Abstract
The origin and the evolution of the universe are concealed in the evanescent diffuse extragalactic background radiation (DEBRA). To reveal these signals, the development of innovative ultra-sensitive bolometers operating in the gigahertz band is required. Here, we review the design and experimental realization of two bias-current-tunable sensors based on one dimensional fully superconducting Josephson junctions: the nanoscale transition edge sensor (nano-TES) and the Josephson escape sensor (JES). In particular, we cover the theoretical basis of the sensors operation, the device fabrication, their experimental electronic and thermal characterization and the deduced detection performance. Indeed, the nano-TES promises a state-of-the-art noise equivalent power (NEP) of about 5×10−20 W/Hz, while the JES active region is expected to show an unprecedented NEP of the order of 10−25 W/Hz. Therefore, the nano-TES and JES are strong candidates to push radio astronomy to the next level.
Highlights
The universe is permeated by radiation extending over almost all the electromagnetic spectrum, the so-called diffuse extragalactic background radiation (DEBRA) [1]
These two temperatures define two distinct operating conditions for the 1D fully superconducting Josephson junction (1D-JJ): the nano-transition edge sensors (TESs) operates at TC, i.e., at the middle of the superconductor-to-normal-state transition, and the Josephson escape sensor (JES) operates at Te, i.e., deeply in the superconducting state
In JES-mode, the device has to be biased at Te ( I ), i.e., at R = 0, and the role of RS is to limit the current flow through the sensing element below the retrapping current (IR ) [46], that is the switching current at which a diffusive superconducting wire switches into the dissipationless state from the normal-state during a current down-sweep
Summary
The universe is permeated by radiation extending over almost all the electromagnetic spectrum, the so-called diffuse extragalactic background radiation (DEBRA) [1]. To push detection technology towards lower values of NEP, it is necessary a strong reduction of the thermal exchange of the sensor active region, i.e., the portion of the device absorbing the incident radiation, with all the other thermal sinks. We review recent developments of superconducting radiation sensors based on a structure that shares many technological aspects with the already employed TESs and KIDs. the nanoscale transition edge sensor (nano-TES) [33] and the Josephson escape sensor (JES) [34]. Are envisioned by downsizing the active region of a TES to the nano-scale They employ a one dimensional fully superconducting Josephson junction (1D-JJ) as radiation absorber.
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