May 20, 2013
Observing Competition In The Quantum World
University of Innsbruck
"When water boils, its molecules are released as vapor. We call this change of the physical state of matter a phase transition," explains Sebastian Diehl from the Institute of Theoretical Physics at the University of Innsbruck. Together with his colleagues from the Institute for Experimental Physics and the theorist Markus Mueller from the Complutense University of Madrid, he studied the transition between two quantum mechanical orders in a way never before observed. The quantum physicists in Innsbruck use a new device for the experiment, which is currently considered to be one of the most promising developments in quantum physics: a quantum simulator. It is based on a small-scale quantum computer and can simulate physical phenomena a classical computer cannot investigate efficiently. "Such a quantum simulator allows us to experimentally study quantum phenomena in many-body systems that are coupled to their environment," explain experimental physicists Philipp Schindler and Thomas Monz.
Observing the competition
The experiment demands an enormous degree of precision, which requires immediate error corrections to be able to simulate the physical processes correctly. Since a comprehensive error correction, as developed for quantum computers, involves considerable resource overheads, the physicists in Innsbruck chose another promising alternative path. They identified the most important sources of error occurring during the simulation and specifically targeted them. Schindler is convinced: "This way of error reduction will surely set an example for other experiments. While general quantum error correction remains a long-term goal, we may be able to successfully use this type of error correction a lot sooner for reliable quantum simulation of larger systems," adds Markus Mueller.
Interweaving theory with experiment
Such an experimental study of the nature of quantum mechanical phase transitions is internationally unique. It was only possible because advanced experimental know-how was successfully combined with theoretical research, which was carried out in close collaboration between physicists from Innsbruck and Madrid. "This link between theoretical and experimental physicists who work closely together, and in Innsbruck under one roof, is possible in very few places. It is also one of the great strengths of quantum physics research carried out in Innsbruck. And this research, once again, led us into an area of physics that hadn't been explored before," says Rainer Blatt. "In this experiment the physics of many-body systems is successfully simulated with a few trapped ions. This clearly shows the potential and the possibilities of quantum simulation," adds Peter Zoller.
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