This collective condition is called - named for its intellectual fathers - Bose-Einstein condensate. Physicists at the Physikalisch-Technische Bundesanstalt (PTB) have now succeeded for the first time worldwide in producing a Bose-Einstein condensate from the alkaline earth element calcium.
Like a giant wave in the midst of a sea of gaseous calcium atoms, the Bose-Einstein condensate soars. It is composed of approx. 20 000 atoms which are normally not visible to the human eye. However the waves which describe the atoms quantum mechanically, all oscillate synchronously in the condensate and accumulate to form a dense giant wave. In this way, the microscopic pile-up of atoms suddenly becomes macroscopic and therefore visible. Credit: PTB
The use of alkaline earth atoms creates new potential for precision measurements, for example for the determination of gravitational fields. Because as opposed to previous Bose-Einstein condensates from alkali atoms, alkaline earth metals react one million times more responsively to the wavelength at optical excitations – a fact which can be used for super exact measurements. Theresults have now been published in Physical Review Letters.
The quantum mechanical background
Atoms in gases at room temperature behave like a wild bunch: They fly pell-mell at different speeds, collide with one another, and are then hurled again in another direction. However at extremely low temperatures close to the absolute zero point at zero Kelvin (–273.15 degrees Celsius) they nearly come to a standstill. At this point, the laws of quantum mechanics come into effect; these cannot be observed in everyday life and have an unsettling effect on many a non-physicist. The idea of atoms as small spheres does not work any longer. In fact, atoms can now only be described quantum mechanically by waves. Like water waves they can overlap each other. In the case of a Bose-Einstein condensate, the wave functions of up to one million atoms are so synchronised that they pile up to form a giant wave. These formations can grow to one millimeter in size and they can then be photographed. The microcosm presents itself macroscopically – it becomes visible for the observer. In the past few years, such Bose-Einstein condensates have been used for diverse investigations on the fundamentals of quantum mechanics, as a model system for solids or in quantum information.
The wave patterns of excited Bose-Einstein condensates are very responsive to their environment. Thus, by investigating these patterns it is possible to produce highly responsive interferometric sensors, e.g. for magnetic fields but also for gravitation. For the manipulation und excitation of condensates light is used. All Bose-Einstein condensates produced so far worldwide have a common disadvantage: Their broad optical transitions do not allow any precision excitations. In the case of Bose-Einstein condensates from alkaline earth atoms (e.g. calcium and strontium, both of which are being investigated at PTB as to their suitability as optical clocks) their super-narrow optical transitions offer novel potential for precision investigations. Conceivable is their use on satellites, e.g. by geophysicists, who study the deformation of the Earth and thus the change in gravitation.
At PTB it was possible for the first time worldwide to produce a Bose-Einstein condensate from alkaline earth atoms. To this end, 2·106 calcium atoms precooled in a magneto-optical trap were loaded at a temperature of 20µK into optical forceps. Due to the weakening of the holding force hot atoms vaporize, whereby the remaining atoms are cooled. At a temperature of typically 200 nK the critical temperature is reached with 105 atoms. Of these, approx. 2·104 atoms can be cooled to form a pure condensate.
Imke Frischmuth | alfa
APEX takes a glimpse into the heart of darkness
25.05.2018 | Max-Planck-Institut für Radioastronomie
First chip-scale broadband optical system that can sense molecules in the mid-IR
24.05.2018 | Columbia University School of Engineering and Applied Science
A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.
The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
24.05.2018 | Ecology, The Environment and Conservation
24.05.2018 | Medical Engineering
24.05.2018 | Physics and Astronomy