Edge-channel interference controlled by Landau level filling

Abstract

We study the visibility of Aharonov-Bohm interference in an electronic Mach-Zehnder interferometer in the integer quantum Hall regime. The visibility is controlled by the filling factor and is observed only between Ϸ 2.0 and 1.0, with an unexpected maximum near = 1.5. Three energy scales extracted from the temperature and voltage dependences of the visibility change in a very similar way with the filling factor, indicating that the different aspects of the interference depend sensitively on the local structure of the compressible and incompressible strips forming the quantum Hall edge channels.

Suppression of Interference in Quantum Hall Mach-Zehnder Geometry by Upstream Neutral Modes

“…From a broader perspective, here we explore how these two experimental facts, namely the undetectability of anyonic AB fringes in MZI (unlike the high visibility of interference in the integer QH regime [8][9][10][11][12][13][14]), and the ubiquity of upstream neutral modes in FQH systems, are related. We show that the latter leads to an exponential suppression of the former.…”

“…A natural probe of statistics is through its effect on the AharonovBohm (AB) interferometry of anyons moving along the gapless edges of a FQH system. Mach-Zehnder interferometers [8][9][10][11][12][13][14] would have been efficient tools to observe anionic interferometry as they avoid interference-masking Coulomb effects [15,16] and are robust against further quasiparticle fluctuations in the bulk [17][18][19].The interfering paths of a Mach-Zehnder interferometer (MZI) rely on the chiral edge modes of the FQH geometries. Multimode edges [20][21][22] present one with an interesting twist: the possibility of upstream moving modes (i.e., modes moving against the "downstream" direction set by the magnetic field).…”

Probing Cooper pairs with Franson interferometry

“…The quasi-one-dimensionality of the edge current is also appropriate for constructing interferometers, and MZIs were actually realized [21][22][23][24] and correlation experiments were also performed 27,28 in such systems. Furthermore the possibility of interfacing quantum Hall bars with superconductors at high magnetic fields has been recently established in Refs.…”

“…The phases ϕ L/R can be induced by the Aharonov-Bohm effect, by applying magnetic field perpendicular to the MZIs. [21][22][23][24][28][29][30][31] It is clear that the formulas for the optical case are translated to those for the electric case by simply substituting k 0 → k F and c → v F , and the pair wave function Φ(x) of the emitted Cooper pair is given by (49). The single-electron detection rate at (L/R, −), on the other hand, is proportional to…”

“…[18][19][20] Interferometric setups required for such proposed experiments for electrons in solids have already been realized (e.g., see Refs. [21][22][23][24], and several correlation experiments have been carried out, [25][26][27][28][29][30][31] also with superconducting sources of electrons.…”