A tunable rf SQUID manipulated as flux and phase qubit

We report on two different manipulation procedures of a tunable rf SQUID. First, we operate this system as a flux qubit, where the coherent evolution between the two flux states is induced by a rapid change of the energy potential, turning it from a double well into a single well. The measured coherent Larmor-like oscillation of the retrapping probability in one of the wells has a frequency ranging from 6 to 20 GHz, with a theoretically expected upper limit of 40 GHz. Furthermore, here we also report a manipulation of the same device as a phase qubit. In the phase regime, the manipulation of the energy states is realized by applying a resonant microwave drive. In spite of the conceptual difference between these two manipulation procedures, the measured decay times of Larmor oscillation and microwave-driven Rabi oscillation are rather similar. Due to the higher frequency of the Larmor oscillations, the microwave-free qubit manipulation allows for much faster coherent operations.Comment: Proceedings of Nobel Symposium "Qubits for future quantum computers", Goeteborg, Sweden, May 25-28, 2009; to appear in Physica Script

High resolution measurements of the switching current in a Josephson tunnel junction: Thermal activation and macroscopic quantum tunneling

We have developed a scheme for a high resolution measurement of the switching current distribution of a current biased Josephson tunnel junction using a timing technique. The measurement setup is implemented such that the digital control and read-out electronics are optically decoupled from the analog bias electronics attached to the sample. We have successfully used this technique to measure the thermal activation and the macroscopic quantum tunneling of the phase in a small Josephson tunnel junction with a high experimental resolution. This technique may be employed to characterize current-biased Josephson tunnel junctions for applications in quantum information processing.Comment: 10 pages, 8 figures, 1 tabl

Complexation of 1-hexadecyl-4-aza-1-azoniabicyclo[2.2.2]octane bromide with nickel nitrate in acetone

© 2016, Pleiades Publishing, Ltd.The complexation of 1-hexadecyl-4-aza-1-azoniabicyclo[2.2.2]octane bromide with Ni(II) nitrate in acetone is studied by means of spectrophotometry (the Job–Ostromisslensky technique and molar ratios). The formation of 3: 1 and 1: 1 ligand: metal complexes is established and confirmed by mathematical modeling. The stability constants of the complexes and the change in the Gibbs free energy are determined

The Modern World Landscape of Data Science Online Education

Data science as an emerging branch of applied knowledge and a new field of study is showing a strong momentum. Besides, the corresponding sphere of educational research is actively developing. At the same time, most of the scientific publications are aimed at studying specific issues related to the content of the programs and their methodological support. The wider context and especially the international perspective are lacking for the necessary attention of researchers.In this regard, the purpose of our study was to summarize and systematize information about training programs in the field of data science presented on online platforms of the main macro-regions – America, Europe and Asia. For this purpose, we found out what elements the corpus of data science training programs consists of, as well as how courses are distributed on educational platforms by countries, organizational providers, level of education and duration of study. Based on the data obtained, we conducted a comparative interregional study of educational programs presented on online platforms.The findings made it possible to draw conclusions about the specifics of the global landscape of data science online education, as well as to determine the specifics of the Russian segment and to formulate recommendations for solving significant problems of the domestic economy using data science online education

Complexes of 1-alkyl-4-aza-1-azoniabicyclo[2.2.2]octane bromides with lanthanum nitrate. Micelle-forming and adsorption properties

© 2017, Pleiades Publishing, Ltd. Novel organometallic surfactants were synthesized from monoquaternized 1,4-diazabicyclo[2.2.2]-octanes of varied hydrophobicity [Alk = C n H 2n+1 , n = 14, 18] and lanthanum nitrates. The spectral, micelleforming, and adsorption properties of the synthesized compounds were studied by IR, 1 Н NMR and electronic spectroscopy, tensiometry, conductometry, and potentiometry. The critical micelle concentrations, counterionic micellar binding constants, and adsorption parameters at the water–air interface were determined and compared with the respective characteristics of the ligands and conventional amphiphiles

Coherent oscillations in a superconducting tunable flux qubit manipulated without microwaves

We experimentally demonstrate the coherent oscillations of a tunable superconducting flux qubit by manipulating its energy potential with a nanosecond-long pulse of magnetic flux. The occupation probabilities of two persistent current states oscillate at a frequency ranging from 6 GHz to 21 GHz, tunable via the amplitude of the flux pulse. The demonstrated operation mode allows to realize quantum gates which take less than 100 ps time and are thus much faster compared to other superconducting qubits. An other advantage of this type of qubit is its insensitivity to both thermal and magnetic field fluctuations.Comment: 5 pages, 5 figure

Complexes of 1-hexadecyl-4-aza-1-azoniabicyclo[2.2.2]octane bromide with transition metal nitrates. Micelle-forming, solubilizing, and adsorption properties

© 2017, Pleiades Publishing, Ltd. Amphiphilic complexes of 1-hexadecyl-4-aza-1-azoniabicyclo[2.2.2]octane bromide (D-16) with nitrates of transition metals (La 3+ , Cu 2+ , Ni 2+ , and Co 2+ ) have been synthesized and characterized. Absorption spectrophotometry in the UV, visible, and IR regions, as well as 1 Н NMR spectroscopy, have been employed to study their spectral properties in water and organic media. Adsorption properties and micelleforming and solubilizing abilities of the amphiphilic complexes have been investigated in aqueous solutions by the methods of tensiometry and conductometry, as well as by solubilization of a water-insoluble dye (Orange OT). The values of the critical micelle concentration, adsorption parameters at a water/air interface, and solubilization capacity S of complex micelles have been determined. It has been shown that the most pronounced decrease in the critical micelle concentration (as large as two to three times) and differences in the adsorption characteristics and the S values as compared with those of ligand D-16 are observed for complexes of copper and lanthanum. The S values for these complexes are 1.3−2.5 and 3−6.5 times higher than those for D-16 and cetyltrimethylammonium bromide, respectively