Superconducting quantum detectors

Abstract:

In this paper, we investigate the possibility of utilising a tunnel-junction loaded transmission line as high efficiency parametric frequency multiplier. Through the interaction between the injected primary tone and the nonlinear medium, higher harmonic tones can be generated through wave-mixing process. Here, we aim to maximise the third harmonic wave generation. We first establish a theoretical framework outlining the mechanism for generating the third harmonic component from a single pump wave propagating in a nonlinear transmission line. We begin by demonstrating that strong third harmonic generation is possible with the resonance phase matching technique, albeit with an extremely narrow operational bandwidth. To broaden the bandwidth, we modify the dispersion engineering element of our circuit and show that broadband operation is achievable, while preventing unwanted harmonic tone growth. We extend this calculation from the microwave to the millimetre and sub-millimetre regimes and demonstrate that by adjusting the parameters of the junctions and the dispersion engineering circuits, we can achieve high conversion efficiency close to 1 THz.

Abstract:

Lecture for Graduate Students

Abstract:

Most Josephson junction Travelling Wave Parametric Amplifiers (JTWPAs) developed so far have been focused on operation below 20 GHz, primarily driven by the choice of the qubit resonance frequency used in quantum computation research. Consequently, there is a lack of effort to extend their operation to higher frequency ranges. However, millimetre (mm)- wave JTWPAs could offer potential significant advantages for astronomy, but their operation in this regime is largely unexplored. In this paper, we describe the design considerations for extending JTWPAs operation to the W-band range. We present two JTWPA designs, one with and one without phase matching elements, and we discuss the design methodology of both approaches, before showing their predicted performance respectively.