Cardiff Mathematics Lecturer part of pioneering quantum breakthrough

20 July 2017

Green spiral

Dr Gandalf Lechner, Lecturer at the School of Mathematics was part of a team of researchers who have discovered that quantum mechanical particles have the unique ability to move in the opposite direction to the way in which they are being pushed.

This is a ground-breaking discovery for the researchers from Cardiff University, the University of York, and the Technical University of Munich (TUM) because it is the first time that such movement has been observed in a particle where external forces are acting on it. Previously, this behaviour had only been seen in "free" quantum particles, where no force was acting on them.

According to Newton's Laws of Motion, acceleration is produced when a force acts on a mass. Once the force acts on an object, it will travel in the same direction as its momentum, so for example, a car going forwards will travel forwards, but not backwards.

Dr Lechner explained how "Forces can, of course, make a particle go backwards – that is, they can reflect it – and this naturally leads to increased backflow. However, we could show that even in a completely reflection-free medium, backflow occurs. In the presence of reflection, on the other hand, we found that backflow remains a small effect, and estimated its magnitude."

The International Business Times added that "this discovery is a big step forward in the field of quantum mechanics research, which is working towards one day making it possible to build ultra-fast quantum computers and super-high resolution-imaging solutions”.

The study, entitled "Quantum backflow and scattering" is published by the American Physical Society in the journal Physical Review A.

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