Dresden 2026 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 22: Superconductivity – Poster I

TT 22.23: Poster

Monday, March 9, 2026, 18:00–20:00, P1

Superconducting Resonators from Ultrathin NbN Films — •Hrishikesh Borah, Meenakshi Sharma, Haolin Jin, Yejin Lee, and Uri Vool — Max Planck Institute for Chemical Physics of Solids

We explore the transport and microwave response of ultrathin Niobium Nitride (NbN) of 3 nm thickness. Transport measurements confirm the 2D behavior of our system, consistent with the Berezinskii-Kosterlitz-Thouless transition. In such ultrathin limit, the inertia of the cooper pairs defined as kinetic inductance becomes dominant. Our films exhibit a high kinetic inductance of 300 pH/sq, which significantly impacts the response of superconducting microwave resonators patterned from the films. Moreover, temperature dependence measurements of the microwave response reveal that in low temperature regime, the superfluid density follows a power-law rather than the BCS prediction. Energy losses at low temperature are dominated by two-level system (TLS) defects while at higher temperatures, losses are caused by the breaking of Cooper pairs. This work investigates the ultrathin NbN regime for compact, high-impedance devices ideal for quantum circuits and sensitive detectors.

Keywords: Microwave resonators; Ultrathin Niobium Nitride (NbN) film; High kinetic inductance; Berezinskii-Kosterlitz-Thouless (BKT) transition; Power Law