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TT: Fachverband Tiefe Temperaturen

TT 7: Focus Session: Disordered and Granular Superconductors: Fundamentals and Applications in Quantum Technology II

TT 7.1: Talk

Tuesday, September 28, 2021, 13:30–14:00, H6

Granular Aluminum: a superconducting material with amenable nonlinearity for quantum circuits — •Ioan Pop — KIT, Karlsruhe, germany

The electrodynamics of granular Aluminum (grAl) can be modeled based on an effective Josephson junction array with high kinetic inductance and amenable nonlinearity[1,2]. This recommends grAl for various applications in quantum technology, including kinetic inductance detectors, parametric amplifiers and quantum bits. One illustration of grAl’s utility in quantum circuit design is the remarkable resilience of grAl fluxonium qubits[3] to photons populating its dispersively coupled readout resonator. This resilience allows single shot QND measurements[4] and quantum state preparation via active feedback with fidelities exceeding 90% even without using a parametric amplifier[5]. An outstanding challenge is the mitigation of non-equilibrium quasiparticles [6].
[1] Maleeva et al. Nature Comm. 9, 3889 (2018)
[2] Winkel et al. Phys. Rev. X 10, 031032 (2020)
[3] Grunhaupt, Spiecker et al. Nature Materials 18, 816-819 (2019)
[4] Takmakov, Winkel, et al. Phys. Rev. App. 15, 064029 (2021)
[5] Gusenkova, Spiecker, et al. Phys. Rev. App. 15, 064030 (2021)
[6] Cardani, Valenti et al. Nat. Commun. 12, 2733 (2021)