Sumathi Rao


Research Summary:

I have mainly been working in the area of electronic transport in quantum wires and quantum dots. The aim is to compute conductances in these low-dimensional systems. Earlier work has mainly focussed on using the non-interacting single particle approach to these problems. Our aim has been to include inter-electron interactions and since much of our work is in one-dimension, we use Luttinger liquid theory and the formalism of bosonisation.

We generalised the two-terminal junction of interacting quantum wires to $N$-terminals and showed that the renormalisation group flow and fixed point structure of the $S$-matrix for $N\ge 3$ is quite non-trivial and leads to several interesting experimental possibilities.

We have also worked on tunnel-coupled quantum dots and capacitively coupled quantum dots and obtained the pattern of conductances as a function of the gate voltages controlling the number of electrons in each dot. This agrees with the experimental results in the tunnel-coupled case. For the capacitively coupled case, it is a prediction, since the specific experiment has not yet been done.

More recently, we have worked on adiabatic pumping of electrons through quantum dots and we have made interesting predictions for the behaviour of the pumped charge as a function of the number of dots through which the electrons are pumped.

Publications:

  • 1. Junction of several weakly interacting quantum wires: a renormalization group study, cond-mat/0206259. (with Siddharth Lal and Diptiman Sen), Phys. Rev. B66 (2002), 165327.

Preprints:

  • 1. Effective action and interaction energy of coupled quantum dots (with Sourin Das), cond-mat/0209033.

  • 2. Quantised charge pumping through multiple quantum dots ( with Argha Bannerjee and Sourin Das), cond-mat/0307324.

  • 3. Transport through multiply connected carbon nano-tubes ( with Sourin Das) in preparation.

  • 4. `Transport in quantum wires', presented at TH2002, July 2002, (Paris), to be published.


Conference/Workshops Attended:

  • 1. International Conference on Theoretical Physics, (22-27 July 2002) Paris, UNESCO.

  • 2. National Conference for Theoretical Physics, Indian Association for Cultivation of Science, (21-24 January), Kolkatta.

Visits to other Institutes:

  • 1. On sabbatical at Penn State University, State College, U.S.A, till August 31st, 2002.

  • 2. Dept of Physics, University of Montreal, Canada, May 4-8, 2002.

  • 3. Dept. of Physics (Condensed Matter Group), Masachussetts Institute of Technology, Boston, U.S.A, May 10-15, 2002.

  • 4. Dept. of Physics (Condensed Matter Group), Boston University, Boston, U.S.A May 17-24, 2002.

  • 5. Dept of Physics( Condensed Matter group), Cambridge University,
    Cambridge, England, June 8 - July 20, 2002.

  • 6. International Centre for Theoretical Physics, Trieste, Italy, August 10 - September 30, 2002.


Invited Lectures/Seminars:

  • 1. `Transport in Quantum wires' , specialised lecture in thematic session, International Conference on Theoretical Physics, TH2002, July 21-27, 2002, UNESCO, Paris. (2002).

  • 2. `Theoretical Physics in the Third World : An Indian perspective'
    International Conference on Theoretical Physics, TH2002, July 21-27, 2002, UNESCO, Paris. (2002)

  • 3. Transport through quantum dots', National Conference on Theoretical Physics, Indian Association for Cultivation of Science, January 21-24, 2003.

  • 4. `Transport in Mesoscopic systems', Colloquium at Tata institute of Fundamental Research, Feb 26, 2003.


Academic recognition/Awards:

  • 1. Elected Fellow of the National Academy of Sciences, Allahabad, India


Other Activities:

  • 1. Taught Quantum Field Theory II, January-May 2002, Penn State University, State College, U.S.A.

  • 2. Taught Statistical Mechanics, January-May 2003, HRI, Allahabad.

  • 3. Member of National Organising Committee, Statphys 22, to be held in Bangalore in July 2004.

  • 4. Member of the International Union of Pure and Applied Physics working group on `Women in physics'.

 



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