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Eiffel tower

A view of molecular electron wavefunction through atomistic geometry of a QD bilayer. Read full article at nanotechweb

Eiffel tower

"An Elemental Change to Laser Design"(Digital copy of article is here)


      Muhammad Usman

          Center for Quantum Computation & Communication Technology
          School of Physics, University of Melbourne
          Parkville, 3010, Melbourne
          VIC, Australia
          Center address: http://cqc2t.org
          Email: usman (at) alumni (dot) purdue (dot) edu




Research Areas:

Theoretical Condensed-Matter Physics
High Performance Computing
Optoelectronics
Quantum Computing


Education & Affiliations:

Ph.D. Electrical Engineering
Purdue University, West Lafayette Indiana, USA.

M.Sc. Electrical Engineering
University of Engineering & Technology, Lahore Pakistan.

B.Sc. (Honors & Distinction) Electrical Engineering
University of Engineering & Technology, Lahore Pakistan.

I am a member of the APS, MRS, IEEE, NCN, and Purdue Alumni Association.


Some of my talks are available online at nanoHUB.org:

[Video] Quantum Dot based Photonic Devices @ Physics Department, Dartmouth College, New Hampshire, USA

[Audio] Multi-layer QD Stacks for SOAs @ 3rd International Workshop on Epitaxial Growth and Fundamental Properties of Semiconductor Nanostructures, Austria

[Audio] Excited State Spectroscopy of a Bilayer QD Molecule @ Electrical & Computer Engineering Department, University of Iowa, Iowa, USA

[Audio] Theory of Bismide Alloys @ 2nd International Workshop on Bismuth containing Semiconductors, Surrey University, UK

[Audio] Why QD Simulations Must Contain Multi-Million Atoms?  

[PDF] PhD Research Summary @ Purdue University, Indiana, USA

[PDF] Quantum Dots - My PhD Thesis @ Purdue University, Indiana, USA


Research Interests:

I work in multi-disciplinery area of research involving rigorous knowledge of nano-electronics, condensed-matter physics, computational physics, etc. Overall, I am interested in all aspects of light matter interaction. My research work is aimed at improving the efficiency of the energy-conversion devices (photovoltaics), wavelength and polarization engineering by studying novel nano-materials for telecomm and infra-red range devices, and quantum information science in coupled quantum dot systems.

More specifically, I work on the theory, modeling, and simulation of semiconductor materials, their alloys, and low-dimensional devices.

My past and ongoing research efforts are motivated to seek answers for the following questions:

  • Can we design efficient photonic devices from quantum dots? How can we engineer QD parameters to tune output wavelength and polarization for a desired operation?

  • How can bismuth (Bi) based alloys such as GaBiNAs, InGaBiAs, etc. help to realize highly efficient telecomm wavelength devices with reduced temperature sensitivity and supressed Auger losses?

  • How to implement qubit operation in a coupled quantum dot system via coherent manipulation of the trapped charges or spin?

  • To understand and resolve efficiency impeding mechanisms in nanomaterial based photovoltaics to realize sustainable, ecnomical, efficient, and green energy solutions

  • My theory and modeling work is based on the following methods:

  • Strain relaxation based on atomistic valence force field method.

  • Electronic structure calculations based on sp3d5s*/sp3s* tight-binding method, k.p model, density functional theory, or some hybrid of these methods.

  • Interband optical transition strengths from the Fermi's Golden rule.

  • Linear and quadratic piezoelectric potentials by solving the Poisson's equation.

  • Many-body excitonic spectra by Hartree-Fock (HF) approximation, Configuration Interaction (CI) approach.

  • The detials about these methods are presented here: Modeling Methodologies   



                                                  Last updated: August 2012, (best viewed in chrome browser), copyright © Muhammad Usman, all rights reserved.