Quasiparticle heterodyne mixing in SIS tunnel junctions

Abstract

The rapid onset of quasiparitcle tunneling current in superconductor-insulator-superconductor (Josephson) junctions at voltages above 2Δ/e is being used for millimeter-wave heterodyne mixing. Junctions with a 2-μm diameter and RN=50 Ω have little capacitive shunting at the signal frequency of 36 GHz. Because there is no series resistance, residual capacitance can be tuned out. Double sideband conversion efficiencies of 0.32 and mixer noise temperatures as low as TM⩽7 K=4hν/k have been observed. The results are compared with shot-noise-limited mixer theory. Photon-assisted tunneling effects are seen which indicate the approach to photon-noise-limited operation.

Terahertz detectors and focal plane arrays

“…First proposition of pair−breaking detector The SIS operation is based on photoassisted tunnelling of quasi−particles through the insulating layer. Although the physics of this effect was demonstrated and theoretically explained already in the 1960s [161,162], it took almost two decades to make use of the effect in a mixer [163,164]. Nowadays, SIS tunnel junctions are mainly used as mixers in heterodyne type mm and sub−mm receivers because of their strong non−linear I−V characteristic.…”

Superconducting detectors and mixers for millimeter and submillimeter astrophysics

“…The physics of this effect was demonstrated experimentally in the early 1960s by Dayem and Martin [165], and explained theoretically by Tien and Gordon [166]. The first demonstrations of SIS mixing were published [167], [168] in 1979, after the technology for making suitably small-area SIS junctions had been developed. Phillips and Woody [43] provided an interesting summary of early SIS work.…”

Submillimeter-wave detection with superconducting tunnel diodes

“…Twelve years ago, the first descriptions of mixing on a superconducting tunnel diode called a Superconductor-Insulator-Superconductor (SIS) were published [1,2]. At about the same time, a comprehensive theoretical investigation of the SIS made clear that SIS's respond to photons at millimeter and submillimeter wavelengths [3].…”