28,193 research outputs found
Periodically-driven quantum systems: Effective Hamiltonians and engineered gauge fields
Driving a quantum system periodically in time can profoundly alter its
long-time dynamics and trigger topological order. Such schemes are particularly
promising for generating non-trivial energy bands and gauge structures in
quantum-matter systems. Here, we develop a general formalism that captures the
essential features ruling the dynamics: the effective Hamiltonian, but also the
effects related to the initial phase of the modulation and the micro-motion.
This framework allows for the identification of driving schemes, based on
general N-step modulations, which lead to configurations relevant for quantum
simulation. In particular, we explore methods to generate synthetic spin-orbit
couplings and magnetic fields in cold-atom setups.Comment: 25 pages, 6 figures, includes Appendices (A-K). An erroneous factor
of two has been corrected in the last term of Eq. C10 (Appendix C); this typo
had no impact on the rest of the articl
Three-component laser anemometer measurement systems
A brief overview of the different laser anemometer (LA) optical designs available is presented. Then, the LA techniques that can be used to design a three-component measurement system for annular geometries are described. Some of the facility design considerations unique to these LA systems are also addressed. Following this, the facilities and the LA systems that were used to successfully measure the three components of velocity in the blading of annular-flow machines are reviewed. Finally, possible LA system enhancements and future research directions are presented
Analytical investigation of supersonic turbomachinery blading. 2 - Analysis of impulse turbine-blade sections
Surface Mach numbers, inlet flow angle, and specific heat ratio effects on geometric features of supersonic impulse turbine blade sections in Mach range 1.5 to 5.
Analytical investigation of blade efficiency for two-dimensional supersonic turbine rotor blade sections
Blade efficiency in producing vortex flow within two dimensional supersonic rotor blade section
Feasibility of multi-satellite occultation /refraction/ measurements for meteorology Final report
Radio refraction and occultation techniques for atmospheric density measurements between multiple satellite
Color Magnetic Corrections to Quark Model Valence Distributions
We calculate order color magnetic corrections to the valence quark
distributions of the proton using the Los Alamos Model Potential wavefunctions.
The spin-spin interaction breaks the model SU(4) symmetry, providing a natural
mechanism for the difference between the up and down distributions. For a value
of sufficient to produce the mass splitting, we find up
and down quark distributions in reasonable agreement with experiment.Comment: 25 Pages, LA-UR-93-132
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