Falling atoms measure the Earth’s rotation

A new type of gyroscope based on interfering atoms has been developed that can determine the latitude where the instrument is located – and also measure true north and the Earth’s rate of rotation. The device has been developed by physicists in the US, who hope to scale it up so that it can test Einstein’s general theory of relativity. They also want to miniaturize the technology so it can be used in portable navigation systems.

The gyroscope has been built by a team led by Mark Kasevich at Stanford University in California. It works by firing a cloud of atoms upwards at a slight angle to the vertical so that the atoms follow a parabolic trajectory as gravity pulls them down. A series of laser pulses is then fired at the cloud while in flight, which separates the atoms into a number of different bunches that follow different trajectories. The pulses are carefully selected so that two of these trajectories cross paths at a detector.

Given that the atoms are governed by quantum mechanics, they behave like waves with a relative shift in phase between the atoms taking different paths. The resulting interference at the detector is dictated in part by the relative orientations of the laser pulses, gravity and the rotation of the Earth.

via Falling atoms measure the Earth’s rotation

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