Superconducting quantum detectors

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Lecture for Graduate Students

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The Heterodyne Spectrometer Instrument (HSI) is a heterodyne array receiver designed for the Far-IR Spectroscopy Space Telescope (FIRSST), a proposal recently submitted to NASA’s APEX call. FIRSST aims to study the processes of planet formation, to explore how water travels from the interstellar medium to rocky planets and to investigates the growth of black holes and galaxies. FIRSST has two instruments. HSI is designed to study the trail of water and is able to observe the important low-lying transitions of water and its isotopes between 500 and 2000 GHz undetectable from the ground due to Earth’s atmosphere. HSI has a spectral resolving power of up to 107 (0.03kms-1 ), ideal for kinematic studies or line tomography. HSI has six 5-pixel-arrays covering 3 frequency bands and 2 linear polarizations, and is the first focal plane array receiver on a space mission. The concept study showed that a heterodyne array receiver can be build today with high Technology Readiness Level (TRL) components (≥6). HSI is a powerful and versatile instrument, with low-risk technology opening up the THz sky for new discoveries.

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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.