SKM 2023 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 58: Poster: Superconductivity II

TT 58.3: Poster

Donnerstag, 30. März 2023, 15:00–18:00, P2/OG3

Integrated two-stage SQUID-chip with 6 nH input impedance — •David Mazibrada, Fabian Krämer, Alexander Stoll, Nicolas Kahne, Lukas Münch, Daniel Hengstler, Andreas Fleischmann, and Christian Enss — Kirchhoff-Institute for Physics, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany.

SQUIDs are sensitive superconducting magnetic flux to voltage converters, whose operation is based on the Josephson effects. To increase the signal-to-noise ratio of a SQUID-based readout system one can amplify the signal with an N-SQUID series array. We present our first integrated two-stage chip design which combines a single current sensing dc-SQUID as front-end and a 18-dcSQUID series array as amplifier stage, in one compact, well thermalized chip. This not only eliminates the need for two separate chips, but also achieves low signal propagation delay and larger bandwidth. Compared to our most recent single-stage current sensing SQUIDs, the first stage SQUID features a 2-turn input coil with increased inductance of 6 nH increasing the input current sensitivity by a factor of about 2. To counteract the resistive heating of the two-stage setup, large thermalization pads made of gold are implemented to thermalize the resistive elements and in addition the chip can be thermally anchored to the sample holder by means of gold bonds. In future designs lossy striplines will be used in order to provide delocalized broad-band damping and suppress effects of parasitic resonances without introducing new noticeable sources of noise.