3,242 research outputs found
Quantum noise limited interferometric measurement of atomic noise: towards spin squeezing on the Cs clock transition
We investigate theoretically and experimentally a nondestructive
interferometric measurement of the state population of an ensemble of laser
cooled and trapped atoms. This study is a step towards generation of (pseudo-)
spin squeezing of cold atoms targeted at the improvement of the Caesium clock
performance beyond the limit set by the quantum projection noise of atoms. We
calculate the phase shift and the quantum noise of a near resonant optical
probe pulse propagating through a cloud of cold 133Cs atoms. We analyze the
figure of merit for a quantum non-demolition (QND) measurement of the
collective pseudo-spin and show that it can be expressed simply as a product of
the ensemble optical density and the pulse integrated rate of the spontaneous
emission caused by the off-resonant probe light. Based on this, we propose a
protocol for the sequence of operations required to generate and utilize spin
squeezing for the improved atomic clock performance via a QND measurement on
the probe light. In the experimental part we demonstrate that the
interferometric measurement of the atomic population can reach the sensitivity
of the order of N_at^1/2 in a cloud of N_at cold atoms, which is an important
benchmark towards the experimental realisation of the theoretically analyzed
protocol.Comment: 12 pages and 9 figures, accepted to Physical Review
Addressing inequality in healthy eating among young people at vocational schools:assessing stakeholder engagement in a Whole Health & Whole School Intervention
An Enhanced Nonlinear Critical Gradient for Electron Turbulent Transport due to Reversed Magnetic Shear
The first nonlinear gyrokinetic simulations of electron internal transport
barriers (e-ITBs) in the National Spherical Torus Experiment show that reversed
magnetic shear can suppress thermal transport by increasing the nonlinear
critical gradient for electron-temperature-gradient-driven turbulence to three
times its linear critical value. An interesting feature of this turbulence is
nonlinearly driven off-midplane radial streamers. This work reinforces the
experimental observation that magnetic shear is likely an effective way of
triggering and sustaining e-ITBs in magnetic fusion devices.Comment: 4 pages, 5 figure
An Enhanced Nonlinear Critical Gradient for Electron Turbulent Transport due to Reversed Magnetic Shear
The first nonlinear gyrokinetic simulations of electron internal transport
barriers (e-ITBs) in the National Spherical Torus Experiment show that reversed
magnetic shear can suppress thermal transport by increasing the nonlinear
critical gradient for electron-temperature-gradient-driven turbulence to three
times its linear critical value. An interesting feature of this turbulence is
nonlinearly driven off-midplane radial streamers. This work reinforces the
experimental observation that magnetic shear is likely an effective way of
triggering and sustaining e-ITBs in magnetic fusion devices.Comment: 4 pages, 5 figure
Is COVID-19 a sexually transmitted disease and how does the COVID-19 pandemic affect sexually transmitted diseases?
Teledermatology in the Nordic Countries – Can we practice high-quality, easy-accessible patient care in a safe and responsible way if we serve digitally?
The measurement of aircraft performance and stability and control after flight through natural icing conditions
The effects of airframe icing on the performance and stability and control of a twin-engine commuter-class aircraft were measured by the NASA Lewis Research Center. This work consisted of clear air tests with artificial ice shapes attached to the horizontal tail, and natural icing flight tests in measured icing clouds. The clear air tests employed static longitudinal flight test methods to determine degradation in stability margins for four simulated ice shapes. The natural icing flight tests employed a data acquisition system, which was provided under contract to NASA by Kohlman Systems Research Incorporated. This system used a performance modeling method and modified maximum likelihood estimation (MMLE) technique to determine aircraft performance degradation and stability and control. Flight test results with artificial ice shapes showed that longitudinal, stick-fixed, static margins are reduced on the order of 5 percent with flaps up. Natural icing tests with the KSR system corroborated these results and showed degradation in the elevator control derivatives on the order of 8 to 16 percent depending on wing flap configuration. Performance analyses showed the individual contributions of major airframe components to the overall degration in lift and drag
The COVID-19 pandemic and immunological phenomena:Risk assessment for patients on immunosuppressive and immunomodulating medication
Molecular and biochemical characterization of a new thermostable bacterial laccase from<i> Meiothermus ruber</i> DSM 1279
A new bacterial laccase gene (mrlac) fromMeiothermus ruberDSM 1279 was successfully overexpressed to produce a laccase (Mrlac) in soluble form inEscherichia coliduring simultaneous overexpression of a chaperone protein (GroEL/ES).</p
- …