Regensburg 2025 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 50: Superconducting Electronics: SQUIDs, Qubits, Circuit QED II
TT 50.1: Vortrag
Donnerstag, 20. März 2025, 15:00–15:15, H36
Development of ultrasensitive dc SQUIDs with sub-micrometric circuit elements — •Mauro Esattore1, Michael Paulsen2, Jörn Beyer2, Oliver Kieler1, Mark Bieler1, Patryk Krzysteczko2, and Rainer Körber2 — 1Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany — 2Physikalisch-Technische Bundesanstalt, Abbestraße 2-10, 10587 Berlin, Germany
The dc SQUID is one of the most established applications of superconductor technology. Their sensitivity to magnetic flux allows for numerous applications, such as low-temperature thermometry or current sensing for electrical metrology. In this contribution, we present superconducting "fine-pitch" input coils with sub-micrometric parameters to be integrated into existing Nb/Al-AlOx/Nb-based SQUID sensor designs. The aim is to reduce inductive losses of the signal-to-SQUID coupling, without compromising the overall device layout. In a SQUID current sensor, to maximize the inductive coupling constant k between the signal input coil and the SQUID loop means to achieve a low coupled energy sensitivity єc = (1/k2)×є - where є is the SQUID-intrinsic energy sensitivity. Fine-pitch input coils will increase k, as well as extend the range of input coil inductances for our existing devices. The energy sensitivity є ∝ √C: reduced Josephson junction (JJ) sizes will lower the capacitance C and improve єc. Thus, we are refining our JJ definition process to obtain JJs with sub-micrometric lateral size. The contribution will provide details on the fabrication process and design aspect of the sensors, as well as characterization results.
Keywords: Superconductivity; SQUIDs; Sub-micrometer; Fabrication; Low temperature