Single-Particle Self-Excited Oscillator

Electronic feedback is used to self-excite the axial oscillation of a single electron in a Penning trap. Large, stable, easily detected oscillations arise even in an anharmonic potential. Amplitudes are controlled by adjusting the feedback gain, and frequencies can be made nearly independent of amplitude fluctuations. Quantum jump spectroscopy of a perpendicular cyclotron motion reveals the absolute temperature and amplitude of the self-excited oscillation. The possibility to quickly measure parts per billion frequency shifts could open the way to improved measurements of e-, e+, p, and [overline p] magnetic moments

New Measurement of the Electron Magnetic Moment and the Fine Structure Constant

A measurement using a one-electron quantum cyclotron gives the electron magnetic moment in Bohr magnetons, g/2 = 1.001 159 652 180 73 (28) [0.28 ppt], with an uncertainty 2.7 and 15 times smaller than for previous measurements in 2006 and 1987. The electron is used as a magnetometer to allow lineshape statistics to accumulate, and its spontaneous emission rate determines the correction for its interaction with a cylindrical trap cavity. The new measurement and QED theory determine the fine structure constant, with alpha^{-1} = 137.035 999 084 (51) [0.37 ppb], and an uncertainty 20 times smaller than for any independent determination of alpha.Comment: 4 pages, 4 figure

Cavity Control of a Single-Electron Quantum Cyclotron:\\Measuring the Electron Magnetic Moment

Measurements with a one-electron quantum cyclotron determine the electron magnetic moment, given by $g/2 = 1.001\,159\,652\,180\,73\,(28)\,[0.28~\textrm{ppt}]$, and the fine structure constant, $\alpha^{-1}=137.035\,999\,084\,(51)\,[0.37~\textrm{ppb}]$. Brief announcements of these measurements are supplemented here with a more complete description of the one-electron quantum cyclotron and the new measurement methods, a discussion of the cavity control of the radiation field, a summary of the analysis of the measurements, and a fuller discussion of the uncertainties

Complete methods set for scalable ion trap quantum information processing

Large-scale quantum information processors must be able to transport and maintain quantum information, and repeatedly perform logical operations. Here we demonstrate a combination of all the fundamental elements required to perform scalable quantum computing using qubits stored in the internal states of trapped atomic ions. We quantify the repeatability of a multi-qubit operation, observing no loss of performance despite qubit transport over macroscopic distances. Key to these results is the use of different pairs of beryllium ion hyperfine states for robust qubit storage, readout and gates, and simultaneous trapping of magnesium re-cooling ions along with the qubit ions.Comment: 9 pages, 4 figures. Accepted to Science, and thus subject to a press embarg

Normal modes of trapped ions in the presence of anharmonic trap potentials

We theoretically and experimentally examine the effects of anharmonic terms in the trapping potential for linear chains of trapped ions. We concentrate on two different effects that become significant at different levels of anharmonicity. The first is a modification of the oscillation frequencies and amplitudes of the ions' normal modes of vibration for multi-ion crystals, resulting from each ion experiencing a different curvature in the potential. In the second effect, which occurs with increased anharmonicity or higher excitation amplitude, amplitude-dependent shifts of the normal-mode frequencies become important. We evaluate normal-mode frequency and amplitude shifts, and comment on the implications for quantum information processing and quantum state engineering. Since the ratio of the anharmonic to harmonic terms typically increases as the ion--electrode distance decreases, anharmonic effects will become more significant as ion trap sizes are reduced. To avoid unwanted problems, anharmonicities should therefore be taken into account at the design stage of trap development.Comment: 26 pages, 7 figure

Youth’s Socio-Sexual Competences With Romantic and Casual Sexual Partners

We investigated youth’s self-reported socio-sexual competences (esteem, assertiveness, control, communication) within their most recent sexual partnerships, and explored disparities in these competences between romantic versus casual sexual partnerships, including age and gender differences therein. Data were used from 6,098 Dutch adolescents and young adults (12.1–26.1 years), who participated in a national study on sexual health. Results indicated that being in love and sexual activity frequency were significant confound

Learning with a Drifting Target Concept

We study the problem of learning in the presence of a drifting target concept. Specifically, we provide bounds on the error rate at a given time, given a learner with access to a history of independent samples labeled according to a target concept that can change on each round. One of our main contributions is a refinement of the best previous results for polynomial-time algorithms for the space of linear separators under a uniform distribution. We also provide general results for an algorithm capable of adapting to a variable rate of drift of the target concept. Some of the results also describe an active learning variant of this setting, and provide bounds on the number of queries for the labels of points in the sequence sufficient to obtain the stated bounds on the error rates

Scarce quality assurance documentation in major clinical trial registries for approved medicines used in post-marketing clinical trials

BACKGROUND: This research reviewed major Clinical Trial Registries (CTRs) and assessed the availability of fields on quality assurance for approved medicines used as Investigational Medicinal Products (IMPs) in phase-IV clinical trials. // METHODS: Two reviewers independently assessed CTRs of International Committee of Medical Journal Editors (ICJME) and of WHO platforms. Each CTR was checked by two reviewers on availability of fields on brand name; manufacturer’s name; approval status; approving authority; compliance with Good Manufacturing Practices; and quality testing. In case of discrepancy, consensus was sought between the two reviewers. // RESULTS: Of 19 identified CTRs, 8 and 6 belonged to WHO and ICMJE, respectively, while 5 were equally part of both platforms. All CTRs had an “intervention” field where data on IMPs and IMP comparators are captured. The Canadian CTR used “drug name” rather than “intervention”. The EU, Peruvian, and UK CTRs had fields for “brand name”. But only the EU CTR had fields for “manufacturer’s name”, “approval status”, and “approving authority”. None of the CTRs had fields on “compliance with Good Manufacturing Practices” or “quality testing”. // CONCLUSION: This study demonstrates that none of the CTRs of ICMJE and ICTRP platforms has adequate fields to establish that the source of post-marketing IMPs is of assured quality. This is astonishing given the lengthy requirements in WHO and ICMJE guidelines. Considering the relation between IMP quality and safety of clinical trial participants, the gap of quality assurance fields should be bridged at CTRs concurrently to adjustments of WHO and ICMJE guidelines on CTRs. Specifically, IMP quality testing addressing issues on IMP appearance, impurities, microbial contamination, and dosing should be conducted and reported before, during, and after clinical trial conduct. Until adoption of these measures, the EU CTR should be preferred for registration of phase-IV clinical trials conducted in countries lacking stringent regulatory capacities