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Engine from one atom
In its current issue, the science magazine Science reports on a new type of heat engine that works with just a single atom. The experiments were set up under the direction of Prof. Dr. Kilian Singer, head of the Department of Experimental Physics I at the University of Kassel, during his time at Johannes Gutenberg University Mainz (JGU) and carried out in collaboration with theoretical physicists from the University of Erlangen-Nuremberg.
Since the industrial revolution, heat engines have played a decisive role in our society. They convert thermal energy into mechanical work, for example in vehicles, and have become an integral part of modern life. At the same time, miniaturization is leading to ever smaller technical devices.
The scientists working with Prof. Dr. Kilian Singer use a so-called Paul trap to store a single, electrically charged calcium atom. The atom can be heated by electrical noise and cooled by laser beams. As a result, it undergoes a thermodynamic cycle, comparable to the processes in the cylinder of a classic engine. The power generated is converted into an oscillation of the atom. The atom thus plays the role of both the engine and the energy store.
The physicists were able to characterize the thermodynamic behaviour of the engine in extensive series of measurements. As the researchers now show in their publication, the single-atom motor delivers an output of 10-22 watts and has an efficiency of 0.3 percent. If the power of the single-atom engine is standardized to the small mass of an atom, its performance is comparable to that of a car engine. "By reversing the cyclic process, we can operate the machine as a single-atom refrigerator and use it to cool coupled nanosystems," says Johannes Roßnagel, first author of the study.
What is particularly important about this research, however, is that the realization of such a nanomotor allows an insight into the thermodynamics of individual particles, a highly topical field of research. In future, the plan is to further reduce the working temperature of the machine and investigate thermodynamic quantum effects. Theoretical work has suggested increasing the performance of a heat engine by coupling it to a quantum bath. This opens up a wide range of possibilities for going beyond the paradigms of classical thermodynamics and building new types of engines.
The project was funded by the German Research Foundation as part of the "Single Ion Heat Engine" project and by the Volkswagen Foundation as part of the "Atomic Nanoassembler" project.
Publication:
Johannes Roßnagel et al.
A single-atom heat engine
Science, 15. 4. 2016
DOI: 10.1126/science.aad6320
Images:
http://www.uni-mainz.de/bilder_presse/08_physik_quantum_ein_atom_motor_01.jpg
View of the vacuum chamber with the trap (center). Photo: AG Quantum, JGU Mainz
http://www.uni-mainz.de/bilder_presse/08_physik_quantum_ein_atom_motor_02.jpg
Part of the laser system that alternately cools and heats the atom. Photo: AG Quantum, JGU Mainz
Photo by Johannes Rossnagel. Photo: Private
Further information:
Prof. Dr. Kilian Singer
University of Kassel
Experimental Physics I / Light-Matter Interaction
Phone +49 561 804-4235
E-mail: ks[at]uni-kassel[dot]de
Further links: