Study: Atomic contamination similar to that of gemstones serves as a quantum information carrier

October 1, 2018, Technische Universität Kaiserslautern
The physicists Professor Artur Widera (right) and his doctoral student Felix Schmidt are researching quantum systems. Credit: Koziel/TUK

Impurities in materials are responsible for the colours of gemstones or the performance of modern semiconductors. The same applies to quantum systems, although research has been limited. For the first time, Kaiserslautern researchers were able to implant individual impurities formed by caesium atoms into an ultracold quantum gas of rubidium atoms in a controlled manner. They observed how the impurities exchange quantum mechanical angular momentum (spin) with the gas. They also demonstrated for the first time that caesium atoms can store quantum information. The study was published in the renowned journal Physical Review Letters.

Individual atomic impurities are responsible for various effects in physics and are therefore interesting for experiments. At the TUK, physicists led by Professor Dr. Artur Widera and his doctoral student Felix Schmidt have now observed for the first time how such impurities behave in a Bose-Einstein condensate of . "In physics, this refers to a state of matter that is comparable with liquid and gaseous states. However, such a condensate is a perfect quantum mechanical state that behaves like a wave," says Professor Widera, who heads the Individual Quantum Systems group. For physicists, Bose-Einstein condensates are a popular model for investigating quantum effects.

In their current study, the Kaiserslautern physicists have investigated such a contamination in a quantum gas. They cooled it down to temperatures close to the absolute zero point of -273.15° Celsius. "In this way, we can control a quantum mechanical system," says first author Felix Schmidt. Five to ten caesium were immersed in the Bose-Einstein condensate of around 10,000 rubidium atoms. "The system can be examined under a microscope. The has a size of ten micrometres," continues the doctoral student. The researchers have thus localized individual impurities and observed the change in their electronic structure, the so-called spin, through interaction with the quantum gas. "So far, it has not been possible to observe in such a gas. We are pleased that we succeeded in the experiment," says Schmidt.

The researchers have also investigated whether caesium atoms can be used as information carriers and simultaneously cooled in quantum gas. "For atoms to store information, their electronic state must be preserved," explains Widera. "However, since the condensate interacts with the other atoms, there is a risk that they may lose sensitive information as a result of impact." The researchers have now succeeded for the first time in cooling the in the without losing quantum information.

"The model of individual impurities in an ultracold gas realizes a paradigm of quantum physics," says Professor Widera. "It can serve as a starting point for a variety of other quantum experiments." In particular, the findings of the Kaiserslautern scientists help to better understand what is happening at the quantum level. This could play a role in the future, for example, in understanding superconductors and developing new materials. They could transport electricity over long distances without great energy loss at normal ambient temperatures. So far, this has only been possible at temperatures well below freezing point."

Explore further: Researchers create a quantum entanglement between two physically separated ultra-cold atomic clouds

More information: Felix Schmidt et al. Quantum Spin Dynamics of Individual Neutral Impurities Coupled to a Bose-Einstein Condensate, Physical Review Letters (2018). DOI: 10.1103/PhysRevLett.121.130403

Related Stories

Quantum mechanics: entanglements in ultracold atomic clouds

June 27, 2018

A system's state is characterised as entangled or quantum correlated if two or more particles cannot be described as a combination of separate, independent states but only as a whole. Researchers at the Kirchhoff Institute ...

Quantum particles form droplets

November 28, 2016

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: the atoms form a new type of quantum liquid or quantum droplet state. These so called quantum ...

Bell correlations measured in half a million atoms

April 17, 2017

(Phys.org)—Physicists have demonstrated Bell correlations in the largest physical system to date—an ensemble of half a million atoms at an ultracold temperature of 25 µK. The presence of Bell correlations indicates that ...

Recommended for you

New thermoelectric material delivers record performance

January 17, 2019

Taking advantage of recent advances in using theoretical calculations to predict the properties of new materials, researchers reported Thursday the discovery of a new class of half-Heusler thermoelectric compounds, including ...

Zirconium isotope a master at neutron capture

January 17, 2019

The probability that a nucleus will absorb a neutron is important to many areas of nuclear science, including the production of elements in the cosmos, reactor performance, nuclear medicine and defense applications.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.