Superpressure balloon flights from Christchurch, New Zealand, July 1968 - December 1969

Strain gages on superpressure balloon flights from Christchurch, New Zealand - Jul. 1968 to Dec. 196

A quantitative study of spin noise spectroscopy in a classical gas of 41^{41}K atoms

We present a general derivation of the electron spin noise power spectrum in alkali gases as measured by optical Faraday rotation, which applies to both classical gases at high temperatures as well as ultracold quantum gases. We show that the spin-noise power spectrum is determined by an electron spin-spin correlation function, and we find that measurements of the spin-noise power spectra for a classical gas of $^{41}$K atoms are in good agreement with the predicted values. Experimental and theoretical spin noise spectra are directly and quantitatively compared in both longitudinal and transverse magnetic fields up to the high magnetic field regime (where Zeeman energies exceed the intrinsic hyperfine energy splitting of the $^{41}$K ground state)

Spin noise spectroscopy to probe quantum states of ultracold fermionic atomic gases

Ultracold alkali atoms provide experimentally accessible model systems for probing quantum states that manifest themselves at the macroscopic scale. Recent experimental realizations of superfluidity in dilute gases of ultracold fermionic (half-integer spin) atoms offer exciting opportunities to directly test theoretical models of related many-body fermion systems that are inaccessible to experimental manipulation, such as neutron stars and quark-gluon plasmas. However, the microscopic interactions between fermions are potentially quite complex, and experiments in ultracold gases to date cannot clearly distinguish between the qualitatively different microscopic models that have been proposed. Here, we theoretically demonstrate that optical measurements of electron spin noise -- the intrinsic, random fluctuations of spin -- can probe the entangled quantum states of ultracold fermionic atomic gases and unambiguously reveal the detailed nature of the interatomic interactions. We show that different models predict different sets of resonances in the noise spectrum, and once the correct effective interatomic interaction model is identified, the line-shapes of the spin noise can be used to constrain this model. Further, experimental measurements of spin noise in classical (Boltzmann) alkali vapors are used to estimate the expected signal magnitudes for spin noise measurements in ultracold atom systems and to show that these measurements are feasible

A cascade of magnetic field induced spin transitions in LaCoO3

We present magnetization and magnetostriction studies of the insulating perovskite LaCoO3 in magnetic fields approaching 100 T. In marked contrast with expectations from single-ion models, the data reveal two distinct first-order spin transitions and well-defined magnetization plateaux. The magnetization at the higher plateau is only about half the saturation value expected for spin-1 Co3+ ions. These findings strongly suggest collective behavior induced by strong interactions between different electronic -- and therefore spin -- configurations of Co3+ ions. We propose a model of these interactions that predicts crystalline spin textures and a cascade of four magnetic phase transitions at high fields, of which the first two account for the experimental data.Comment: 5 pages + supplementary materials, 5 figure

Dirac: A campaign of experiments to study physics and chemistry at ultrahigh magnetic fields

We present an overview of the Dirac experimental campaign conducted at Los Alamos in spring of 1996. The name was chosen in recognition of P.A.M. Dirac`s monumental contributions to quantum theory, which affected every aspect of the science we planned to investigate. We show how the various collaborations were put together, discuss some of the difficulties of collecting data in rapidly changing magnetic fields, describe the motivation, packaging, and integration of experiments, and give an exceedingly preliminary discussion of some of the results

A Transition Model from Web of Things to Speech of Intelligent Things in a Smart Education System

Several terms have been used to describe Internet of Things; Web of Things (WoT) is a term which can be used interchangeability and it is referred to as the capability of devices to interconnect to the World Wide Web and sharing the information and data to one another. WoT has been mentioned in the literature to improve interconnection between devices at all times. In WoT, two different modes of communication which are generally mentioned in previous studies include person-to-thing (or thing-to-person) and thing-to-thing. This paper presents an architecture for transiting from WoT to speech-enabled WoT known as Speech of Intelligent Things (SoIT). The system employs a combination of technologies such as system design, server-side scripting, speech-based system tools, and data management in developing the SoIT prototype system as a third mode of communication. This paper illustrates a scenario whereby remote monitoring and controlling of WoT devices within the university campus might be difficult to manage by only using the modes discussed in the literature. An evolution of WoT to SoIT was realized using speech technology to provide a prototype system. Technical implications involve using a telephone by connecting an object telephone number (OTN) and dial WoT objects and establish a control mechanism. The research limitation is mainly the cost of dialing an OTN number. The contribution of this paper is to favor and encourage the use of speech technology to enhance the convenience of communication between WoT devices within the school campus

Experimental determination of B-T phase diagram of YBa_2Cu_3O_7-d to 150T for B perpendicular to c

The B-T phase diagram for thin film YBa_2Cu_3O_7-d with B parallel to the superconducting layers has been constructed from GHz transport measurements to 150T. Evidence for a transition from a high T regime dominated by orbital effects, to a low T regime where paramagnetic limiting drives the quenching of superconductivity, is seen. Up to 110T the upper critical field is found to be linear in T and in remarkable agreement with extrapolation of the longstanding result of Welp et al arising from magnetisation measurements to 6T. Beyond this a departure from linear behaviour occurs at T=74K, where a 3D-2D crossover is expected to occur.Comment: 4 pages, 4 figure

Fully connected bulk Pb 1−

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Magnetic susceptibility of the normal-superconducting transition in high-purity single-crystal α-uranium

We report complex ac magnetic susceptibility measurements of a superconducting transition in very high-quality single-crystal alpha-uranium using microfabricated coplanar magnetometers. We identify an onset of superconductivity at Tapproximate to0.7 K in both the real and imaginary components of the susceptibility which is confirmed by resistivity data. A superconducting volume fraction argument, based on a comparison with a calibration YBa2Cu3O7-delta sample, indicates that superconductivity in these samples may be filamentary. Our data also demonstrate the sensitivity of the coplanar micro-magnetometers, which are ideally suited to measurements in pulsed magnetic fields exceeding 100 T