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Laser Cooling and Atomic Physics

    PAST:   None
    PRESENT: Ongoing Research
    FUTURE: BECEDM-XPARCS RACE SALSMW-G

Launch Date: Late 2004 or 2005
Mission Duration: One year
Principle Investigator: Prof. Mark Kasevich, Yale University

 

SMW-G image

Gyroscopes have been used for over 150 years for a number of purposes. An important contribution by gyroscopes is in the area of navigation, because they are able to remain in a stable orientation. On ships, for example, they continued to point north, while the ship carrying them continually changed direction. This made them more reliable than magnetic compasses that were used to navigate for hundreds of years. In space applications, gyroscopes are also used for precision guidance as well as tests of fundamental physics

Currently, two practical gyros exist:

  • Mechanical gyroscopes - with a mechanical spinning body
  • Optical gyroscopes - a fiber gyro and laser gyro, based on laser interferometry

Currently under development are:

  • Atomic gyroscopes - that use wave property of matters, interferometry.
  • Superfliud gyroscopes - using cryogenic liquid helium, interferometry

The Interferometric gyro is based on the Sagnac effect, which is proportional to the energy of the interfering particles. Compared to a similar optical gyro, an atomic gyroscope would have 10 billion times higher sensitivity. This atomic gyro technology is being developed to support future space missions. The new capability would be particularly helpful in deep space automated navigation, in precision guidance such as telescope pointing and in observations of fundamental physics tests.

The atomic gyroscope relies on the peculiar quantum-mechanical wave property of all matters. Otherwise it works in principle the same way as optical gyroscopes. Atomic waveguides (that correspond to fiber in optics) will be developed to confine the atom wave and form the necessary interferometric loop. When they are working, atomic gyros send laser-cooled atoms along these atom wave-guides in the loop. This beam of atoms is split into two arms of a loop and recombined. A detectable shift in the distance around the sides of the loop results if there is the slightest rotation of the atomic gyroscope.

An interesting part of this concept to explain is that the waveguide splits individual atom wave packets into two pieces, which travel two paths at the same time. In other words, part of the atom is traveling one direction around the loop while the other part of the same atom goes the other way around the loop. One atom is, essentially, in two places at once. This is the essence of particle-wave duality in quantum mechanics.



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