Detection of mechanical resonance of a single-electron transistor by direct current

We have suspended an Al based single-electron transistor whose island can resonate freely between the source and drain leads forming the clamps. In addition to the regular side gate, a bottom gate with a larger capacitance to the SET island is placed underneath to increase the SET coupling to mechanical motion. The device can be considered as a doubly clamped Al beam that can transduce mechanical vibrations into variations of the SET current. Our simulations based on the orthodox model, with the SET parameters estimated from the experiment, reproduce the observed transport characteristics in detail.Comment: 4 pages, 3 figure

The Elastic Moduli of Thick Composites

Thick composites are in use in critical applications and are proposed for still others. It is important to measure the elastic moduli of thick composites for two reasons: (1) for design data on stiffness, and (2) for prediction of feasible wave paths for ultrasonic waves for NDE. Previously only relatively thin composites of relatively simple symmetries have been measured for their elastic moduli. Now, it is becoming necessary to measure thick composites of feasible engineering lay-ups. These generally provide the complexity of orthorhombic symmetry locally in a specimen combined with curvature in the gross structure. In this work, specimens cut from thick structures will be treated in the same way as crystals to measure the elastic moduli by means of ultrasonic wave velocities. Results on one structure will be presented. Difficulties will be analyzed

Spectroscopy of superconducting charge qubits coupled by a Josephson inductance

We have designed and experimentally implemented a circuit of inductively-coupled superconducting charge qubits, where a Josephson junction is used as an inductance, and the coupling between the qubits is controlled by an applied magnetic flux. Spectroscopic measurements on the circuit are in good agreement with theoretical calculations. We observed anticrossings which originate from the coupling between the qubit and the plasma mode of the Josephson junction. Moreover, the size of the anticrossing depends on the external magnetic flux, which demonstrates the controllability of the coupling.Comment: Accepted for publication in PRB. 11 pages, 7 figure

Issues in determining alpha_s from hadronic tau decay and electroproduction data

We discuss some key issues associated with duality-violating and non-perturbative OPE contributions to the theoretical representations of light quark current-current two-point functions and relevant to precision determinations of alpha_s from hadronic tau decay and electroproduction cross-section data. We demonstrate that analyses with an explicit representation of duality-violating effects are required to bring theoretical errors in such extractions under control, motivating the accompanying paper in these proceedings, which presents the results of such an analysis.Comment: 5 pages, 4 figures. Prepared for the Proceedings of the International Workshop on e+e- collisions from Phi to Psi (PHIPSI11), Sep. 19-22, 2011, BINP, Novosibirsk, Russi

Single-shot measurement of the Josephson charge qubit

We demonstrate single-shot readout of quantum states of the Josephson charge qubit. The quantum bits are transformed into and stored as classical bits (charge quanta) in a dynamic memory cell - a superconducting island. The transformation of state |1> (differing form state |0> by an extra Cooper pair) is a result of a controllable quasiparticle tunneling to the island. The charge is then detected by a conventional single-electron transistor, electrostatically decoupled from the qubit. We study relaxation dynamics in the system and obtain the readout efficiency of 87% and 93% for |1> and |0> states, respectively.Comment: submitted to Rapid Communications of Phys. Rev. B (february 2004

Association of C-reactive protein and metabolic risk with cognitive effects of lurasidone in patients with schizophrenia

BACKGROUND: Accumulating evidence has implicated insulin resistance and inflammation in the pathophysiology of cognitive impairments associated with neuropsychiatric disorders. This post-hoc analysis based on a placebo-controlled trial investigated the effect of inflammation (indexed by CRP) and metabolic risk factors on cognitive performance in patients with schizophrenia treated with lurasidone. METHODS: Acutely exacerbated patients with schizophrenia were randomized to lurasidone (80 or 160 mg/day), quetiapine XR 600 mg/day, or placebo. A wide range CRP test and a cognitive assessment using the CogState computerized battery were performed at baseline and week 6 study endpoint. Associations between log-transformed CRP, high density lipoprotein (HDL), homeostatic model assessment of insulin resistance (HOMA-IR) and treatment response were evaluated. RESULTS: CRP combined with HDL, triglyceride-to-HDL (TG/HDL) ratio, or HOMA-IR at study baseline were significant moderators of the improvement in cognitive performance associated with lurasidone 160 mg/day (vs. placebo) treatment (p \u3c .05). Greater placebo-corrected treatment effect size on the CogState composite score was observed for patients in the lurasidone 160 mg/day treatment group who had either low CRP and high HDL (d = 0.43), or low CRP and low HOMA-IR (d = 0.46). Interactive relationships between CRP, HDL, TG/HDL, HOMA-IR and the antipsychotic efficacy of lurasidone or quetiapine XR were not significant. There were no significant associations between antipsychotic treatment and changes in CRP level at study endpoint. CONCLUSIONS: Findings of this post-hoc analysis based on a placebo-controlled trial in patients with schizophrenia suggest that baseline CRP level combined with measures of metabolic risk significantly moderated the improvement in cognitive performance associated with lurasidone 160 mg/day (vs. placebo) treatment. Our findings underscore the importance of maintaining a low metabolic risk profile in patients with schizophrenia

Coherent quantum phase slip

A hundred years after discovery of superconductivity, one fundamental prediction of the theory, the coherent quantum phase slip (CQPS), has not been observed. CQPS is a phenomenon exactly dual to the Josephson effect: whilst the latter is a coherent transfer of charges between superconducting contacts, the former is a coherent transfer of vortices or fluxes across a superconducting wire. In contrast to previously reported observations of incoherent phase slip, the CQPS has been only a subject of theoretical study. Its experimental demonstration is made difficult by quasiparticle dissipation due to gapless excitations in nanowires or in vortex cores. This difficulty might be overcome by using certain strongly disordered superconductors in the vicinity of the superconductor-insulator transition (SIT). Here we report the first direct observation of the CQPS in a strongly disordered indium-oxide (InOx) superconducting wire inserted in a loop, which is manifested by the superposition of the quantum states with different number of fluxes. Similarly to the Josephson effect, our observation is expected to lead to novel applications in superconducting electronics and quantum metrology.Comment: 14 pages, 3 figure

Superchemistry: dynamics of coupled atomic and molecular Bose-Einstein condensates

We analyze the dynamics of a dilute, trapped Bose-condensed atomic gas coupled to a diatomic molecular Bose gas by coherent Raman transitions. This system is shown to result in a new type of `superchemistry', in which giant collective oscillations between the atomic and molecular gas can occur. The phenomenon is caused by stimulated emission of bosonic atoms or molecules into their condensate phases