Feb 13, 2020 3:45 pm - Nielsen Hall 170 (Neal F. Lane Auditorium) - Colloquium
Nicholas Laurita - Caltech
Shining Light On Quantum Materials

Despite quantum mechanics being the governing principles of all materials at the microscopic scale, macroscopic measurements of material properties nearly always give classical results. Recently, a surge of interest has been devoted to “quantum materials,” where non-trivial topology and entanglement drive materials to exhibit macroscopic quantum phenomena. At one end of the quantum materials spectrum lies strongly correlated magnetic insulators, which have been theorized to form highly unusual quantum phases with fractionalized quasi-particles that are potentially beneficial for quantum computation. However, a microscopic understanding of these materials is lacking, in part due to the many-body nature of spin-Hamiltonians but also due to the hindrance of typical techniques for probing dynamic magnetic responses. In this talk, I will demonstrate how a suite of equilibrium and ultra-fast optical techniques are uniquely suited to probe and control strongly correlated quantum matter. As examples, I will focus on two material systems: First, I will demonstrate how the low-energy linear response of FeSc2S4 naturally encodes signatures of a unique long-ranged entangled "spin-orbital liquid" ground state that is on the edge of quantum criticality. Then, I will detail how non-linear optical techniques can be implemented to uncover the hidden nematicity of the ground state of the prototypical Kagome spin-liquid candidate Herbertsmithite ZnCu3(OH)6Cl2. Together, these results embody the unique promise that optical techniques hold in the emerging quantum materials research forefront.