CM Seminar- “Sensing New Quantum Limits at the Atomic Scale: from dynamical Coulomb blockade to superconducting quantum interference” with Dr. Christian R. Ast (Max Planck Institute for Solid State Research, Germany)
Physics Seminar
March 13, 2025
10:00 AM - 11:00 AM
Location
SES 2214
Calendar
Download iCal File"Sensing New Quantum Limits at the Atomic Scale: from dynamical Coulomb blockade to superconducting quantum interference"
Christian R. Ast
Max-Planck-Institut für Festkörperforschung, Stuttgart
The inherent quantum limit and hallmark of scanning tunneling microscopy (STM) has always been the ability to resolve single atoms on surfaces. A closer look, however, reveals many more quantum limits to be explored, when reducing system size, temperature, number of transport channels, and more. Lowering the temperature into the mK regime, exposes the quantized nature of the charge, which manifests itself in the interaction with the local environment during tunneling known as dynamical Coulomb blockade. Now placing a single spin system onto a superconducting surface induces Yu-Shiba-Rusinov (YSR) states due to the exchange interaction between spin and host. YSR states present a unique realization of protected single energy levels in a many-body environment, which makes them an excellent nanoscale playground. In my presentation, I will discuss the dynamics of YSR states in an interacting tunnel junction: How can we realize the smallest tunnel junction between two single energy levels? How can we realize the smallest superconducting quantum interference device to probe the otherwise elusive ground state of a YSR state? The answers comprise an intricate interplay of interactions in equilibrium and during tunneling, so that the dynamical Coulomb blockade becomes an integral part of the experiment. Our work has not only led to a better understanding of YSR states, but also tunneling in a dissipative environment at low temperatures in general.
Date posted
Mar 4, 2025
Date updated
Mar 11, 2025