Superconducting fluxonium qubits provide a promising alternative to transmons on the path toward large-scale superconductor-based quantum computing due to their better coherence and larger anharmonicity. A major challenge for multi-qubit fluxonium devices is the experimental demonstration of a scalable crosstalk-free multi-qubit architecture with high-fidelity single-qubit and two-qubit gates, single-shot readout, and state initialization. Here, we present a two-qubit fluxonium-based quantum processor with a tunable coupler element. We experimentally demonstrate fSim-type and controlled-Z-gates with 99.55 and 99.23% fidelities, respectively. The residual ZZ interaction is suppressed down to the few kHz levels. Using a galvanically coupled flux control line, we implement high-fidelity single-qubit gates and ground state initialization with a single arbitrary waveform generator channel per qubit.

A novel material platform based on metallic thin films with ultra-low losses in the visible and near-IR range is crucial for rapid development of a wide range of new generation plasmonic devices. For many years silver has been known as potentially the best plasmonic material with the naturally lowest ohmic losses at optical frequencies. However, the widespread implementation of the silver-based material platform for plasmonics and metamaterials is limited due to technological challenges in thin film synthesis and nanoscale features fabrication techniques. This review describes the main types of silver-based plasmonic devices from the thin films point of view required for their widespread practical application. Based on comparative analysis of more than 60-year-long history of previously reported data for the silver thin films, the authors formulate the qualitative and quantitative criteria of "ideal" silver film (which the authors name the silver "dream" plasmonic film) for plasmonic devices with ultra-low loss. This paper outlines on several well-known metrology issues in plasmonic metallic films characterization and summarize the set of methods for their properties careful and precise extraction. Finally, the detailed analysis of silver synthesis techniques and quantitative comparison of the achieved silver properties is carried out.

We demonstrate nonequilibrium steady-state photon transport through a chain of five coupled artificial atoms simulating the driven-dissipative Bose-Hubbard model. Using transmission spectroscopy, we show that the system retains many-particle coherence despite being coupled strongly to two open spaces. We find that cross-Kerr interaction between system states allows high-contrast spectroscopic visualization of the emergent energy bands. For vanishing disorder, we observe the transition of the system from the linear to nonlinear regime of photon blockade in excellent agreement with the input-output theory. Finally, we show how controllable disorder introduced to the system suppresses nonlocal photon transmission. We argue that proposed architecture may be applied to analog simulation of many-body Floquet dynamics with even larger arrays of artificial atoms paving an alternative way towards quantum supremacy.