New devices based on an HTS intrinsic Josephson junction

Wakana Hironori, Seiji Adachi, Tsunehiro Hato +3 more

Dan Qiao, Xiang Gao, Ziru Chen +4 more

This paper presents the design and simulation of a 220-GHz miniaturized slot-antenna-coupled high-temperature superconducting (HTS) mixer, which integrates the HTS junction and the choke filter on one single substrate. The presented mixer utilizes$\mathbf{Bi_{2}}\mathbf{Sr_{2}}\mathbf{CaCu}2\mathbf{O_{8}}$(BSCCO) intrinsic Josephson junction array as the nonlinear mixing device. To compensate the parasitic capacitance of the BSCCO junction, a short transmission line is used as an inductance for improving impedance matching between the slot antenna and the BSCCO Josephson junction array. The simulation results show that the proposed mixer achieves a conversion gain and noise temperature of -6.74 dB and 266.28 K @ 50K, respectively.

Jens Scherbel

Josephson junctions made from high temperature superconductors (HTS) are active high frequency devices which can be used as oscillators or frequency mixers in the submillimeter-wave region. The frequencies of these electromagnetic waves range from 300 GHz up to 3 THz. Up to now, this wave band is a relatively unexploited region of the electromagnetic spectrum because it is very difficult to produce and detect submillimeter-waves. However, submillimeter-wave technologies are becoming important in many practical scientific applications such as radio astronomy, atmospheric research, plasma diagnostics and THz-imaging, recently. In this work, the behaviour HTS Josephson junctions have been investigated experimentally and theoretically with the aim to THz-applications. In the first part the behaviour of intrinsic Josephson junction stacks are measured, and the possibility of phase locking is discussed by the theoretical analysis of two different shunt technologies depending on the parameter spread of the junction and the shunt parameters. It could be shown that stacks made from sputtered BSCCO layers does not act as intrinsic Josephson junction arrays because of their many micro shorts resulting from the layer growth. However, the stacks made from sputtered TBCCO show clear intrinsic Josephson junction behaviour. But their quasiparticle branches in the current-voltage characteristic deviate from the behaviour predicted by the common used RCSJ model. These branches can be discussed within a tunneling model using d-wave superconductor density of states. A temperature dependent current distribution and a zero bias anomaly was found. Furthermore, the coherent behaviour is studied for intrinsic arrays with additional side-wall shunts. The existence of thresholds of phase locking at especial junction and shunt parameters are demonstrated and discussed in regard to THz-oscillator applications. It was found that the Josephson junctions in a stack can be phase locked even if they have a parameter spread in the critical current up to 15% using a resonant shunt. In the second part of this work the mixing properties of HTS bicrystal Josephson junctions as wave guide mixers for 115 and 345 GHz have been investigated. (orig.)

S. Pagano, Sandro Barbanera, Vincenzo Boffa +6 more

Jia Du

The CSIRO Applied Superconductivity Group has a long-term effort in research and development of superconducting electronic devices and systems for various practical applications. In this talk, I will give an overview of CSIRO research activities in developing high-Tcsuperconducting (HTS) Josephson junction devices for various applications. I will firstly describe the CSIRO-developed HTS step-edge Josephson junction technology and its basic application in Superconducting Quantum Interference Devices (SQUIDs). I will then describe in more detail our recent research progress on developing high-Tcsuperconducting (HTS) Josephson devices for microwave and terahertz (THz) applications.

Giovanni Costabile, S. Pagano, Niels Falsig Pedersen +1 more