Low-Frequency Microwave Response of a Quantum Point Contact

The low-frequency microwave photoconductance of a short (100 nm) quantum point contact based on a high-mobility two-dimensional electron gas in the frequency range of 2–3 GHz is investigated for the first time. The giant photoconductance in the tunneling regime and the negative photoconductance in the open regime are observed. It is shown by numerical simulations that such response to microwave irradiation is caused by the forced oscillations of the saddle-point potential in the quantum point contact and of the probe voltage applied to the contact.