Dresden 2020 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 16: Poster Session Superconductivity, Cryogenic Particle Detectors, Cryotechnique

TT 16.30: Poster

Monday, March 16, 2020, 15:00–19:00, P2/EG

dc-SQUID readout with intrinsic frequency-division multiplexing capability and high dynamic range — •Ludwig Hoibl, Daniel Richter, Andreas Fleischmann, Christian Enss, and Sebastian Kempf — Kirchhoff-Institute for Physics, Heidelberg University, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany

Direct-current superconducting quantum interference devices (dc-SQUIDs) are extraordinarily sensitive flux-to-voltage converters. Due to their periodic flux-to-voltage characteristic, the linear flux range is rather small. For this reason, a flux locked loop (FLL) circuit is typically used to linearize the output signal. However, FLL operation often sets a practical limit for the realization of multi-channel SQUID systems since feedback wires have to be routed to each SQUID. There is hence a great need for SQUID based multi-channel readout techniques, providing a linear input-output signal relation.
In this contribution, we present a frequency-division multiplexing (FDM) readout technique with linear input-output signal relation and simultaneously a large dynamic range. It is based on flux-ramp modulation and hence relies on converting the input signal into a phase shift of the flux-to-voltage SQUID characteristic which is continuously measured by applying a periodic, sawtooth-shaped flux signal to the SQUID. We introduce the basic concept of our multiplexing technique and discuss the performance of a home-made four channel multiplexer device. Moreover, we present the status and performance of a custom-made readout electronics as well as potential applications in detector readout.