An Introduction to Superconducting Qubits and Circuit Quantum Electrodynamics

A subset of the concepts of circuit quantum electrodynamics are reviewed as a reference to the Axion Dark Matter Experiment (ADMX) community as part of the proceedings of the 2nd Workshop on Microwave Cavities and Detectors for Axion Research. The classical Lagrangians and Hamiltonians for an LC circuit are discussed along with black box circuit quantization methods for a weakly anharmonic qubit coupled to a resonator or cavity

Muskuläre Biomechanik in der Sprunggelenkprothetik

Zusammenfassung: Das Ziel dieser orthopädisch-biomechanischen Studie war die Evaluation der Muskelfunktion von Patienten, bei welchen infolge unilateraler, schwerer Arthrose am oberen Sprunggelenk (OSG) eine Prothese eingesetzt wurde. Bei 10Patienten wurde vor und 1Jahr nach Implantation einer OSG-Prothese eine orthopädische und biomechanische Untersuchung durchgeführt. Dabei wurden der Schmerzscore, der "American Orthopaedic Foot and Ankle Society"- (AOFAS-)Ankle-Score, der Bewegungsumfang (ROM) des Sprunggelenks und der Unterschied zwischen dem Umfang des Unterschenkels des betroffenen und des kontralateralen gesunden Beins gemessen. Die biomechanische Beurteilung bestand aus einer simultanen Messung des maximal willkürlichen, isometrischen Drehmoments bei Plantarflexion und Dorsalextension des OSG sowie aus einem Oberflächenelektromyogramm (EMG; mittlere Frequenz und Intensität) von 4 Unterschenkelmuskeln: Tibialis anterior (TA), Gastrocnemius medialis (GM), Soleus (SO) und Peroneus longus (PL). Im Vergleich zur präoperativen Evaluation verbesserten sich der Schmerzscore von 6,7 auf 0,8Punkte, der AOFAS-Ankle-Score von 35,6 auf 92,3Punkte und der ROM nach Implantation der OSG-Prothese signifikant. Die mittlere Differenz des Unterschenkelumfangs zwischen den beiden Beinen nahm von 2,2cm auf 1,4cm ab. Dies war jedoch nicht signifikant. Das mittlere Drehmoment des betroffenen Sprunggelenks bei Dorsalextension stieg von 17,0 auf 25,8Nm und bei Plantarflexion von 15,7 auf 24,6Nm signifikant an. Bei der 1-Jahres-Nachkontrolle war die mittlere EMG-Frequenz in allen atrophischen Muskeln tiefer als bei den gesunden Muskeln der kontralateralen Seite. Ein Unterschied der mittleren EMG-Intensität zur kontralateralen gesunden Seite konnte nicht verifiziert werden. Daraus kann gefolgert werden, dass Patienten mit symptomatischer OSG-Arthrose mit einer Prothese eine bessere Funktion erlangen; 1Jahr nach der Operation entspricht dies jedoch nicht dem Ausmaß derjenigen des kontralateralen gesunden Bein

3-D kinematic comparison of treadmill and overground running.

Studies investigating the mechanics of human movement are often conducted using the treadmill. The treadmill is an attractive device for the analysis of human locomotion. Studies comparing overground and treadmill running have analyzed discrete variables, however differences in excursion from footstrike to peak angle and range of motion during stance have yet to be examined. This study aimed to examine the 3-D kinematics of the lower extremities during overground and treadmill locomotion to determine the extent to which the two modalities differ. Twelve participants ran at 4.0m/s in both treadmill and overground conditions. 3-D angular kinematic parameters during the stance phase were collected using an eight camera motion analysis system. Hip, knee and ankle joint kinematics were quantified in the sagittal, coronal and transverse planes, then compared using paired t-tests. Of the parameters analyzed hip flexion at footstrike 12° hip range of motion 17°, peak hip flexion 12.7°, hip transverse plane range of motion 8° peak knee flexion 5° and peak ankle excursion range 6.6°, coronal plane ankle angle at toe-off 6.5° and peak ankle eversion 6.3° were found to be significantly different. These results lead to the conclusion that the mechanics of treadmill locomotion cannot be generalized to overground

Implementing and characterizing precise multi-qubit measurements

There are two general requirements to harness the computational power of quantum mechanics: the ability to manipulate the evolution of an isolated system and the ability to faithfully extract information from it. Quantum error correction and simulation often make a more exacting demand: the ability to perform non-destructive measurements of specific correlations within that system. We realize such measurements by employing a protocol adapted from [S. Nigg and S. M. Girvin, Phys. Rev. Lett. 110, 243604 (2013)], enabling real-time selection of arbitrary register-wide Pauli operators. Our implementation consists of a simple circuit quantum electrodynamics (cQED) module of four highly-coherent 3D transmon qubits, collectively coupled to a high-Q superconducting microwave cavity. As a demonstration, we enact all seven nontrivial subset-parity measurements on our three-qubit register. For each we fully characterize the realized measurement by analyzing the detector (observable operators) via quantum detector tomography and by analyzing the quantum back-action via conditioned process tomography. No single quantity completely encapsulates the performance of a measurement, and standard figures of merit have not yet emerged. Accordingly, we consider several new fidelity measures for both the detector and the complete measurement process. We measure all of these quantities and report high fidelities, indicating that we are measuring the desired quantities precisely and that the measurements are highly non-demolition. We further show that both results are improved significantly by an additional error-heralding measurement. The analyses presented here form a useful basis for the future characterization and validation of quantum measurements, anticipating the demands of emerging quantum technologies.Comment: 10 pages, 5 figures, plus supplemen

Effect of the look-up line on the gaze and head orientation of elite ice hockey players

A “look-up-line” (LUL) has been proposed for ice hockey, which is an orange 1 m (40 in) warning line (WL) painted on the ice at the base of the boards. The LUL purports to provide an early warning to players to keep their head up prior to, and as they are being checked. We determined if players looked-up more on a rink with the LUL compared to a traditional Control rink. Elite offensive (O) and defensive (D) players competed 1 vs 1, while wearing an eye tracker that recorded their quiet eye (QE) and fixation tracking (F-T) and an electro-goniometer that measured head angle. External cameras recorded skate duration during four skate phases: P1 preparation, P2 decision-making, P3 cut to boards, P4 contact. The QE was the final fixation prior to contact between O and D as they skated toward and across the WL during P3 and P4. Skate phase durations (%) did not differ by rink or rink by position. More QE and F-T occurred on the WL on the LUL rink than on the Control. The expected increase in head angle on the LUL rink did not occur during P3 or P4. Post-hoc results also showed O and D skated further from the boards on the LUL rink, suggesting the players preferred to control the puck on white ice, rather than the orange color of the LUL rink. More research is needed to determine if these results apply to the competitive setting

Which executive functioning deficits are associated with AD/HD, ODD/CD and comorbid AD/HD+ODD/CD?

Item does not contain fulltextThis study investigated (1) whether attention deficit/hyperactivity disorder (AD/HD) is associated with executive functioning (EF) deficits while controlling for oppositional defiant disorder/conduct disorder (ODD/CD), (2) whether ODD/CD is associated with EF deficits while controlling for AD/HD, and (3)~whether a combination of AD/HD and ODD/CD is associated with EF deficits (and the possibility that there is no association between EF deficits and AD/HD or ODD/CD in isolation). Subjects were 99~children ages 6–12 years. Three putative domains of EF were investigated using well-validated tests: verbal fluency, working memory, and planning. Independent of ODD/CD, AD/HD was associated with deficits in planning and working memory, but not in verbal fluency. Only teacher rated AD/HD, but not parent rated AD/HD, significantly contributed to the prediction of EF task performance. No EF deficits were associated with ODD/CD. The presence of comorbid AD/HD accounts for the EF deficits in children with comorbid AD/HD+ODD/CD. These results suggest that EF deficits are unique to AD/HD and support the model proposed by R. A. Barkley (1997).17 p

The opposites task: Using general rules to test cognitive flexibility in preschoolers

A brief narrative description of the journal article, document, or resource. Executive functions play an important role in cognitive development, and during the preschool years especially, children's performance is limited in tasks that demand flexibility in their behavior. We asked whether preschoolers would exhibit limitations when they are required to apply a general rule in the context of novel stimuli on every trial (the "opposites" task). Two types of inhibitory processing were measured: response interference (resistance to interference from a competing response) and proactive interference (resistance to interference from a previously relevant rule). Group data show 3-year-olds have difficulty inhibiting prepotent tendencies under these conditions, whereas 5-year-olds' accuracy is near ceiling in the task. (Contains 4 footnotes and 1 table.

Impact testing to determine the mechanical properties of articular cartilage in isolation and on bone

The original publication is available at www.springerlink.comNon peer reviewedPostprin

A Single Laser System for Ground-State Cooling of 25-Mg+

We present a single solid-state laser system to cool, coherently manipulate and detect $^{25}$Mg$^+$ ions. Coherent manipulation is accomplished by coupling two hyperfine ground state levels using a pair of far-detuned Raman laser beams. Resonant light for Doppler cooling and detection is derived from the same laser source by means of an electro-optic modulator, generating a sideband which is resonant with the atomic transition. We demonstrate ground-state cooling of one of the vibrational modes of the ion in the trap using resolved-sideband cooling. The cooling performance is studied and discussed by observing the temporal evolution of Raman-stimulated sideband transitions. The setup is a major simplification over existing state-of-the-art systems, typically involving up to three separate laser sources

Why are we not flooded by involuntary thoughts about the past and future? Testing the cognitive inhibition dependency hypothesis

© The Author(s) 2018In everyday life, involuntary thoughts about future plans and events occur as often as involuntary thoughts about the past. However, compared to involuntary autobiographical memories (IAMs), such episodic involuntary future thoughts (IFTs) have become a focus of study only recently. The aim of the present investigation was to examine why we are not constantly flooded by IFTs and IAMs given that they are often triggered by incidental cues while performing undemanding activities. One possibility is that activated thoughts are suppressed by the inhibitory control mechanism, and therefore depleting inhibitory control should enhance the frequency of both IFTs and IAMs. We report an experiment with a between-subjects design, in which participants in the depleted inhibition condition performed a 60-min high-conflict Stroop task before completing a laboratory vigilance task measuring the frequency of IFTs and IAMs. Participants in the intact inhibition condition performed a version of the Stroop task that did not deplete inhibitory control. To control for physical and mental fatigue resulting from performing the 60-min Stroop tasks in experimental conditions, participants in the control condition completed only the vigilance task. Contrary to predictions, the number of IFTs and IAMs reported during the vigilance task, using the probe-caught method, did not differ across conditions. However, manipulation checks showed that participants’ inhibitory resources were reduced in the depleted inhibition condition, and participants were more tired in the experimental than in the control conditions. These initial findings suggest that neither inhibitory control nor physical and mental fatigue affect the frequency of IFTs and IAMs.Peer reviewedFinal Published versio