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TT: Fachverband Tiefe Temperaturen
TT 41: Superconducting Qubits (joint session QI/TT)
TT 41.5: Vortrag
Mittwoch, 20. März 2024, 10:30–10:45, HFT-FT 131
Magnetic field dependence of a Josephson travelling wave parametric amplifier — •Lucas Janssen1, Christian Dickel1, Guilliam Butseraen2, Jonas Krause1, Alexis Coissard3, Luca Planat3, Gianluigi Catelani4, Nicolas Roch2, and Yoichi Ando1 — 1University of Cologne, Cologne, Germany — 2Institut Néel, Grenoble, France — 3Silent Waves, Grenoble, France — 4Technology Innovation Institute, Abu Dhabi, United Arab Emirates
We investigate the magnetic field dependence of a Josephson travelling-wave parametric amplifier (TWPA) that is designed as a version of photonic crystal. We show that the change in photonic bandgap and plasma frequency of the TWPA can be modelled by considering the suppression of the critical current in the Josephson junctions (JJs) of the TWPA due to the Fraunhofer effect and closing of the superconducting gap in magnetic fields. These dependencies allow us to tune the operation of the TWPA by magnetic fields in a wide range of frequencies without using SQUIDs. The JJ geometry is found to be crucial for the magnetic-field dependences: for example, the TWPA bandgap can be widely shifted without losing gain or bandwidth by an in-plane magnetic field in one direction, while in the other in-plane direction the TWPA performance is severely compromised already at 2mT. With out-of-plane field, the TWPA's response is hysteretic, and it is severely compromised at 5mT. We also show that we can use magnetic shielding to use the TWPA in experiments where high fields are required.
Keywords: Parametric amplification; TWPA; Magnetic field compatibility; Qubit readout