Three Caltech Professors Named Fellows of the American Physical Society

Caltech professors Marco Bernardi, Sujit Datta, and John Sader have been named fellows of the American Physical Society (APS) for their outstanding contributions to physics.

Marco Bernardi, professor of applied physics, physics, and materials science and the undergraduate and graduate option representative for materials sciences, was nominated by the APS Division of Computational Physics (DCOMP). He studies quantum interactions and dynamics in matter, picking apart the processes that take place on the tiniest of scales—how individual electrons, units of vibration, or spins move and interact in semiconductors and quantum materials, for example. He begins from first principles to build theories and computational methods of making quantitative predictions about these behaviors that will inform the next generation of electronic, optical, magnetic, and quantum technologies.

The APS notes that Bernardi was nominated for "pioneering first-principles calculations of electron interactions, transport, and nonequilibrium dynamics in conventional and quantum materials, especially for electron–phonon interactions and polaron physics; and for the development of novel computational methods and software."

"I am truly honored to be recognized by my peers in DCOMP, and especially grateful to the wonderful students and postdocs whose talent, creativity, and hard work have made this journey possible," Bernardi says. "This milestone is both deeply meaningful and motivating; it inspires us to keep pushing the boundaries of computation to understand quantum interactions and dynamics in matter."

Sujit Datta, professor of chemical engineering, bioengineering, and biophysics, was nominated by the APS Division of Soft Matter Physics (DSOFT) for work that examines how environmental factors change the behavior of "squishy" materials, such as bacteria, mucus, and other polymeric fluids, and how these materials in turn affect their environments. His group uses a combination of experiments, theoretical modeling, and computer simulations to better understand the fundamental principles governing these systems and their potential applications.

According to the APS, Datta was honored for "bridging soft matter physics and biology in realistic settings to advance the quantitative understanding of the dynamics of complex fluids and bacterial suspensions in complex environments."

"APS has been my intellectual home since I was an undergraduate who was given the chance to join a physics lab two decades ago and fell in love with scientific discovery in the process," Datta says. "That joy still drives the work that my group and I do, and this recognition reflects their creativity and hard work. I owe a great deal to my trainees, collaborators, colleagues, and mentors over the years, as well as the broader soft-matter community, for supporting and inspiring me to follow curiosity across disciplines."

Datta subscribes to the credo of one of his intellectual heroes, John Hopfield, Caltech's Roscoe G. Dickinson Professor of Chemistry and Biology, Emeritus, and winner of the 2024 Nobel Prize in Physics. Datta describes physics as a point of view that the world around us is, with effort, ingenuity, and adequate resources, understandable in a predictive and reasonably quantitative fashion. "I look forward to many more years of exploring the world through that lens with this incredible community," he says.

John Sader, a research professor of aerospace and applied physics, was recognized by the APS Division of Fluid Dynamics (DFD). Over the course of his career, Sader, an applied mathematician with a graduate degree in electrical engineering, has tackled problems such as vortex flows in water and air (the swirling motions seen everywhere from draining bathtubs to aircraft wakes), as well as in more exotic systems, often in close collaboration with experimentalists. These systems include electrons that flow like a viscous fluid through graphene, a sheet of carbon only 1 atom thick, and superfluids that flow with zero viscosity, or no friction at all. His work also underpins precise measurements of the forces between individual atoms. He pioneered the Sader Method, which is widely used to calibrate atomic force microscopes. This method measures the stiffness of the tiny, springlike beam that holds the microscope's nanoscale tip by analyzing how the beam vibrates in air, so the delicate tip is never damaged.

The APS cited Sader for "pioneering contributions to fluid-structure interactions, including the Sader Method for atomic force microscopy, fundamental insights into vortex generation by airfoils, and analyses of Boltzmann transport for gaseous and electronic flows."

"I have been fortunate to work with exceptional students and collaborators from around the world, particularly experimentalists who have helped transform theoretical ideas into practical advances," Sader says. "It is especially gratifying to see the methods we have developed enable others to advance their own research."