Steve Simon

Abstract:

An experimental study of a Fabry-Perot interferometer in the quantum Hall regime reveals Aharonov-Bohm-like (ABL) oscillations. Unlike the Aharonov-Bohm effect, which has a period of one flux quantum, Φ0, ABL oscillations possess a flux period of Φ0/f, where/is the integral value of fully filled Landau levels in the constrictions. The detection of ABL oscillations is limited to the low magnetic field side of the vc = 1, 2, 4, 6,..., integer quantum Hall plateaus. These oscillations can be understood within the Coulombdominated model of quantum Hall interferometers as forward tunneling and backscattering, respectively, through the center of the interferometer from the bulk and the edge states. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Abstract:

We perform numerical studies to determine if the fractional quantum Hall state observed at a filling factor of ν=5/2 is the Moore-Read wave function or its particle-hole conjugate, the so-called anti-Pfaffian. Using a truncated Hilbert space approach we find that, for realistic interactions, including Landau-level mixing, the ground state remains fully polarized and the anti-Pfaffian is strongly favored. © 2011 American Physical Society.

Abstract:

Based on the known physics of the excitonic superfluid or 111 state of the quantum Hall ν = 1/2 + 1/2 bilayer, we create a simple trial wavefunction ansatz for constructing a low-energy branch of (Goldstone) excitations by taking the overall ground state and boosting one layer with respect to the other. This ansatz works extremely well for any interlayer spacing. For small d, this is simply the physics of the Goldstone mode, whereas for large d, this is a reflection of composite fermion physics. We find hints that certain aspects of composite fermion physics persist to low d whereas certain aspects of Goldstone mode physics persist to high d. Using these results, we show nonmonotonic behavior of the Goldstone mode velocity as a function of d. Copyright 2011 Gunnar Mller and Steven H. Simon.