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MON: Monday Contributed Sessions

MON 14: QIP Implementations: Solid-State Devices I

MON 14.6: Vortrag

Montag, 8. September 2025, 17:45–18:00, ZHG002

Josephson Qubits with a DC Voltage Drive — •Florian Höhe¹, Ciprian Padurariu¹, Björn Kubala^{1, 2}, and Joachim Ankerhold¹ — ¹ICQ and IQST, Ulm University, Ulm, Germany — ²Institute of Quantum Technologies, German Aerospace Center (DLR), Ulm, Germany

Superconducting qubits utilize a Josephson junction as a nonlinear element to create a non-linear oscillator with unequally spaced energy levels. Coherent AC pulses, resonant with the transition frequency between the two lowest energy eigenstates, |0⟩ and |1⟩, enable quantum gate operations while leaving higher energy states largely unaffected.
In Josephson-photonics devices, a DC-biased Josephson junction generates excitations within a microwave LC resonator. Although the resonator’s energy levels are equally spaced, the intrinsic nonlinearity of the drive can be exploited to suppress the |1⟩ → |2⟩ transition. This effectively turns the system into a two-level qubit that can be controlled by tuning the Josephson energy through a SQUID, eliminating the need for AC pulses.
In this work, we propose a method for implementing both single- and multi-qubit gates for qubits based on DC-biased Josephson junctions. The typically large Josephson energy in these devices may allow for fast and efficient gate operations.

Keywords: Josephson photonics; Superconducting qubits; Nonlinear dynamics; Quantum microwaves