Chemical Engg. Seminar Series : Dr. Rousan Debbarama

Parallel Quantum Dots as Artificial Atoms: Insights from Electron Transport Measurements.

Quantum dots, often referred to as artificial atoms, can be coupled to form artificial molecules with properties that can be exploited for emerging quantum technologies. These coupled quantum dots exhibit phenomena analogous to those seen in atomic and molecular physics and chemistry, such as Hund’s rule and orbital hybridization.

In my talk, I will show how electrical transport measurements can be used as a spectroscopic tool to characterize quantum dots and probe the interactions between the orbitals of two dots in a coupled quantum dot system. In the first part of my talk, I will discuss how quantum rings with different symmetries can be realized by controlling the orbital parities of the individual dots in a double quantum dot (DQD) system, analogous to Hückel’s theory of aromaticity. In these ring states, the electrons gain exceptionally large orbital angular momentum [1].

Next, I will present what happens when we place the DQD system between two superconducting contacts, forming a Josephson junction [2]. This configuration allows the study of how spin and orbital states influence the supercurrent or Cooper pair transport. Finally, I will show how we can study the current-phase relationship of the Josephson junction by embedding the DQD in a superconducting quantum interference device (SQUID) [3].