A millimeter wave Josephson mixer employing a high-<i>T</i> <i>c</i> GdBaCuO point contact

Abstract

We have investigated a Josephson effect heterodyne mixer for the millimeter wave band employing high-Tc GdBaCuO point contacts. Mixer performance was in qualitative agreement with theory. A mixing response was observed up to 55 K, the highest operating temperature achieved for such a device to date. The voltage separation of rf-induced steps gave a value of h/2e=2.08×10−15 V s which is in excellent agreement with the value expected for Cooper pairs. In addition, the temperature dependence of the I0R product was found to agree with Bardeen–Cooper–Schrieffer theory in the weak coupling limit.