(Color online) (a) A photograph and (b) a sectional drawing of the microscope. It connects to the mixing chamber at the top.
(Color online) (a) The sensor: A tuning fork on a small support with a wire glued to one prong. The circuit board diameter is 18 mm. (b) An electron-beam micrograph of a PtIr scanning tip. (c) Topography scan, taken during cooldown 2, showing a quantum dot and an adjacent quantum point contact defined by local anodic oxidation on the surface of a GaAs/AlGaAs heterostructure.
(Color online) Schematic of the PLL (gray box) and the feedback.
(Color online) Measurements and theoretical curves (solid lines) for the PLL transfer function and the transfer function of a sensor with characteristic frequency . (a) and (b): Magnitude and phase of for and (red diamonds), (black crosses), and (blue circles). (c) and (d): for and (red diamonds), (black crosses), and (blue circles). (e) and (f): for , , , , (blue circles), (black crosses), and (red diamonds).
Conductance of a quantum dot as a function of tip position. The tip voltage is (a) ; (b) ; (c) ; and (d) .
The mixing chamber temperature , sample temperature , electron temperature , first cable temperature , and second cable temperature measured in four different cooldowns. All temperatures are in millikelvin (mK) and the accuracy is about .
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