Evidence for correlated electron pairs and triplets in quantum Hall interferometers.

The pairing of electrons is ubiquitous in electronic systems featuring attractive inter-electron interactions, as exemplified in superconductors. Counterintuitively, it can also be mediated in certain circumstances by the repulsive Coulomb interaction alone. Quantum Hall (QH) Fabry-Pérot interferometers (FPIs) tailored in a two-dimensional electron gas under a perpendicular magnetic field have been argued to exhibit such an unusual electron pairing, seemingly without attractive interactions.

Appearance of fractional charge in the noise of nonchiral Luttinger liquids.

The current noise of a voltage biased interacting quantum wire adiabatically connected to metallic leads is computed in the presence of an impurity in the wire. We find that in the weak backscattering limit the Fano factor characterizing the ratio between noise and backscattered current crucially depends on the noise frequency omega relative to the ballistic frequency vF/gL, where vF is the Fermi velocity, g is the Luttinger liquid interaction parameter, and L is the length of the wire. In contrast to chiral Luttinger liquids the noise is not only due to the Poissonian backscattering of fractionally charged quasiparticles at the impurity, but it also depends on Andreev-type reflections at the contacts, so that the frequency dependence of the noise needs to be analyzed to extract the fractional charge e*=eg of the bulk excitations.

Oscillatory nonlinear conductance of an interacting quantum wire with an impurity.

The nonlinear conductance of a one-dimensional quantum wire adiabatically coupled to Fermi liquid electron reservoirs is determined in the presence of an impurity. We show that electron-electron interaction in connection with the finite length of the wire leads to characteristic oscillations in the current as a function of the applied voltage.