Parasitic RF-SQUIDs in superconducting qubits due to wirebonds

Fuente: arXiv
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Hauptverfasser: Berlitz, B., Daum, E., Deck, S., Ustinov, A. V., Lisenfeld, J.
Format: Preprint
Veröffentlicht: 2025
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author Berlitz, B.
Daum, E.
Deck, S.
Ustinov, A. V.
Lisenfeld, J.
author_facet Berlitz, B.
Daum, E.
Deck, S.
Ustinov, A. V.
Lisenfeld, J.
contents Superconducting qubits show great promise to realize practical quantum computers from micro-fabricated integrated circuits. However, their solid-state architecture bears the burden of parasitic modes in qubit materials and the control circuitry which cause decoherence and interfere with qubits. Here, we present evidence that wirebonds, which are used to contact the micro-circuits and to realize chip-to-chip airbridges, may contain parasitic Josephson junctions. In our experiment, such a junction was enclosed in a superconducting loop and so gave rise to the formation an RF-SQUID which interfered with a nearby flux-tunable transmon qubit. Periodic signatures observed in magnetic field sweeps revealed a strong AC-dispersive coupling of the parasitic RF-SQUID to both the qubit and its readout resonator, in addition to the DC-inductive coupling between RF-SQUID and qubit. Our finding sheds light on a previously unknown origin of decoherence due to parasitic Josephson junctions in superconducing circuits.
format Preprint
id arxiv_https___arxiv_org_abs_2505_20458
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Parasitic RF-SQUIDs in superconducting qubits due to wirebonds
Berlitz, B.
Daum, E.
Deck, S.
Ustinov, A. V.
Lisenfeld, J.
Superconductivity
Quantum Physics
Superconducting qubits show great promise to realize practical quantum computers from micro-fabricated integrated circuits. However, their solid-state architecture bears the burden of parasitic modes in qubit materials and the control circuitry which cause decoherence and interfere with qubits. Here, we present evidence that wirebonds, which are used to contact the micro-circuits and to realize chip-to-chip airbridges, may contain parasitic Josephson junctions. In our experiment, such a junction was enclosed in a superconducting loop and so gave rise to the formation an RF-SQUID which interfered with a nearby flux-tunable transmon qubit. Periodic signatures observed in magnetic field sweeps revealed a strong AC-dispersive coupling of the parasitic RF-SQUID to both the qubit and its readout resonator, in addition to the DC-inductive coupling between RF-SQUID and qubit. Our finding sheds light on a previously unknown origin of decoherence due to parasitic Josephson junctions in superconducing circuits.
title Parasitic RF-SQUIDs in superconducting qubits due to wirebonds
topic Superconductivity
Quantum Physics
url https://arxiv.org/abs/2505.20458