Einstein-Podolsky-Rosen Paradox Observed in Many-Particle System for the First Time

Sunday, April 29, 2018

Einstein-Podolsky-Rosen Paradox Observed in Many-Particle System for the First Time

⯀ Physicists have observed the quantum mechanical Einstein-Podolsky-Rosen paradox in a system of several hundred interacting atoms for the first time. The phenomenon dates back to a famous thought experiment from 1935. It allows measurement results to be predicted precisely and could be used in new types of sensors and imaging methods for electromagnetic fields.

Physicists from the University of Basel have observed the quantum mechanical Einstein-Podolsky-Rosen paradox in a system of several hundred interacting atoms for the first time. The phenomenon dates back to a famous thought experiment from 1935. It allows measurement results to be predicted precisely and could be used in new types of sensors and imaging methods for electromagnetic fields.

The findings were recently published in the journal Science.

Einstein-Podolsky-Rosen Paradox Observed in Many-Particle System for the First TimeThe Heisenberg uncertainty relation, which states that it is impossible to simultaneously predict, the measurements of a particle’s position and momentum, or of two components of a spin, with arbitrary precision is a base principle of quantum mechanics.

This factor fundamentally limits how precisely can we predict the results of measurements on a physical system.

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In 1935, Albert Einstein, Boris Podolsky, and Nathan Rosen published a famous paper in which they showed that precise predictions are theoretically possible under certain circumstances. To do so, they considered two systems, A and B, in what is known as an “entangled” state, in which their properties are strongly correlated. "While we have thus shown that the wave function does not provide a complete description of the physical reality, we left open the question of whether or not such a description exists. We believe, however, that such a theory is possible.," they concluded.

In the past, experiments have used light or individual atoms to study the EPR paradox, which takes its initials from the scientists who discovered it. Now, a team of physicists led by Professor Philipp Treutlein of the Department of Physics at the University of Basel and the Swiss Nanoscience Institute (SNI) has successfully observed the EPR paradox using a many-particle system of several hundred interacting atoms for the first time.


"It’s fascinating to observe such a fundamental phenomenon of quantum physics in ever larger systems. At the same time, our experiments establish a link between two of Einstein’s most important works."
The experiment used lasers to cool atoms to just a few billionths of a degree above absolute zero. At these temperatures, the atoms behave entirely according to the laws of quantum mechanics and form what is known as a Bose-Einstein condensate – a state of matter that Einstein predicted in another pioneering paper in 1925. In this ultracold cloud, the atoms constantly collide with one another, causing their spins to become entangled.

The researchers then took measurements of the spin in spatially separated regions of the condensate. Thanks to high-resolution imaging, they were able to measure the spin correlations between the separate regions directly and, at the same time, to localize the atoms in precisely defined positions. With their experiment, the researchers succeeded in using measurements in a given region to predict the results for another region.

“The results of the measurements in the two regions were so strongly correlated that they allowed us to demonstrate the EPR paradox,” says PhD student Matteo Fadel, lead author of the study. “It’s fascinating to observe such a fundamental phenomenon of quantum physics in ever larger systems. At the same time, our experiments establish a link between two of Einstein’s most important works.”

In addition to their basic research, the scientists are already speculating about possible applications for their discovery. For example, the correlations that are at the heart of the EPR paradox could be used to improve atomic sensors and imaging methods for electromagnetic fields.



SOURCE  University of Basel

By  33rd Square