Breakthrough of the Year

heat engine
The vacuum chamber where the atom trap is located (Image: Johannes Roßnagel)

Together with colleagues from Universität Mainz and Universität Kassel, FAU researchers have built the world’s smallest heat engine: the tiny engine consists of just one atom and is able to effectively transform heat into power. The British magazine Physics World included the researchers’ invention in its ‘Top Ten Breakthroughs of the Year’.

Just a few millimetres

The researchers at the three universities applied the principles of traditional heat engines, which are used, for example, to power motor vehicles, to a single electrically charged calcium atom. The particle is held in the air by four metal rods that are just a few millimetres long. An electrical noise signal causes the atom to oscillate strongly, making it heat up. In the second step the atom is cooled again by slowing its movements.

Starting the engine

To achieve this, the researchers fired a laser beam at the atom. Heating and cooling the atom causes it to oscillate – a movement that is comparable to the back-and-forth motion of the pistons in a conventional engine. Each heating and cooling cycle increases the atom’s oscillation radius, causing it to store energy. The development of nanomotors is particularly important for basic research as it allows researchers to learn more about the thermodynamics of individual particles – a key area of current research.

Among the ‘Top Ten Breakthroughs’ of 2016

The researchers’ next goal is to cool the atom even more to investigate thermodynamic quantum effects. According to Physics World, this experiment could open the door to research on the relationship between thermodynamics and quantum mechanics – which is why the magazine considers the work of the FAU researchers and their colleagues to be among the top ten breakthroughs of 2016.

Every year the renowned magazine, which is published by one of the largest societies for the study of physics, the Institute of Physics, honours the ten most important discoveries in the field. In 2013, FAU astrophysicists’ discovery of high energy cosmic neutrinos was named a breakthrough of the year. The ten selected projects are chosen according to criteria including the fundamental importance of the research, significant advance in knowledge, a strong connection between theory and the experiment, and the general interest for the field overall.