Non-equilibrium Fluctuations of Vacuum Trapped Nanoparticles

Christoph Dellago (University of Vienna) and Lukas Novotny (ETH Zurich) With the breathtaking progress we have witnessed during the past decades in method- ologies to manipulate and precise control of matter at the atomic and molecular level, the construction of nanomachines is now within technological reach, promising a vast range of new applications potentially affecting many facets of our lives. Such machines, however, work under completely different conditions than those we are used to in our macroscopic world on the human scale, where friction can usually be reduced to keep energy losses low. Just as the molecular motors working in our cells, nanomachines are typically strongly cou- pled to their environment and exposed to continuous buffeting from the atoms of the liquid or gaseous substances surrounding them. As a consequence, such devices do not follow the deterministic laws of mechanics and thermodynamics and the randomness due to irregular thermal motion plays a much stronger role than in more traditional fields of engineering. Thus, nanoscopic machines evolve stochastically and this element of chance must be taken into account in their design and analysis. From a theoretical perspective, much progress in our understanding of how nano- systems behave has been made through the development of so-called fluctuation theorems, which specify how frequently certain random deviations from the average behavior occur when the system is driven away from equilibrium. In particular, these theorems specify the likelihood of apparent transient violations of the second law of thermodynamics, one of the cornerstones of physics, and, hence, shed new light on the meaning of irreversibility and dissipation at the nanoscopic level. In this joint project between the University of Vienna and the ETH Zurich, we will use the tools of stochastic thermodynamics, the theory developed to describe the exchange of heat and work in small systems, to investigate the non-equilibrium dynamics of a nanoparticle captured in a laser trap. In this light cage, the nanoparticle can be manipulated in a very controlled way by the minute forces exerted on the particle by the la- ser. Using this laboratory experiment, we will investigate the significance of the second law of thermodynamics in the nanoworld and its consequences for the operation of nanomachines and the physical limits of information processing devices.

Non-equilibrium Fluctuations of Vacuum Trapped Nanoparticles Christoph Dellago (University of Vienna) and Lukas Novotny (ETH Zurich) With the progress of methodologies to manipulate microscopic matter during the last decades the construction of nanomachines is now within technological reach, promising a vast range of new applications potentially affecting many facets of our lives. Such machines, however, work under completely different conditions than those we are used to in our macroscopic world, where friction can usually be reduced to keep energy losses low. Just as the molecular motors working in our cells, such nanomachines are typically strongly coupled to their environment and exposed to continuous buffeting from the atoms of the liquid or gaseous substances surrounding them. As a consequence, such devices do not follow the deterministic laws of mechanics and thermodynamics and the randomness due to irregular thermal motion plays a much stronger role than in more traditional fields of engineering. Thus, nanoscopic machines evolve stochastically and this element of chance must be taken into account in their design and analysis. In a joint project funded by the Austrian FWF and the Swiss SNF, researchers from the University of Vienna and the ETH Zurich have now used nanoparticles trapped with laser lights to study the fundamental properties of such nanosystems. In particular, they have succeeded in demonstrating that adding friction can speed up transitions between long-lived states of nano-systems. Moreover, the researchers investigated how the speed of such transitions can be controlled with active propulsion forces as they are used, for instance, by micro-organsism to move around. The results of this project may help to design more efficient nanomachines and to further the understanding of active transport in microbiology.