Regensburg 2025 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 55: Superconducting Electronics: SQUIDs, Qubits, Circuit QED III

TT 55.9: Vortrag

Freitag, 21. März 2025, 11:45–12:00, H36

Impact of infrared photons on superconducting qubits — •Markus Griedel^1,2, Jonathan Huschle², Hannes Rotzinger^1,2, and Alexey V. Ustinov^1,2 — ¹Institut for Quanten Materials and Technologies (IQMT), Karlsruhe Institut for Technology (KIT), Karlsruhe, Germany — ²hysikalisches Institut (PHI), Karlsruhe Institut for Technology (KIT), Karlsruhe, Germany

Low-noise superconducting quantum circuits are manipulated by microwave photons with energies below the superconducting energy gap. However, the impact of photons with much higher energies may break Cooper pairs and result in an increase in the noise level. Stray infrared (IR) radiation, e.g. transmitted through the dielectrics of coaxial cables, must be blocked by a low-pass filter to avoid this additional noise. The coherence of superconducting qubits is particularly sensitive to this influence and can be used as a detector. In the qBriqs project, we focus on studying the impact of far-infrared photons and present the results of a detailed experimental study. We propose materials to suppress the IR radiation, e.g. with an in-line filter, while maintaining good microwave properties.

Keywords: quantum circuits; superconducting qubits; Josephson junctions; infrared radiation; quasiparticles