TRANSPORT PHENOMENON IN LOW-DIMENSIONAL SYSTEMS COUPLED AT THE NANOSCALE

Owing to their reduced phase-space enhancing electron-electron interactions, low-dimensional systems have been a fertile ground for the study of novel quantum phenomenon, especially when both inter-circuit and intra-circuit interactions are relevant.  In this talk, I will describe the fabrication techniques and experimental considerations required to couple and probe both 2D and 1D systems at the nanoscale, highlighting some of the key results that have observed in my group and their potential impact in the field of quantum information science.  In closely separated Si/SiGe bilayers, we observed the emergence of quantum Hall states associated with the layer degree of freedom.  By measuring the quantum Hall excitation gap at total filling fraction ?_T = 1 and ?_T = 2, we observed anomalous behavior for valley splitting as well as signatures of exciton condensation in this novel material system.  We also measured Coulomb drag in laterally coupled GaAs quantum wires. In the quasi-1D regime, the drag signal was found to be nearly independent of the current direction, thereby violating Onsager’s relation. This observation suggests that rectification of energy fluctuations plays an essential role for the onset of Coulomb drag between quasi 1D-systems.  Finally, I will expand on how these experiments pave the way towards the discovery of novel quantum states to improve future qubit systems.