Interaction-induced interference in the integer quantum Hall effect

Abstract

In recent interference experiments with an electronic Fabry-Perot interferometer (FPI), implemented in the integer quantum Hall effect regime, a flux periodicity of h/2e was observed at bulk fillings > 2.5. The halved periodicity was accompanied by an interfering charge * = 2 , determined by shot noise measurements. Here, we present measurements, demonstrating that, counterintuitively, the coherence and the interference periodicity of the interfering chiral edge channel are solely determined by the coherence and the enclosed flux of the adjacent edge channel. Our results elucidate the important role of the latter and suggest that a neutral chiral edge mode plays a crucial role in the pairing phenomenon. Our findings reveal that the observed pairing of electrons is not a curious isolated phenomenon, but one of many manifestations of unexpected edge physics in the quantum Hall effect regime.Note that such "pairing" was not observed in a Mach-Zehnder interferometer (MZI) (see Appendix B). C. Quasiparticle charge and visibilityAs the pairing phenomenon was tied to interference, the charge was measured as a function of the interference visibility, which was suppressed in two ways: (i) redirecting the first-inner edge channel to the inner grounded contact, thereby dephasing the FPI (see next chapter) [14]; and (ii) increasing the transmission of a single QPC of the FPI.Consequently, the interfering charge e * =2e measured at a visibility of ~45%, decreased gradually to e * =e when the visibility was quenched [21]. Yet, as the visibility decreased, the h/2e periodicity remained unchanged. As we argue below, the only way to understand this phenomenon is to assert that single-electron interference is fully dephased in the pairing regime.

Observation of quantum Hall interferometer phase jumps due to a change in the number of bulk quasiparticles

“…In previous experiments, gating potentials and capacitances of similar samples were optimized in such a way [27,30,33,34].…”

Anyons in Quantum Hall Interferometry

“…Owing to this physical picture, great experimental efforts have been made to realize FPIs both in the integer and fractional QH regime [22,[94][95][96][97][98][99][100][101][102][103][104][105][106][107][108][109][110], in order to reveal non-trivial anyonic statistics. Early realizations of FPIs, effectively realizing dots and anti-dots in the fractional quantum Hall phases [111][112][113][114][115], reported oscillations that turned out to be manifestations of fractional charge [116][117][118][119] Indeed, for a small area, of the order of a few µm 2 , strong bulk-edge capacitive coupling characterizes the FPI operation, and a change in the bulk density determines a change of the area enclosed by the edge.…”

Characterization of quasiparticle tunneling in a quantum dot from temperature dependent transport in the integer and fractional quantum Hall regime

“…In previous experiments, cyclic depopulation of two Landau levels in a quantum dot close to filling factor 2 was associated with alternating height of the resonance amplitudes [11]. Other works report magnetic field periods corresponding to half a flux quantum φ 0 /2 around filling factor 5/2 for Fabry-Pérot interferometers [48,49] or capacitance measurements of a QD [52], where this is accompanied by a tunneling quasiparticle charge of 2e, indicating electron pairing [53].…”

“…The back gate was grounded for all measurements presented below, while nevertheless modifying the electron-electron interaction and the electrostatic potential in the sample. The presence of additional gates was used to influence the electrostatic potential in previous experiments [34,35,48,49].…”