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Results for “laser cooling atomic clock frequency standard laser-cooled”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS2001

Phase modulation for reduced vibration sensitivity in laser-cooled clocks in space

The standard interrogation technique in atomic beam clocks is square-wave frequency modulation (SWFM), which suffers a first order sensitivity to vibrations as changes in the transit time of the atoms translates to perceived frequency errors. Square-wave phase modulation (SWPM) interrogation eliminates sensitivity to this noise.

frequency standard frequency modulation phase modu↗
NASA NTRS2002

Design concept for the microwave interrogation structure in PARCS

In this paper we will describe key aspects of the conceptual design of the microwave interrogation structure in the laser-cooled cesium frequency standard that is part of the Primary Atomic Reference Clock in Space (PARCS) experiment.

frequency standard phase shift microwave cavity↗
NASA NTRS2001

Ground-Based Investigations with the Cryogenic Hydrogen Maser

The room temperature hydrogen maser is an active atomic oscillator used as a high-frequency-stability local oscillator for radio astronomy, metrology, and spacecraft navigation, and in tests of fundamental physics. The cryogenic hydrogen maser (CHM) operates at 0.5 K, employing superfluid helium-coated walls to store the masing hydrogen atoms. We are investigating whether the CHM may provide better frequency stability than the room temperature hydrogen maser: one to three orders of magnitude improvement may be possible because of greatly reduced thermal noise and larger signal power. Exceptional frequency stability will be required for spacecraft tracking in future deep-space missions, for space-based tests of relativity and gravitation, and for local (i.e., flywheel) oscillators used with absolute frequency standards such as laser-cooled atomic fountains and linear ion traps. These new devices are passive high-resolution frequency discriminators. Alone, they cannot function as superior atomic clocks; their effective operation depends on being integrated with an active local oscillator with excellent short term stability - such as that possible with the CHM.

Walsworth, Ronald L.↗
NASA NTRS2004

Laboratory Apparatus Generates Dual-Species Cold Atomic Beam

A laser cooling apparatus that generates a cold beam of rubidium and cesium atoms at low pressure has been constructed as one of several intermediate products of a continuing program of research on laser cooling and atomic physics. Laser-cooled atomic beams, which can have temperatures as low as a microkelvin, have been used in diverse applications that include measurements of fundamental constants, atomic clocks that realize the international standard unit of time, atom-wave interferometers, and experiments on Bose-Einstein condensation. The present apparatus is a prototype of one being evaluated for use in a proposed microgravitational experiment called the Quantum Interferometric Test of Equivalence (QuITE). In this experiment, interferometric measurements of cesium and rubidium atoms in free fall would be part of a test of Einstein s equivalence principle. The present apparatus and its anticipated successors may also be useful in other experiments, in both microgravity and normal Earth gravity, in which there are requirements for dual-species atomic beams, low temperatures, and low pressures. The apparatus includes a pyramidal magneto-optical trap in which the illumination is provided by multiple lasers tuned to frequencies characteristic of the two atomic species. The inlet to the apparatus is located in a vacuum chamber that contains rubidium and cesium atoms at a low pressure; the beam leaving through the outlet of the apparatus is used to transfer the atoms to a higher-vacuum (lower-pressure) chamber in which measurements are performed. The pyramidal magneto-optical trap is designed so that the laser cooling forces in one direction are unbalanced, resulting in a continuous cold beam of atoms that leak out of the trap (see figure). The radiant intensity (number of atoms per unit time per unit solid angle) of the apparatus is the greatest of any other source of the same type reported to date. In addition, this is the first such apparatus capable of producing a slow, collimated beam that contains two atomic species at the same time.

Thompson, Robert↗