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            Eiffel tower

Supercomputers model real-world quantum dot devices atom-by-atom! Read full article here

                  Eiffel tower

Si:As Donor Wave Function - Fixing the Central-Cell Corrections in the Tight-binding Theory. (Complete article is here)

            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, VIC, Australia
          Center address: http://cqc2t.org
          Email: usman (at) alumni (dot) purdue (dot) edu

Research Areas:

Condensed-Matter Physics
High Performance Computing
Engineering Education

Education & Affiliations:

(2010-2014) Researcher, Tyndall National Institute, Cork Ireland.
(2005-2010) Ph.D. Electrical Engineering, Purdue University, West Lafayette Indiana, USA.
(2004-2005) M.Sc. Electrical Engineering, University of Engineering & Technology, Lahore Pakistan.
(1999-2003) B.Sc.(Honors & Distinction) Electrical Engineering, University of Engineering & Technology, Lahore Pakistan.

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] Theory of Self-Assembled Quantum Dots - My Ph.D. Thesis @ Purdue University, Indiana, USA

Research Interests:

I am an electrical engineer and a quantum physicist. I work in multi-disciplinery area of research, involving rigorous knowledge of nanoscale electronics, condensed-matter physics, quantum chemistry, and multi-scale computational modeling.

More specifically, my work is based on the theory, modeling, and simulations of semiconductor materials, their constituent alloys, and low-dimensional devices. I aim at exploiting the promising properties of semiconductors to design next-generation optoelectronic devices, photovoltaic devices, and more recently qubit devices.

My past and ongoing research efforts are motivated by some of the most exciting questions that have fascinated the condensed-matter physics community during the last few years, such as:

  • Exploiting the long coherence times of donor-silicon based qubit systems for quantum computing architectures

  • Designing the efficient photonic devices from the self-assembled quantum dots by engineering their output wavelength and light polarisation for a desired operation

  • Bismuth (Bi) based alloys such as GaBiNAs, InGaBiAs, etc. offer large spin-orbit coupling. Can we realize highly efficient telecomm wavelength devices from bismides that would offer reduced temperature sensitivity and suppressed Auger losses?

  • Understanding and resolving the efficiency impeding mechanisms in nano-material based photovoltaics to realize sustainable, economical, efficient, and green energy solutions

  • Research Methods:

    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.

  • Further details about these methods are presented here: Modeling Methodologies   

    1) Are you an experimentalist and interested in our theory? Please feel free to send an email.

    2) Are you a student and want to be a part of our team? Please feel free to send an email.
        For admission and scholarship information, please visit: http://futurestudents.unimelb.edu.au/admissions/scholarships

                                                  Last updated: August 2014, (best viewed in chrome browser), copyright © Muhammad Usman, all rights reserved.