Quantum weirdness: backflow (Introduction)

by David Turell , Monday, July 24, 2017, 15:54 (2680 days ago) @ dhw

Push a quantum particle forward and it may go in the opposite direction:

http://bigthink.com/paul-ratner/weird-quantum-mechanics-discovery-says-pushing-particle...

"Quantum mechanics continues to provide brain-busting discoveries as mathematicians find that quantum mechanical particles can move in the opposite direction of where they are being pushed. That’s like pushing a ball forward and having it roll back towards you instead.

"Scientists at Universities of York, Munich and Cardiff showed that on microscopic levels, quantum particles can travel in reverse of their momentum, exhibiting a special property called “backflow”.

"Researchers were aware of such movement previously but in free” quantum particles that don’t have any force acting on them. By using analysis and numerical methods, they found that backflow is always there, but as a small hard-to-measure effect. 

"What’s responsible for this surprising property? Wave-particle duality, which holds that every particle may behave as a particle or a wave, and the “probabilistic nature” of quantum mechanics where particle properties are not fixated until observed.

***

“'This new theoretical analysis into quantum mechanical particles shows that this ‘backflow’ effect is ubiquitous in quantum physics,” said Bostelmann in a press release. “We have shown that backflow can always occur, even if a force is acting on the quantum particle while it travels. The backflow effect is the result of wave-particle duality and the probabilistic nature of quantum mechanics, and it is already well understood in an idealised case of force-free motion.”

"Dr. Daniela Cadamuro from the Technical University of Munich explained that while the scientists were aware of the backflow effect, it was always observed when no outside forces were acting on a particle, and the researchers showed that backflow continues to occur even with external forces present, meaning that such forces “don't destroy the backflow effect, which is an exciting new discovery.'”

Comment: Just when you think it can't get weirder it does.