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 quasiparticle bursts [6] and two level systems in its environment [7].
[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)
[7] Spiecker et al. in preparation