Classical Statistical Mechanics Using Confined Brownian Particles

The understanding of statistical physics at the mesoscopic scale inside fluidic environments is crucial – most importantly, since the processes which determine the functioning of life itself work at this scale in similar environments. Studying such processes under controlled conditions in the laboratory is thus the starting point in tackling more complex problems involving actual mechanisms that generate life. The advent of micro-particle confinement techniques using optical, electric or magnetic fields has enabled diverse research in this area with the help of single or multiple particles that are confined in well-calibrated force fields. In addition, the ability to introduce external forces facilitate scenarios where particles may be in equilibrium or out of equilibrium with the fluidic environment. Within such an approach, tenets of both equilibrium and non-equilibrium statistical mechanics may be tested, and existing theories may need to be extended in order to understand experimental results. The presence of interactions between particles, as well as those between the particle(s) and the fluid, lead to even more complex physics and may thus simulate a variety of life processes. Moreover, recent efforts have also been successful in confining nanoparticles in near-vacuum conditions, so as to increase the scope of such experiments towards research in statistical physics. Advanced microfabrication techniques and clever experimental designs enabling the creation of nanorobots able to perform work have indeed shown the promise of several important applications including diagnostics, drug delivery, and therapeutics. However, the understanding and calibration of the nanorobots invariably imply a thorough study of the statistical physics governing their activity, which can only be performed with the help of advanced experimental techniques. To this end, there has been tremendous progress among techniques ranging from the use of advanced high-speed electronics to adaptive optics. These techniques enable the application of large trapping forces as well as very precise detection of particle dynamics to picometer scales. Very recently, machine learning techniques are also being developed to calibrate and measure particle dynamics and force fields with very high precision to facilitate more accurate measurements.

In light of the significant research advancement in this area, we believe that a Research Topic is called for. We would like to invite contributions from scientists engaged in active research in areas which may include (but are not be limited to):
- The study of statistical mechanics of Brownian particles confined in equilibrium and non-equilibrium conditions in fluids
- Active and living matter
- Particles trapped in air or vacuum
- Collective motion of particles and synchronization
- Brownian engines
- Interactions between Brownian particles and simple/complex fluids
- Advanced experimental techniques facilitating precise measurements of particle dynamics
- Calibration and data analysis techniques facilitating accurate statistics.

We hope that this Research Topic will contribute positively to the growth of the field and enable researchers to obtain a lucid overview of the cutting-edge research that is being carried out in this area.