Observation of zero-point quantum fluctuations of a single-molecule magnet through the relaxation of its nuclear spin bath

A single-molecule magnet placed in a magnetic field perpendicular to its anisotropy axis can be truncated to an effective two-level system, with easily tunable energy splitting. The quantum coherence of the molecular spin is largely determined by the dynamics of the surrounding nuclear spin bath. Here we report the measurement of the nuclear spin--lattice relaxation in a single crystal of the single-molecule magnet Mn$_{12}$-ac, at $T \approx 30$ mK in perpendicular fields $B_{\perp}$ up to 9 T. Although the molecular spin is in its ground state, we observe an increase of the nuclear relaxation rates by several orders of magnitude up to the highest $B_{\perp}$. This unique finding is a consequence of the zero-point quantum fluctuations of the Mn$_{12}$-ac spin, which allow it to efficiently transfer energy from the excited nuclear spin bath to the lattice. Our experiment highlights the importance of quantum fluctuations in the interaction between an `effective two-level system' and its surrounding spin bath.Comment: 5 pages, 4 figure

Commissioning of the Inner Tracker of the KLOE-2 experiment

The KLOE-2 experiment is undergoing commissioning at the DA$\Phi$NE $e^{+}e^{-}$ collider of the Frascati National Laboratory of the INFN, after the integration of new detectors in the former KLOE apparatus. The Inner Tracker, a very light detector (material budget $<2\%X_{0}$), is one of the new subdetectors and it is composed of 4 cylindrical triple-GEM with a stereo X-V strips/pads readout. The commissioning phase of the Inner Tracker consists in the characterization of the detector response and in its performance evaluation. The method used to evaluate its detection efficiency is reported, together with some preliminary results

3D-melting features of the irreversibility line in overdoped Bi2_2Sr2_2CuO6_6 at ultra-low temperature and high magnetic field

We have measured the irreversible magnetization of an overdoped Bi$_2$Sr$_2$CuO$_6$ single crystal up to B=28 T and down to T=60 mK, and extracted the irreversibility line $B_{\rm irr}(T)$: the data can be interpreted in the whole temperature range as a 3D-anisotropic vortex lattice melting line with Lindemann number $c_{\rm L}=0.13$. We also briefly discuss the applicability of alternative models such as 2D- and quantum melting, and the connection with magnetoresistance experiments.Comment: M2S-HTSC-VI Conference paper (2 pages, 1 figure), using Elsevier style espcrc2.st

Report of the workshop on Aviation Safety/Automation Program

As part of NASA's responsibility to encourage and facilitate active exchange of information and ideas among members of the aviation community, an Aviation Safety/Automation workshop was organized and sponsored by the Flight Management Division of NASA Langley Research Center. The one-day workshop was held on October 10, 1989, at the Sheraton Beach Inn and Conference Center in Virginia Beach, Virginia. Participants were invited from industry, government, and universities to discuss critical questions and issues concerning the rapid introduction and utilization of advanced computer-based technology into the flight deck and air traffic controller workstation environments. The workshop was attended by approximately 30 discipline experts, automation and human factors researchers, and research and development managers. The goal of the workshop was to address major issues identified by the NASA Aviation Safety/Automation Program. Here, the results of the workshop are documented. The ideas, thoughts, and concepts were developed by the workshop participants. The findings, however, have been synthesized into a final report primarily by the NASA researchers

Review of operational aspects of initial experiments utilizing the U.S. MLS

An exercise to support the Federal Aviation Administration in demonstrating the U.S. candidate for an international microwave landing system (MLS) was conducted by NASA. During this demonstration the MLS was utilized to provide the TCV Boeing 737 research airplane with guidance for automatic control during transition from conventional RNAV to MLS RNAV in curved, descending flight; flare; touchdown; and roll-out. Flight profiles, system configuration, displays, and operating procedures used in the demonstration are described, and preliminary results of flight data analysis are discussed. Recent experiences with manually controlled flight in the NAFEC MLS environment are also discussed. The demonstration shows that in automatic three-dimensional flight, the volumetric signal coverage of the MLS can be exploited to enable a commercial carrier class airplane to perform complex curved, descending paths with precision turns into short final approaches terminating in landing and roll-out, even when subjected to strong and gusty tail and cross wind components and severe wind shear

Flight-test evaluation of two electronic display formats for approach to landing under instrument conditions

The results of a flight evaluation of two electronic display formats for the approach to landing under instrument conditions are presented. The evaluation was conducted for a base-line electronic display format and for the same format with runway symbology and track information added. The evaluation was conducted during 3 deg, manual straight-in approaches with and without initial localizer offsets. Flight path tracking performance data and pilot subjective comments were examined with regard to the pilot's ability to capture and maintain localizer and glide slope by using both display formats

A Flight Evaluation of a VTOL Jet Transport Under Visual and Simulated Instrument Conditions

Transition, approach, and vertical landing tests for VTOL transport in terminal are

Observation of the single-electron regime in a highly tunable silicon quantum dot

We report on low-temperature electronic transport measurements of a silicon metal-oxide-semiconductor quantum dot, with independent gate control of electron densities in the leads and the quantum dot island. This architecture allows the dot energy levels to be probed without affecting the electron density in the leads, and vice versa. Appropriate gate biasing enables the dot occupancy to be reduced to the single-electron level, as evidenced by magnetospectroscopy measurements of the ground state of the first two charge transitions. Independent gate control of the electron reservoirs also enables discrimination between excited states of the dot and density of states modulations in the leads.Comment: 4 pages, 3 figures, accepted for Applied Physics Letter

AQUIFER Nano-Electrofuel Energy Economy and Powered Aircraft Operations

The Aqueous, QUick-charging battery Integration For Electric flight Research project is explained and the major subsystems are described, including nano-electric fluid, rim-driven motors, and integration concepts. The nano-electric fluid concept is a new type of aqueous flow battery that could reduce or retire the fire and explosion hazards of conventional batteries and fuel cells. The nano-electric fluid itself could enable energy storage and increased available energy per fuel weight ratios. The rim-driven motor is being developed to improve propulsion system safety and stability and to reduce noise. The rim-driven motor concept could enable motors that are more efficient both electrically and aerodynamically. The Energy Economy of the project concept is presented as a potential renewable or green energy sustainment for utilizing in-place infrastructure. The nano-electric fluid energy charge-use-recharge cycle is presented using renewable energy input from solar, wind, and hydroelectricity. Powered aircraft operations are presented, and the logistics of the new nano-electric fluid technology are explored. Powered aircraft operations topics include weight and balance, fueling, recharging, safety, and derivative considerations

Arrival direction distribution of cosmic rays of energy 10 (18) eV

The Haverah Park air-shower experiment recorded over 8500 events with primary energy 10 to the 18th power eV between 1963 and 1983. An analysis of these events for anisotropies in celestial and galactic coordinates is reported. No very striking anisotropies are observed