Figure 3
From: Demonstration of electron focusing using electronic lenses in low-dimensional system
Focusing peak as a function of asymmetric gate bias after illumination. (a) Conductance characteristic of QPC1 with different asymmetric gate bias ΔV; gate voltage Vsg was applied to the bottom arm of the split gate [refers to Fig. 1(b)], Vsg + ΔV was applied to the upper arm. Series resistance has not been removed. The red arrow highlights the occurrence of a sub-0.7-anomaly. (b) Focusing peak with different ΔV applied to QPC1. QPC1 was set to G0, the gate voltage applied to the two arms of QPC1 were calibrated according to (a), QPC2 was not used; QPC3 was under symmetric gate bias and fixed at G0. Data in (b) have been offset vertically for clarity. (c) Peak position (blue) and FWHM (red) as a function of ΔV. It is necessary to mention a background has been removed in determining the FWHM. The background can be determined from two ways: 1. make a polynomial fitting in the vicinity of the focusing peak, as shown in Supplemental Fig. 4; 2. scales the data with both Ohmic 4 and 5 floating which does not include the correction due to focusing process, so that at zero lens gate voltage (the scaled) I3 is the same when Ohmic 4 and 5 are floating and grounded. The two methods lead to a similar conclusion.
