Interaction matrix element fluctuations in quantum dots
- Department of Physics, Tulane University, New Orleans, LA 70118 (United States)
- Center for Theoretical Physics, Sloane Physics Laboratory Yale University, New Haven, CT 06520 (United States)
In the Coulomb blockade regime of a ballistic quantum dot, the distribution of conductance peak spacings is well known to be incorrectly predicted by a single-particle picture; instead, matrix element fluctuations of the residual electronic interaction need to be taken into account. In the normalized random-wave model, valid in the semiclassical limit where the number of electrons in the dot becomes large, we obtain analytic expressions for the fluctuations of two-body and one-body matrix elements. However, these fluctuations may be too small to explain low-temperature experimental data. We have examined matrix element fluctuations in realistic chaotic geometries, and shown that at energies of experimental interest these fluctuations generically exceed by a factor of about 3-4 the predictions of the random wave model. Even larger fluctuations occur in geometries with a mixed chaotic-regular phase space. These results may allow for much better agreement between the Hartree-Fock picture and experiment. Among other findings, we show that the distribution of interaction matrix elements is strongly non-Gaussian in the parameter range of experimental interest, even in the random wave model. We also find that the enhanced fluctuations in realistic geometries cannot be computed using a leading-order semiclassical approach, but may be understood in terms of short-time dynamics.
- OSTI ID:
- 21136989
- Journal Information:
- AIP Conference Proceedings, Vol. 995, Issue 1; Conference: WNMP 2007: Workshop on nuclei and mesoscopic physics, East Lansing, MI (United States), 20-22 Oct 2007; Other Information: DOI: 10.1063/1.2915599; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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