Colloquium
by
Prof. Sir Michael Pepper
Pender Chair of Nanoelectronics,
University College London, UK
3 pm, 6th Nov, 2023 (Monday)
Title: Interactions, Fractionalization and Localization in 1-D and Quasi 1-D
Abstract:
Conductance quantization in semiconductor nanostructures is well-known when the electrons are strongly confined to 1D. Scattering is reduced and the system is in the regime of ballistic transport. However there has been much less investigation of the regime when the confinement is reduced and electrons are allowed to relax in the second dimension. As has been predicted, we have observed a level crossing as when a channel is wide the electron-electron interaction becomes more significant in determining energy levels than the spatial quantization. We have found that just before the transition to 2D a number of fractional plateaus of conductance are found, in the absence of a magnetic field in both Ge and GaAs. This phenomenon occurs when the electron-electron interaction determines the energies of the confined states and the ground state wavefunction changes its nature. The dependence of the quantization on the disorder will be discussed and the relationship for possible models of the process, which are based around an interaction-produced level separation, and an entanglement between the levels, which is accompanied by a coherent back-scattering.
Speaker
BIOGRAPHY:
Prof Michael Pepper is among the pioneers of Quantum Hall physics and conductance quantization phenomena in lower dimensions. He has been an active scientist for over 50 years with major contributions to academia and advanced technology industry.
He began his scientific career in the laboratories of Plessey electronics and GEC in late 1960s. He moved to the Cavendish laboratory of Cambridge University at the invitation of Nevil Mott. There he founded the Semiconductor Physics group in early 1980s and nurtured it for over 25 years. This group developed some of the key techniques that form the building blocks of nano electronics with low-dimensional systems and continues to be very well-known in this field. [This group authored approximately 200 papers in Physical Review Journals in the area of Semiconductor Physics.]
In 2007, he moved to University College London, as the Pender professor of Nanoelectronics. For several years he was also the managing director of Toshiba-Cambridge Research Laboratory (working on quantum communication technologies) and Terraview (medical imaging using terahertz radiation). His contributions have been recognized by The Royal Society (Hughes medal, Bakerian prize), The European Physical Society (Europhysics prize), The Institute of Physics (Guthrie & Mott prize) and a knighthood in 2006.
Venue: PC Saxena Auditorium, IIT Bombay
