Description:

Varada Bal -- “Gate-tunable Josephson junctions at the LaAlO$_3$ - SrTiO$_3$ interface”

Abstract: We demonstrate top-gate tunable Josephson junction like behaviour in the two dimensional electron gas at the LaAlO$_3$-SrTiO$_3$ interface. A combination of global back-gating and local top-gating is used to define the junctions, providing an efficient way for much finer spatial control over the properties of the interface, as compared to back-gating alone. The variation of the critical current and zero bias resistance with temperature shows that the junctions behave like short, overdamped weak links. These weak links can aid in illuminating the nature of superconductivity in the LaAlO$_3$-SrTiO$_3$ interface system. We show that the applied top-gate voltage provides a strong handle on the properties of the weak link. This technique can be an important tool to define a variety of device structures in this system, allowing us to probe it in different ways. 

Carl Rodriguez -- “Modeling Black Holes within Dense Stellar Clusters”

Abstract: Globular clusters are very old, gravitationally bound systems of stars found throughout the Milky Way and other galaxies.  Precision modeling of these systems can answer important questions about the formation, accretion, and dynamics of black holes across cosmic time.  Here at Northwestern, we have developed a code which enables us to simulate the dynamics of a globular cluster of up to 10 million stars in a few weeks.  I will describe the basis of this approach, as well as some recent work to more precisely model the dynamics of the black holes embedded within globular clusters.

Pizza will be available for $2/slice.