Transport through zero-dimensional states in a quantum dot

Abstract

We have studied the electron transport through zero-dimensional (OD) states. OD states are formed when one-dimensional edge channels are confined in a quantum dot. The quantum dot is defined in a two-dimensional electron gas with a split gate technique. To allow electronic transport, connection to the dot is arranged via two quantum point contacts, which have adjustable selective transmission properties for edge channels. The OD states show up as pronounced oscillations in the conductance (up to 40% of e*/h), when the flux enclosed by the confined edge channel is varied, either by changing the magnetic field or the gate voltage. A prerequisite for the appearance of OD states is that the transport through the entire device is adiabatic (i.e. with conservation ofquantum numbers), which will be shown to occur at high magnetic field. The experimental results are in good agreement with theory and show that in the ballistic quantum Hall regime the current is carried entirely by edge channels.

Flux-period scaling in the Laughlin quasiparticle interferometer

“…1(a), the "outer edge ring"] can be determined from the directly-measured Aharonov-Bohm field period B ∆ , using the wellestablished flux quantization condition e h S B / = ∆ = ∆ Φ for the flux period Φ ∆ . 7,8 The Aharonov-Bohm area In S enclosed by the inner 3 / 1 = f edge channel ( Fig. 1(b), the " 5 / 2 = f island area") is necessarily smaller than Out S in the same device.…”

Experimental realization of Laughlin quasiparticle interferometers

“…Complementary device geometry, where an electron island is separated from the 2D system by two nearly open constrictions, is an interferometer. [7][8][9][14][15][16][17][18][19] In this paper we compare results obtained from two interferometer devices. Small differences in device design and fabrication have led to one having more depleted constrictions than another.…”

Low-field quantum Hall transport in an electron Fabry-Perot interferometer: Dependence of constriction filling on front-gate voltage

“…The individual R XY and R XX traces for the same V FG were taken several days apart so that the detailed B-positions and magnitude of the "mesoscopic features" do not match, and thus do not subtract, due to their slow drift as a function of time. AharonovBohm oscillations, [13][14][15][16][17][18] …”

“…Similar electron interferometer devices have been studied by others in the integer QH regime. [17][18][19] Earlier studies of dependence of constriction electron density were done in single unetched quantum point contacts defined by the split-gate technique, where the number of conductance channels was varied between zero ͑pinch-off͒ and a dozen. [11][12][13] Indeed, one reason why no similar work was feasible earlier is that in our devices, the main depletion is provided by etching so that the constriction density can be varied in a wide range while maintaining the device geometry.…”