Switchable coupling between charge and flux qubits

We propose a hybrid quantum circuit with both charge and flux qubits connected to a large Josephson junction that gives rise to an effective inter-qubit coupling controlled by the external magnetic flux. This switchable inter-qubit coupling can be used to transfer back and forth an arbitrary superposition state between the charge qubit and the flux qubit working at the optimal point. The proposed hybrid circuit provides a promising quantum memory because the flux qubit at the optimal point can store the tranferred quantum state for a relatively long time.Comment: 5 pages, 1 figur

Tissue-specific Accumulation of Flavonoids in Grape Berries is Related to Transcriptional Expression of VvF3′H and VvF3′5′H

The products and the related gene expression of flavonoid metabolism were examined in the skin and pulpof Yan73 (Vitis vinifera L. cv.) grapes, a teinturier variety cultivated in China, and the data were comparedwith those in the skin and pulp of Cabernet Sauvignon (Vitis vinifera L. cv.) grapes, a well-known redvariety. The results showed that, in comparison with the skins of Cabernet Sauvignon, the skins of Yan73berries were characterised by fewer types of flavonols and anthocyanins, a higher level of flavonoids,and a much lower percentage of 3′-hydroxylated flavonols. Flavonoid metabolism was also present in thepulp of Yan73, and the percentages of 3′-hydroxylated flavonols and 3′-hydroxylated flavan-3-ols weresignificantly higher than the percentages of their corresponding 3′,5′-hydroxylated forms. Only flavan-3-ols were found in the pulp of Cabernet Sauvignon. The expression of VvmybA1 exhibited a co-ordinationwith the accumulation of anthocyanins in the pulp of the teinturier cultivar, which showed great similarityto that in the skin. A good correlation was found between the expression of VvF3′H and 3′-hydroxylatedflavonoids, as well as between the expression of VvF3′5′H and 3′,5′-hydroxylated flavonoids in the skin andpulp of the grape berries. It is suggested that tissue-specific accumulation of flavonoids in grape berries isrelated to the transcriptional expression of VvF3′H and VvF3′5′H

Leveraging process data to assess adults' problem-solving skills: Using sequence mining to identify behavioral patterns across digital tasks

This paper illustrates how process data can be used to identify behavioral patterns in a computer-based problem-solving assessment. Using sequence-mining techniques, we identify patterns of behavior across multiple digital tasks from the sequences of actions undertaken by respondents. We then examine how respondents’ action sequences (which we label “strategies”) differ from optimal strategies. In our application, optimality is defined ex-ante as the sequence of actions that content experts involved in the development of the assessment tasks identified as most efficient to solve the task given the range of possible actions available to test-takers. Data on 7462 respondents from five countries (the United Kingdom, Ireland, Japan, the Netherlands, and the United States) participating in the Problem Solving in Technology-Rich Environment (PSTRE) assessment, administered as part of the OECD Programme for the International Assessment of Adult Competencies (PIAAC), indicate that valuable insights can be derived from the analysis of process data. Adults who follow optimal strategies are more likely to obtain high scores in the PSTRE assessment, while low performers consistently adopt strategies that are very distant from optimal ones. Very few high performers are able to solve the items in an efficient way, i.e. by minimizing the number of actions and by avoiding undertaking unnecessary or redundant actions. Women and adults above the age of 40 are more likely to adopt sub-optimal problem-solving strategies

A Novel Large Moment Antiferromagnetic Order in K0.8Fe1.6Se2 Superconductor

The discovery of cuprate high Tc superconductors has inspired searching for unconventional su- perconductors in magnetic materials. A successful recipe has been to suppress long-range order in a magnetic parent compound by doping or high pressure to drive the material towards a quantum critical point, which is replicated in recent discovery of iron-based high TC superconductors. The long-range magnetic order coexisting with superconductivity has either a small magnetic moment or low ordering temperature in all previously established examples. Here we report an exception to this rule in the recently discovered potassium iron selenide. The superconducting composition is identified as the iron vacancy ordered K0.8Fe1.6Se2 with Tc above 30 K. A novel large moment 3.31 {\mu}B/Fe antiferromagnetic order which conforms to the tetragonal crystal symmetry has the unprecedentedly high an ordering temperature TN = 559 K for a bulk superconductor. Staggeredly polarized electronic density of states thus is suspected, which would stimulate further investigation into superconductivity in a strong spin-exchange field under new circumstance.Comment: 5 figures, 5 pages, and 2 tables in pdf which arXiv.com cannot tak

Synthesis, Structure and Magnetic Properties of New Layered Iron-Oxychalcogenide Na2Fe2OSe2

A new layered iron-oxychalcogenide Na2Fe2OSe2 has been synthesized and structurally characterized by powder X-ray diffraction. The structure is formed by alternate stacking of the newly discovered [Fe2OSe2] blocks and double layers of Na. Conductivity study shows that Na2Fe2OSe2 is a semiconductor with activation energy of 0.26 eV. Magnetic susceptibility and heat capacity measurements reveal an antiferromagnetic phase transition occurs at TN=73 K. A broad maximum of magnetic susceptibility and a slow decay of the specific heat above TN, arises as a result of two-dimensional short-range spin correlation.Comment: 4 pages, 4 figure