Heidelberg researchers verify non-local correlations in clouds of rubidium atoms
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 for Physics of Heidelberg University recently succeeded in verifying so-called non-local quantum correlations between ultracold clouds of rubidium atoms. Under the direction of Prof. Dr Markus Oberthaler und Prof. Dr Thomas Gasenzer, the researchers were able to gain important new insights into the character of quantum mechanical many-body systems.
Photo: Philipp Kunkel, SynQS
Schematic representation of the experimental implementation: A cigar-shaped cloud of rubidium atoms (blue dots) is cooled to ultra-cold temperatures. Due to collisions between atoms, quantum correlations, also called entanglement, build up (yellow compounds). The atomic cloud is finally imaged onto a camera with the aid of laser light. Due to the high spatial resolution of the camera, correlations between different parts (A and B) of the condensate, and in particular their quantum mechanical character, can be detected.
The correlations that the theory of quantum mechanics predicts are counter-intuitive. These quantum correlations seem to contradict the Heisenberg uncertainty principle, which states that two properties of an object, such as position and speed, can never be precisely determined at the same time.
In quantum mechanical systems, however, two particles can be prepared so as to accurately predict the position of particle two by localising the position of particle one. Similarly, measuring the speed of one particle allows predicting the speed of the other.
"In this case, the position and speed of particle two do need to be precisely determined prior to measurement," explains Prof. Oberthaler. "The measurement result for particle one cannot be immediately present at particle two's position if the two are spatially separate."
The uncertainty principle actually does not support this simultaneous determination of position and speed. But in quantum mechanics, two objects are not considered separate if they are correlated, i.e., entangled, hence resolving the apparent contradiction.
"If we can prove that measurement results of different observables in one system can actually be predicted by measuring a second, remote system, then we can use this evidence to substantiate entanglement as well – and that's exactly what we did in our experiment," states Philipp Kunkel, the study's primary author.
In their experiment, the researchers used a cloud of approximately 11,000 rubidium atoms, which they cooled to extremely low temperatures. Using laser light, they kept the atoms suspended in a vacuum chamber, which allowed them to exclude any disturbing effects, such as collisions with air molecules.
Because quantum effects are detectable only at very low temperatures, working with ultracold atoms is required. Like when measuring position and speed, these extreme conditions allow the internal state of the particles, often called spin, to be measured as well. "By measuring the spin in one half of the cloud, we were able to predict the spin in the other more accurately than the local uncertainty principle would allow," explains Philipp Kunkel.
The characterisation of quantum mechanical many-body systems is important for future applications such as quantum computers and quantum communication, among others. The most recent Heidelberg research results were published in "Science".
P. Kunkel, M. Prüfer, H. Strobel, D. Linnemann, A. Frölian, T. Gasenzer, M. Gärttner, M.K. Oberthaler: Spatially distributed multipartite entanglement enables EPR steering of atomic clouds. Science (published online 27 April 2018), doi: 10.1126/science.aao2254
Prof. Dr. Markus Oberthaler
Kirchhoff Institute for Physics
Phone +49 6221 54-5170
Communications and Marketing
Phone +49 6221 54-2311
Marietta Fuhrmann-Koch | idw - Informationsdienst Wissenschaft
Statistical inference to mimic the operating manner of highly-experienced crystallographer
18.09.2019 | Japan Science and Technology Agency
Scientists create fully electronic 2-dimensional spin transistors
18.09.2019 | University of Groningen
Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Hamburg and the European Molecular Biology Laboratory (EMBL) outstation in the city have developed a new method to watch biomolecules at work. This method dramatically simplifies starting enzymatic reactions by mixing a cocktail of small amounts of liquids with protein crystals. Determination of the protein structures at different times after mixing can be assembled into a time-lapse sequence that shows the molecular foundations of biology.
The functions of biomolecules are determined by their motions and structural changes. Yet it is a formidable challenge to understand these dynamic motions.
At the International Symposium on Automotive Lighting 2019 (ISAL) in Darmstadt from September 23 to 25, 2019, the Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, a provider of research and development services in the field of organic electronics, will present OLED light strips of any length with additional functionalities for the first time at booth no. 37.
Almost everyone is familiar with light strips for interior design. LED strips are available by the metre in DIY stores around the corner and are just as often...
Later during this century, around 2060, a paradigm shift in global energy consumption is expected: we will spend more energy for cooling than for heating....
Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Potsdam (both in Germany) and the University of Toronto (Canada) have pieced together a detailed time-lapse movie revealing all the major steps during the catalytic cycle of an enzyme. Surprisingly, the communication between the protein units is accomplished via a water-network akin to a string telephone. This communication is aligned with a ‘breathing’ motion, that is the expansion and contraction of the protein.
This time-lapse sequence of structures reveals dynamic motions as a fundamental element in the molecular foundations of biology.
Two research teams have succeeded simultaneously in measuring the long-sought Thorium nuclear transition, which enables extremely precise nuclear clocks. TU Wien (Vienna) is part of both teams.
If you want to build the most accurate clock in the world, you need something that "ticks" very fast and extremely precise. In an atomic clock, electrons are...
10.09.2019 | Event News
04.09.2019 | Event News
29.08.2019 | Event News
18.09.2019 | Innovative Products
18.09.2019 | Physics and Astronomy
18.09.2019 | Materials Sciences