Quantum transport in electron Fabry-Perot interferometers

Abstract

We report experiments on Fabry-Perot electron interferometers in the integer quantum Hall regime. The GaAs/AlGaAs heterostructure devices consist of two constrictions defined by etch trenches in 2D electron layer, enclosing an approximately circular island. The interferometer is formed by counterpropagating chiral edge channels coupled by tunneling in the two constrictions. Interference fringes are observed as conductance oscillations, similar to the Aharonov-Bohm effect. Front gates deposited in etch trenches allow to fine-tune the device and to change the constriction filling f relative to the bulk filling. Quantum-coherent conductance oscillations are observed on the f = 1 - 4 plateaus. On plateau f we observe f conductance oscillations per fundamental flux period h/e. This is attributed to the dominance of the electron-electron Coulomb interaction, effectively mixing Landau level occupation. On the other hand, the back-gate charge period is the same (one electron) on all plateaus, independent of filling. This is attributed to the self-consistent electrostatics in the large electron island. We also report dependence of the oscillation period on front-gate voltage for f = 1, 2 and 4 for three devices. We find a linear dependence, with the slope inversely proportional to f for f = 1 and 2

Interplay of fractional quantum Hall states and localization in quantum point contacts

“…In contrast, scanning SET experiments provided information about individual localizations, but not about their influence on transport. For the interpretation of interference experiments in the quantum Hall regime [46][47][48][49][50] , a detailed understanding of the transmission properties of single QPCs is necessary. Even in 2DEGs with the highest mobilities technologically achievable at the moment, disorder significantly influences transport through the QPC, as soon as a perpendicular magnetic field is applied.…”

Quantum Hall Mach-Zehnder interferometer at fractional filling factors

“…(ii) By contrast, low-size Fabry-Perot interferometers clearly demonstrate interference oscillations even in the fractional regime [10][11][12][13][14][15][16]. On the other hand, the interference pattern was shown [15,16] to be determined by Coulomb blockade effects [17] at fractional fillings.…”

Quantum Hall Mach-Zehnder interferometer far beyond equilibrium

“…Recent investigations of quantum Hall (QH) interferometers [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] give rise to several fundamental puzzles even in the integer QH regime. The major ones are the influence of the electron-electron interaction on the interference pattern 10,15,17 and the nature of the decoherence 2,7,16 .…”