Computer-assisted methods aid Heidelberg physicists in reproducing experiment with ultracold atoms
Two researchers at Heidelberg University have developed a model system that enables a better understanding of the processes in a quantum-physical experiment with ultracold atoms.
Using computer-assisted methods, Prof. Dr Sandro Wimberger and David Fischer from the Institute for Theoretical Physics discovered physical laws that point to the universal properties of this system. Their results were published in the journal “Annalen der Physik”.
Under certain conditions, small particles follow completely different physical laws than those we are accustomed to. “Observing such quantum-physical phenomena, however, is sometimes difficult and requires working with small and isolated systems and to investigate those.
But perfect isolation from the environment is never possible, so external influences can easily destroy the fragile state of the quantum system,” explains primary author David Fischer, a student of physics at Heidelberg University. For experiments in this field, keeping such disruptions under control is of great interest.
“This control enables us not only to ensure the coherence of the system, but it can also be used selectively to effect special conditions,” emphasises Prof. Wimberger.
Ultracold atoms filled into so-called potential wells have proven to be suitable test objects in many experiments. A special laser configuration is used to generate a barrier that locks the atoms in a small area. If multiple wells are then brought close enough together, the atoms have the ability to “tunnel” from one well into an adjacent one.
They are still trapped in the wells, but can move from one well to another, according to the Heidelberg physicists. The temperature of the atoms, which is only just above absolute zero at -273.15 degrees Celsius, favours this quantum-mechanical behaviour.
In developing their model system, David Fischer and Sandro Wimberger reproduced an experiment carried out at the Technical University of Kaiserslautern. There, the behaviour of cold atoms in a chain of potential wells was investigated. The researchers filled the chain with atoms, emptied the middle well, and watched it refill with atoms from the other wells.
“The results of this study suggest that decoherence, i.e. external interference, plays a critical role in this process. What is unclear is which microscopic processes the quantum system uses to interact with the environment,” says David Fischer.
In their computer-assisted simulation of the refilling process, the two Heidelberg researchers tested various hypotheses and explored which processes actually influenced the behaviour of the model system. Among other things, they noticed that the time required for the refilling process varied based on the system parameters. This duration follows a power law, depending on the decoherence rate specified by the researchers.
“In physics, this is often a sign of a universal behaviour of the system that is valid for all scales, hence simplifying the overall problem,” states Prof. Wimberger.
D. Fischer and S. Wimberger: Models for a multimode bosonic tunneling junction, Ann. Phys. (2017) (published online 13 February 2017), doi: 10.1002/andp.201600327
Prof. Dr Sandro Wimberger
Institute for Theoretical Physics
Phone +49 6221 54-9449
Communications and Marketing
Phone +49 6221 54-2311
Marietta Fuhrmann-Koch | idw - Informationsdienst Wissenschaft
A chip for environmental and health monitoring
15.12.2017 | Friedrich-Alexander-Universität Erlangen-Nürnberg
New type of smart windows use liquid to switch from clear to reflective
14.12.2017 | The Optical Society
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong
Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
14.12.2017 | Health and Medicine
14.12.2017 | Physics and Astronomy
14.12.2017 | Life Sciences