Frequency conversion of radio-frequency edge magnetoplasmons using a quantum point contact.

We report a frequency-conversion technique for edge magnetoplasmons in a quantum Hall device. The nonlinear conductance of a quantum point contact (QPC) results in the generation of high harmonics of an input microwave and the mixing of two input frequencies. We controlled the conversion efficiency by tuning the nonlinear conductance via a gate voltage. The amplitudes of the frequency-converted waves agree well with those expected from the measured dc nonlinear conductance. We demonstrate the technique up to our instrumental limit of 12 GHz and show that formation of charge-density waves does not change the nonlinear characteristics of the QPC. [ABSTRACT FROM AUTHOR]