Phononics: Manipulating heat flow with electronic analogs and beyond

TL;DR

This paper explores how phonons, traditionally seen as waste heat, can be manipulated like electrons and photons to control heat flow and process information, leading to innovative nanoscale thermal devices and phenomena.

Contribution

It introduces electronic analogs for phononic devices, demonstrating control of heat transport and information processing with practical designs and experimental realizations.

Findings

Development of thermal diodes, transistors, and logic gates

Design of hybrid nanostructures for heat control

Observation of heat shuttling and phonon Hall effect

Abstract

The form of energy termed heat that typically derives from lattice vibrations, i.e. the phonons, is usually considered as waste energy and, moreover, deleterious to information processing. However, with this colloquium, we attempt to rebut this common view: By use of tailored models we demonstrate that phonons can be manipulated like electrons and photons can, thus enabling controlled heat transport. Moreover, we explain that phonons can be put to beneficial use to carry and process information. In a first part we present ways to control heat transport and how to process information for physical systems which are driven by a temperature bias. Particularly, we put forward the toolkit of familiar electronic analogs for exercising phononics; i.e. phononic devices which act as thermal diodes, thermal transistors, thermal logic gates and thermal memories, etc.. These concepts are then put to work to transport, control and rectify heat in physical realistic nanosystems by devising practical designs of hybrid nanostructures that permit the operation of functional phononic devices and, as well, report first experimental realizations. Next, we discuss yet richer possibilities to manipulate heat flow by use of time varying thermal bath temperatures or various other external fields. These give rise to a plenty of intriguing phononic nonequilibrium phenomena as for example the directed shuttling of heat, a geometrical phase induced heat pumping, or the phonon Hall effect, that all may find its way into operation with electronic analogs.