Title: Visualizing Quantum Waves

Speaker: Rahul Sharma, Cornell University, USA

Abstract: The quasiparticles in a condensed matter system are the eigenstates of the Hamiltonian, providing a direct window into the physics of the system.The impurity potentials generated by disorder in a material causes Friedel oscillations of quasiparticles : “Quantum Waves” . In this discussion, I will describe the spectroscopic imaging scanning tunneling microscope (SI-STM) which allows us to image these quantum waves which unravels physics in both real and reciprocal space. In particular I will present two puzzles we have addressed: 1) Sr2RuO4 has been long touted as a topological superconductor, why then no protected edge currents have been observed in ultra-sensitive experiments? 2)The origin of Cooper pairing in iron-based superconductors is still under debate. The symmetry of the superconducting order parameter is an important quantity which can shed some light on this issue. Usual experimental tools can measure only the magnitude of the gap(order parmeter) symmetry. Is there a way to determine the gap symmetry, in both magnitude and sign?