is lacking; it falls short of accurately describing the reality of the universe in which we exist. In what is known as a Bell test (after for its inventor, physicist John Stewart Bell), physicists have mostly tested it on tiny entangled systems, frequently simply a couple of atoms or photons.

Every Bell test that has been performed so far has discovered that the real world acts in a way that is at odds with local realism. But how far does the paradox actually go?

The Bose-Einstein condensates, a state of matter produced by chilling a cloud of bosons to a little amount above absolute zero, come into play at this point. The atoms don't totally cease sinking to their lowest energy state at such low temperatures.

The quantum features of the particles can no longer interfere with one another at these low energies, and they move near enough to kind of overlap, creating a high-density cloud of atoms that acts like a single "super atom" or matter wave.

Colciaghi, Li, and their University of Basel coworkers Philipp Treutlein and Tilman Zibold produced two Bose-Einstein condensates utilizing two clouds that each contained 700 rubidium-87 atoms. They examined the characteristics and spatially separated these condensates by up to 100 micrometers.

They determined the value to measure for each cloud while determining the quantum characteristics of the pseudospin condensates.

They discovered that the characteristics of the two condensates appeared to be associated in a way that could not be explained by chance, proving the EPR paradox's validity on a far wider scale than in earlier Bell tests.

Future quantum research will substantially benefit from the team's conclusions.

"Quantum metrology applications are particularly well suited to our experiment. To decrease the quantum noise of the first system, the researchers suggest using one of the two systems as a reference and the other as a tiny sensor to probe fields and forces with high spatial resolution.

According to the authors, "The demonstration of EPR entanglement in conjunction with the spatial separation and individual addressability of the involved systems is thus not only significant from a fundamental point of view, but also provides the necessary ingredients to exploit EPR entanglement in many-particle systems as a resource."

Have a beautiful cup of tea and a seat down right now. You deserve it.

The research has been published in Physical Review X.