quantum physics
December 19, 2014

Quantum physics is less complicated than we thought

Brett Smith for redOrbit.com - Your Universe Online

Two phenomena, ‘wave-particle duality’ and the ‘uncertainty principle’, have confounded particle physicists for years, but now a new research paper published in the journal Nature Communications has found that these two phenomena are actually the same thing.

"The connection between uncertainty and wave-particle duality comes out very naturally when you consider them as questions about what information you can gain about a system. Our result highlights the power of thinking about physics from the perspective of information," said study author Stephanie Wehner, an associate professor of quantum physics the Delft University of Technology in the Netherlands.

Wave-particle duality is the idea that a quantum particle can act like a wave, but the wave-like action vanishes if researchers attempt to view the object. For example, in a double-slit experiment, single particles are shot one at a time at a screen with two thin slits. The particles ultimately stack up in a striped pattern – which is not how particles should act, but more like how waves would act. In a bizarre twist, this wave pattern vanishes if observers check to see if it is happening.

wave-particle duality

Quantum physics says that particles can behave like waves, and vice versa. Researchers have now shown that this 'wave-particle duality' is simply the quantum uncertainty principle in disguise. (Credit: Timothy Yeo/CQT, National University of Singapore)

The quantum uncertainty principle is the concept that there is no way to find out pairs of characteristics of a quantum particle at once. For instance, the more specifically the location of an atom is known, the less accurately researchers can find out how quickly it's moving. This limitation is determined to be a limit of nature, not a statement on quantum science's current capacity to measure. The new study indicates that what you can learn of the wave, as opposed to the particle behavior of a system, is restricted in precisely the same way.

These concepts have been a part of particle physics since the early 20th century, and in the new study, researchers showed that wave–particle duality relations (WPDRs) correspond precisely to modern ideas about the uncertainty principle in terms of energy, roughly speaking. The team essentially found common connections between equations for the two phenomena.

"We were guided by a gut feeling, and only a gut feeling, that there should be a connection," said study author Patrick Coles, currently a postdoctoral fellow at the University of Waterloo.

"It was like we had discovered the 'Rosetta Stone' that connected two different languages," he added. "The literature on wave-particle duality was like hieroglyphics that we could now translate into our native tongue. We had several eureka moments when we finally understood what people had done.”

In addition to potentially simplifying concepts in particle physics, the new study could also lead to improvements in quantum cryptography, the researchers said.

Earlier this month, physicists at the University of Warsaw took another step forward in the pursuit of quantum computing and cryptography by developing an ‘atomic memory.’

“Until now, quantum memory required highly sophisticated laboratory equipment and complex techniques chilling the systems to extremely low temperatures approaching absolute zero. The atomic memory device we have been able to create operates at far higher temperatures, in the region of tens of degrees Celsius, which are significantly easier to maintain,” said Radek Chrapkiewicz, a member of the Warsaw team.

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