Cottrell Scholar Awards - 2017
Measuring Nanoscale Thermal Transport with Chains of Trapped Ions
Improvements in fabrication and materials processing have led to ever-smaller microelectronic devices and other structures of only a handful of atoms in size. But in achieving these miracles of miniaturization, scientists and engineers have run into a major problem: the crossover between ballistic and diffusive heat transport.
Any mechanism that does work gives off heat as a byproduct. For many devices, removing this waste heat is essential for continuous operation. Making things work at the incredibly tiny nanoscale requires a precise understanding of how that heat is dissipated. And yet, thermal conduction - a phenomenon familiar on macroscopic scales to anyone who has burned a finger on a hot dish - is poorly understood at the quantum mechanical level relevant for atomic-scale heat flow.
Charlie Doret, an assistant professor of physics at Williams College, has received a prestigious Cottrell Scholar Award from Research Corporation for Science Advancement (RCSA) to address fundamental questions about the quantum-to-classical transition for heat transport using chains of trapped calcium ions (positively charged calcium atoms).
In Doret’s research, ions will be trapped using electric fields to form a “string,” reminiscent of a string of pearls. Focused lasers will heat/cool the ions at each end of the string such that heat will flow along the chain, much as it would along a metal bar with one end in an oven and the other in a bucket of ice water. Additional lasers will non-invasively probe the average vibrational energy of individual ions in the string (their “temperature”), allowing for accurate measurements of the transition from classical to quantum heat transport as the string of ions is perturbed.
The Cottrell Scholar Award also promotes innovation in science education. Doret will use some of the funding to restructure a first-year course in modern physics to incorporate guided small-group problem-solving sessions.
“These sessions, which will replace a portion of the class time traditionally spent in lecture, will ensure all students have opportunities for regular few-on-one interactions with their instructors,” he said, adding he and his colleagues will also add a guided introduction to computational software during laboratory periods. In so doing he hopes to directly address differences in quantitative skills preparation and familiarity with computers among incoming students.