PRISM Seminar Series- Hari Manoharan
05/07/08
Hari Manoharan
Supersymmetric Quantum Nanostructures
Stanford University
Physics
Abstract:
Embedded into the topology of our universe lurks a subtle yet far-reaching spectral ambiguity. There exist drum-like manifolds of different shape that resonate at identical frequencies, making it impossible to invert a measured spectrum of excitations into a unique physical reality. An ongoing mathematical quest has recently compacted this conundrum from higher dimensions to planar geometries. Inspired by these isospectral domains, we introduce a class of quantum nanostructures characterized by matching electronic structure but divergent physical structure. We perform quantum measurements (scanning tunneling spectroscopy) on these “quantum drums” (degenerate two-dimensional electrons confined by individually positioned molecules) to reveal that isospectrality provides an extra topological degree of freedom enabling the mapping of complete electron wavefunctions—including all internal quantum phase information normally obscured by direct quantum measurement.
The robustness of the technique stems from its connection to supersymmetric quantum mechanics, where inequivalent “superpartner” Hamiltonians produce equivalent energy spectra. The methods are general and extensible to other nanostructures and fabrication techniques, and we have recently used variants of these ideas to experimentally detect superposition phase and the Berry phase.
In these experiments we utilize the exciting technology of atomic and molecular manipulation: a custom-built scanning tunneling microscope, operating at low temperature in ultrahigh vacuum, is used to assemble nanostructures atom-by-atom to generate versatile quantum laboratories at the spatial limit of condensed matter.
About Hari Manoharan:
“My research program seeks to apply the "bottom-up" approach of atomic and molecular manipulation to a variety of outstanding problems in science and technology. The effort is interdisciplinary in nature, centering on physics and engineering but involving ideas, techniques, and conundrums from other fields such as chemistry, biology, materials science, and information technology. The primary experimental apparatus for these investigations are custom-built low-temperature scanning probe microscopes capable of both studying and controlling matter at atomic length scales.”
Research projects, whose motivations are drawn from several research frontiers, include:
- Nanoassembly using Atomic and Molecular Manipulation
- Studies of Isolated and Interacting Magnetic Moments
- Local Probes of Correlated Electrons in Reduced Dimensions
- Local Response of Novel Superconductors
- Exploring New Paradigms in Computation
- Atomic and Molecular Electronics
- Organic Molecules and Interface to Life
My research group:
Our research fields:
Career History
- B.S.E. Princeton University (1991).
- M.S. Stanford University (1992).
- M.A. Princeton University (1993).
- Ph.D. Princeton University (1997).
- Research Scientist, IBM Almaden Research Center (1998-2000).
- Assistant Professor of Physics, Stanford University (2001-present).
- Assistant Professor, by Courtesy, of Electrical Engineering, Stanford University (2001-present).
- Assistant Professor, by Courtesy, of Materials Science and Engineering (2001-present).