Atominterferometer

An atom interferometer is an interferometer that utilizes the wave properties of atoms. With interferometers fundamental constants like the gravitational constant with high accuracy can be determined, but may also phenomena such as gravitational waves are investigated.

Overview

Interferometry based on wave properties. As postulated by Louis de Broglie in his thesis, to particles, including atoms behave like waves (so-called wave -particle duality ) can - this is a key principle of quantum mechanics. If in experiments a very high accuracy is required, increasingly atom interferometers are used, because atoms have a very small de Broglie wavelength. Some experiments use now even molecules to achieve even smaller wavelengths and to search for the limits of the validity of quantum mechanics. In many experiments with atoms of the roles of matter and light compared to laser -based interferometers are swapped; the beam splitters and mirrors are laser, however, the source emits matter waves (the atoms).

Interferometers

The use of atoms allows higher frequencies (and hence accuracy ) to be used as in the light, but at the same time are also more exposed to atoms of gravity. In some devices, the atoms are ejected upwards and the interferometry is performed while the atoms in flight or in free fall. In other experiments, additional forces are applied to the gravitational forces to compensate. These guided systems allow in principle unlimited long measurement times, their coherence is still discussed. Recent theoretical studies suggest that consistency is maintained in controlled systems, but this is yet to be confirmed experimentally.

The first atom interferometers used slots or wires as beam splitters and mirrors. Later systems, especially the guided light forces used for distribution and reflective of the matter wave.

History

The separation of matter waves complete atoms in 1929 for the first time observed by Estermann and Stern were bowed as hydrogen and helium beams on a surface of sodium chloride. The first modern atom interferometers were reported in 1991 a double-slit experiment with metastable helium to Young atoms and a microstructured double slit of Carnal and Mlynek and an interferometer with three micro-structured diffraction gratings and sodium atoms in the group to Pritchard at MIT. Shortly after it was found at the Physikalisch -Technische Bundesanstalt ( PTB) that an optical Ramsey spectrometer, which is commonly used in atomic clocks, can also be used as atom interferometers. The largest spatial separation between packages of partial waves was achieved by laser cooling and stimulated Raman transitions by Chu and co-workers at Stanford.