National Institute of Standards and Technology

About: National Institute of Standards and Technology is a government organization based out in Gaithersburg, Maryland, United States. It is known for research contribution in the topics: Laser & Scattering. The organization has 26667 authors who have published 60661 publications receiving 2215547 citations. The organization is also known as: National Bureau of Standards & NIST.

Dynamics of component separation in a binary mixture of Bose-Einstein condensates

Abstract: We describe the first experiments that study in a controlled way the dynamics of distinguishable and interpenetrating bosonic quantum fluids. We work with a two-component system of Bose-Einstein condensates in the $|{F\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1,m}_{f}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}1〉$ and $|2,1〉$ spin states of ${}^{87}\mathrm{Rb}$. The two condensates are created with complete spatial overlap, and in subsequent evolution they undergo complex relative motions that tend to preserve the total density profile. The motions quickly damp out, leaving the condensates in a steady state with a non-negligible (and adjustable) overlap region.

Experiments and theory in cold and ultracold collisions

Abstract: The authors review progress in understanding the nature of atomic collisions occurring at temperatures ranging from the millidegrees Kelvin to the nanodegrees Kelvin regime. The review includes advances in experiments with atom beams, light traps, and purely magnetic traps. Semiclassical and fully quantal theories are described and their appropriate applicability assessed. The review divides the subject into two principal categories: collisions in the presence of one or more light fields and ground-state collisions in the dark.

Rapid and precise absolute distance measurements at long range

Abstract: The ability to determine absolute distance to an object is one of the most basic measurements of remote sensing. High-precision ranging has important applications in both large-scale manufacturing and in future tight formation-flying satellite missions, where rapid and precise measurements of absolute distance are critical for maintaining the relative pointing and position of the individual satellites. Using two coherent broadband fibre-laser frequency comb sources, we demonstrate a coherent laser ranging system that combines the advantages of time-of-flight and interferometric approaches to provide absolute distance measurements, simultaneously from multiple reflectors, and at low power. The pulse time-of-flight yields a precision of 3 µm with an ambiguity range of 1.5 m in 200 µs. Through the optical carrier phase, the precision is improved to better than 5 nm at 60 ms, and through the radio-frequency phase the ambiguity range is extended to 30 km, potentially providing 2 parts in 1013 ranging at long distances. Using two coherent broadband fibre-laser frequency comb sources, a coherent laser ranging system for absolute distance measurements is demonstrated. Its combination of precision, speed and long range may prove particularly useful for space-based sciences.

Thermal noise in mechanical experiments

Abstract: The fluctuation-dissipation theorem is applied to the case of low-dissipation mechanical oscillators, whose losses are dominated by processes occurring inside the material of which the oscillators are made. In the common case of losses described by a complex spring constant with a constant imaginary part, the thermal noise displacement power spectrum is steeper by one power of $\ensuremath{\omega}$ than is predicted by a velocity-damping model. I construct models for the thermal noise spectra of systems with more than one mode of vibration, and evaluate a model of a specific design of pendulum suspension for the test masses in a gravitational-wave interferometer.