Paired Electron Additions to Fractional Quantum Hall Edge States in Large GaAs Quantum Dots
ORAL
Abstract
Using single electron capacitance spectroscopy, we determine the energies required to add single electrons to a large (0.8 μm) 2D GaAs quantum dot. We observe capacitance peaks from electron additions to edge states over a wide range of Landau level filling factors. As a function of magnetic flux through the dot, between filling factors ν = 1 and ν = 2, these peaks are regularly spaced with periodicity h/e. Surprisingly, over the range ν = 2 to ν = 5, the peaks double in height and form exact pairs. In this regime, the mean periodicity of capacitance peaks is halved to h/2e, indicating the addition of four electrons to the edge for each flux quantum threading the dot. Remarkably, these pairs themselves bunch together at all filling factors except those close to ν = 5/2. The observed pairing violates the Coulomb blockade picture in which a charging energy would separate the two electron peaks that comprise a pair. Instead the sequence of successive paired tunneling events behaves in the same way as tunneling of electrons into superconducting quantum dots.
*Supported by the DOE Office of Science BES, FG02-08ER46514, and the Gordon and Betty Moore Foundation, GBMF2931. S. Aronson supported by NSF Graduate Research Fellowship Program, Grant No. 1122374.
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Presenters
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Samuel Aronson
- Physics, Massachusetts Institute of Technology