Electromechanical Quantum Simulators

Digital quantum simulators are among the most appealing applications of a quantum computer. Here we propose a universal, scalable, and integrated quantum computing platform based on tunable nonlinear electromechanical nano-oscillators. It is shown that very high operational fidelities for single and two qubits gates can be achieved in a minimal architecture, where qubits are encoded in the anharmonic vibrational modes of mechanical nanoresonators, whose effective coupling is mediated by virtual fluctuations of an intermediate superconducting artificial atom. An effective scheme to induce large single-phonon nonlinearities in nano-electromechanical devices is explicitly discussed, thus opening the route to experimental investigation in this direction. Finally, we explicitly show the very high fidelities that can be reached for the digital quantum simulation of model Hamiltonians, by using realistic experimental parameters in state-of-the art devices, and considering the transverse field Ising model as a paradigmatic example.Comment: 14 pages, 8 figure

The Importance of Suspension Stability for the Hot-wire Measurements of Thermal Conductivity of Colloidal Suspensions.

The development of advanced heat transfer fluids with enhanced thermal conductivity is essential to improve the effective heat transfer behavior of conventional coolants. Thermal conductivity enhancement has been reported for colloidal suspensions formulated with different nanoparticles. Reliable thermal conductivity measurement requires that the suspension is stable against sedimentation during the measurement since particle sedimentation may effect the experimental results. The present study proposes a criterion to ensure that thermal conductivity data is independent of the particle sedimentation. A measuring device based on the transient hot-wire method is designed to allow vertical and horizontal thermal conductivity data collection. Our investigation shows that the thermal conductivity measurements in the horizontal and vertical configurations are almost identical when the colloidal suspension is stable while they differ for unstable systems

Structure and dynamics of catalytically competent but labile paramagnetic metal-hydrides: The Ti(iii)-H in homogeneous olefin polymerization

Metal hydride complexes find widespread application in catalysis and their properties are often understood on the basis of the available crystal structures. However, some catalytically relevant metal hydrides are only spontaneously formed in situ, cannot be isolated in large quantities or crystallised and their structure is therefore ill defined. One such example is the paramagnetic Ti(iii)-hydride involved in homogeneous Ziegler–Natta catalysis, formed upon activation of CpTi(iv)Cl(3) with modified methylalumoxane (MMAO). In this contribution, through a combined use of electron paramagnetic resonance (EPR), electron-nuclear double resonance (ENDOR) and hyperfine sublevel correlation (HYSCORE) spectroscopies we identify the nature of the ligands, their bonding interaction and the extent of the spin distribution. From the data, an atomistic and electronic model is proposed, which supports the presence of a self-assembled ion pair between a cationic terminal Ti-hydride and an aluminate anion, with a hydrodynamic radius of ca. 16 Å

Decalcifying efficacy of different irrigating solutions: effect of cetrimide addition

Abstract: The objective of the present study was to evaluate and com-pare the influence of cetrimide on decalcifying capability of different irrigating solutions. Fifteen maxillary central incisor teeth has been col-lected. The canals were prepared in order to obtain four samples from each root. The specimens were randomly divided into 6 experimental groups (n=10) according to tested irrigating agents. Irrigating agents consisted in different composition of EDTA and citric acid solutions, addicted or not with cetrimide. Each specimen was submitted to three successive 5-min immersions in each solution. After exposures, the concentration of Ca2+ extracted was measured by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Data were analysed by means of Kruskal Wallis and Mann Whitney tests. Significance was predetermined at p < 0.05. For all irrigants, the amounts of Ca2+ extract-ed from root canal dentin samples at 10 minutes were not significantly different from values reported after 15 minutes respectively. Therefore, for all irrigants tested, 10 minutes of application are sufficient to obtain maximum Ca2+ release. Moreover citric acid based agents observed a higher release of Ca2+. The addition of cetrimide did not affect the de-calcifying capability of the EDTA and citric acid solutions.Keywords: Chelating Agents; Dentin; Dentistry; Endodontics

Radiofrequency to Microwave Coherent Manipulation of an Organometallic Electronic Spin Qubit Coupled to a Nuclear Qudit

[Image: see text] We report here a comprehensive characterization of a 3d organometallic complex, [V(Cp)(2)Cl(2)] (Cp = cyclopentadienyl), which can be considered as a prototypical multilevel nuclear qudit (nuclear spin I = 7/2) hyperfine coupled to an electronic qubit (electronic spin S = 1/2). By combining complementary magnetic resonant techniques, such as pulsed electron paramagnetic resonance (EPR) and broadband nuclear magnetic resonance (NMR), we extensively characterize its Spin Hamiltonian parameters and its electronic and nuclear spin dynamics. Moreover, we demonstrate the possibility to manipulate the qubit–qudit multilevel structure by resonant microwave and radiofrequency pulses, driving coherent Rabi oscillations between targeted electronuclear states. The obtained results demonstrate that this simple complex is a promising candidate for quantum computing applications

Radiofrequency to Microwave Coherent Manipulation of an Organometallic Electronic Spin Qubit Coupled to a Nuclear Qudit

We report here a comprehensive characterization of a 3d organometallic complex, [V(Cp)2Cl2] (Cp = cyclopentadienyl), which can be considered as a prototypical multilevel nuclear qudit (nuclear spin I = 7/2) hyperfine coupled to an electronic qubit (electronic spin S = 1/2). By combining complementary magnetic resonant techniques, such as pulsed electron paramagnetic resonance (EPR) and broadband nuclear magnetic resonance (NMR), we extensively characterize its Spin Hamiltonian parameters and its electronic and nuclear spin dynamics. Moreover, we demonstrate the possibility to manipulate the qubit-qudit multilevel structure by resonant microwave and radiofrequency pulses, driving coherent Rabi oscillations between targeted electronuclear states. The obtained results demonstrate that this simple complex is a promising candidate for quantum computing applications

Effectiveness of traditional meditation retreats: A systematic review and meta-analysis

BACKGROUND: An increasing number of studies are investigating traditional meditation retreats. Very little, however, is known about their effectiveness. OBJECTIVE: To evaluate the effectiveness of meditation retreats on improving psychological outcomes in general population. DATA SOURCES: A systematic review of studies published in journals or as dissertations in PSYCINFO, PUBMED, CINAHL or Web of Science from the first available date until October 22, 2016. REVIEW METHODS: A total of 20 papers (21 studies, N = 2912) were included. RESULTS: Effect-size estimates of outcomes combined suggested that traditional meditation retreats are moderately effective in pre-post analyses (n = 19; Hedge's g = 0.45; 95% CI [0.35, 0.54], p < 0.00001) and in analyses comparing retreats to controls (n = 14; Hedge's g = 0.49; 95% CI [0.36, 0.61], p < 0.00001). Results were maintained at follow-up. No differences were observed between meditation styles. Results suggested large effects on measures of anxiety, depression and stress, and moderate effects on measures of emotional regulation and quality of life. As to potential mechanisms of actions, results showed large effects on measures of mindfulness and compassion, and moderate effects on measures of acceptance. In addition, changes in mindfulness levels strongly moderated clinical effect sizes. However, heterogeneity was significant among trials, probably due to differences in study designs, types and duration of the retreats and assessed outcomes, limiting therefore the implications of the results. CONCLUSION: Meditation retreats are moderately to largely effective in reducing depression, anxiety, stress and in ameliorating the quality of life of participants

Categorical and dimensional approaches in the evaluation of the relationship between attachment and personality disorders: An empirical study

Although several studies have highlighted the relationship between attachment states of mind and personality disorders (PD), their findings have not been consistent, possibly due to the application of the traditional taxonomic classification model of attachment. A more recently developed dimensional classification of attachment representations, including more specific aspects of trauma-related representations, may have advantages. In this study we compare specific associations and predictive power of the categorical attachment and dimensional models applied to 230 Adult Attachment Interview transcripts obtained from personality disordered and non-psychiatric subjects. We also investigate the role that current levels of psychiatric distress may have in the prediction of PD. The results showed that both models predict the presence of PD, with the dimensional approach doing better in discriminating overall diagnosis of PD. However, both models are less helpful in discriminating specific PD diagnostic subtypes. Current psychiatric distress was found to be the most consistent predictor of PD capturing a large share of the variance and obscuring the role played by attachment variables. The results suggest that attachment parameters correlate with the presence of PD alone and has no specific associations with particular PD subtypes when current psychiatric distress is taken into account