Quantum theory is expected to govern the electromagnetic properties of a quantum metamaterial, an artificially fabricated medium composed of many quantum objects acting as artificial atoms. ...Propagation of electromagnetic waves through such a medium is accompanied by excitations of intrinsic quantum transitions within individual meta-atoms and modes corresponding to the interactions between them. Here we demonstrate an experiment in which an array of double-loop type superconducting flux qubits is embedded into a microwave transmission line. We observe that in a broad frequency range the transmission coefficient through the metamaterial periodically depends on externally applied magnetic field. Field-controlled switching of the ground state of the meta-atoms induces a large suppression of the transmission. Moreover, the excitation of meta-atoms in the array leads to a large resonant enhancement of the transmission. We anticipate possible applications of the observed frequency-tunable transparency in superconducting quantum networks.
The spectral and temporal characteristics of a fluxonium qubit coupled to a coplanar resonator on a chip have been experimentally studied. The system has been implemented as a planar integral ...electric circuit, where the fluxonium qubit itself consists of a tunnel Josephson junction with a small area shunted by a high inductance of a series of Josephson junctions with larger areas. To analyze the experimental data, an extended model of the fluxonium qubit capacitively coupled to the resonator has been proposed, and the structure of the energy levels has been obtained by full diagonalization of the Hamiltonian of the system. Numerical predictions of the model allow interpreting the results of two-tone spectroscopy obtained at various external magnetic fluxes in a wide frequency range.
We report a detailed theoretical study of a coherent macroscopic quantum-mechanical phenomenon-quantum beats of a single magnetic fluxon trapped in a two-cell SQUID of high kinetic inductance. We ...calculate numerically and analytically the low-lying energy levels of the fluxon and explore their dependence on externally applied magnetic fields. The quantum dynamics of the fluxon shows quantum beats originating from its coherent quantum tunneling between the SQUID cells. We analyze the experimental setup based on a three-cell SQUID, allowing for time-resolved measurements of quantum beats of the fluxon.
Recently, in Ukraine a trend to increased incidence of suppurative osteomyelitis of the spine is defined. The main factors contributing to incidence increase is the growth of proportion of population ...with immunodeficiency and implementation of computer and magnetic resonancetomography in clinical practice. Treatment of suppurative osteomyelitis of the spine should include antibiotic therapy, adequate sanitation of the infectious focus, strict bed rest with exercise therapy. Tactics of surgical treatment combined with antibiotic deescalation therapy with glycopeptide antibiotic - teicoplanin and rehabilitation program which helped to achieve recovery in 23 (37.8%) of patients treated conservatively and in 55 (91%) of the operated patients was proposed.
Oblique X-ray diffraction images of individual dislocations in the symmetric Laue geometry from a plane-parallel silicon plate have been calculated based on the Takagi-Taupin equations and analyzed. ...Computer simulation is used to develop a general mathematical model of the formation of oblique images which correspond to sample rotation around the diffraction vector
h
in X-ray topo-tomography. The results of numerical calculations and analysis of different oblique images of straight-line dislocations, where the dislocation line vector
τ
lies in a plane parallel to input surface of {111}Si plate with a diffraction vector
h
〈220〉, are presented.
Experimental realization of stabilizer-based quantum error correction (QEC) codes that would yield superior logical qubit performance is one of the formidable task for state-of-the-art quantum ...processors. A major obstacle towards realizing this goal is the large footprint of QEC codes, even those with a small distance. We propose a circuit based on the minimal distance-3 QEC code, which requires only 5 data qubits and 5 ancilla qubits, connected in a ring with iSWAP gates implemented between neighboring qubits. Using a density-matrix simulation, we show that, thanks to its smaller footprint, the proposed code has a lower logical error rate than Surface-17 for similar physical error rates. We also estimate the performance of a neural network-based error decoder, which can be trained to accommodate the error statistics of a specific quantum processor by training on experimental data.
The superconducting fluxonium circuit is an RF-SQUID-type flux qubit that uses a large inductance built from an array of Josephson junctions or a high kinetic inductance material. This inductance ...suppresses charge sensitivity exponentially and flux sensitivity quadratically. In contrast to the transmon qubit, the anharmonicity of fluxonium can be large and positive, allowing for better separation between the low energy qubit manifold of the circuit and higher-lying excited states. Here, we propose a tunable coupling scheme for implementing two-qubit gates on fixed-frequency fluxonium qubits, biased at half flux quantum. In this system, both qubits and coupler are coupled capacitively and implemented as fluxonium circuits with an additional harmonic mode. We investigate the performance of the scheme by simulating a universal two-qubit fSim gate. In the proposed approach, we rely on a planar on-chip architecture for the whole device. Our design is compatible with existing hardware for transmon-based devices, with the additional advantage of lower qubit frequency facilitating high-precision gating.
We report a detailed theoretical study of a coherent macroscopic quantum-mechanical phenomenon - quantum beats of a single magnetic fluxon trapped in a two-cell SQUID of high kinetic inductance. We ...calculate numerically and analytically the low-lying energy levels of the fluxon, and explore their dependence on externally applied magnetic fields. The quantum dynamics of the fluxon shows quantum beats originating from its coherent quantum tunneling between the SQUID cells. We analyze the experimental setup based on a three-cell SQUID, allowing for time-resolved measurements of quantum beats of the fluxon.
PDF
