Interactions can lead to a wide variety of ordered states in quantum materials. For this talk, I will focus on the case of high rank multipole order of local atomic states. I will particularly emphasize the importance of coupling to the associated order parameters as a means to measure the multipolar susceptibilities, and also, inside the ordered state, to induce quantum fluctuations via application of transverse effective fields. I will explain the very special roles that strain can play for each of the cases (quadrupolar, octupolar, hexadecapolar), and will outline new experimental approaches in which the materials 'feel the strain' in different ways. Along the way I will introduce a special case of an electro-nuclear quantum phase transition that I am especially excited by. The confluence of new measurement techniques and new materials also leads to possibilities for new applications; if time allows, I will briefly outline one such application, based on a giant elastocaloric effect. Multipolar order, it would seem, is not only interesting from a fundamental perspective, but can also be useful.
Ian Fisher is a Professor of Applied Physics at Stanford University, working in the general area of experimental condensed matter physics. In recent years, his research has emphasized novel ways in which externally induced strains can be used to couple to and manipulate a variety of exotic electronic states, revealing essential aspects of their causes and consequences.