Atom interferometer
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| Contents |
Overview
Interferometry inherently depends on the wave nature of the object. As pointed out by de Broglie in his PhD-thesis, particles, including atoms, can behave like waves (the so called Wave-particle duality, according to the general framework of quantum mechanics). More and more high precision experiments now deploy atom interferometers due to their short de Broglie wavelength. Some experiments are now even deploying molecules to obtain even shorter de Broglie wavelengths and to search for the limits of quantum mechanics. In many experiments with atoms, the roles of matter and light are reversed compared to the laser based interferometers, i.e., the beam splitter and mirrors are lasers while the source emits rather matter waves (the atoms).
Interferometer types
Contrary to light, atoms are subject to gravity. In some apparatus, the atoms are ejected upwards and the interferometry takes place while the atoms are in flight, sometimes they are measured while falling in free flight. Yet other experiments do not negate gravitational effects by free accleration, but use additional forces to compensate for gravity. While these guided systems in principle can provide arbitrary amounts of measurement time, their quantum coherence is still under discussion. Recent theoretical studies indicate however, that coherence is indeed preserved in the guided systems, but this has yet to be experimentally confirmed.
The early atom interferometers deployed slits or wires for the beam splitters and mirrors. Later systems, especially the guided ones, used light forces for splitting and refelcting of the matter wave.
Examples
| Group | Year | Atomic Species | Method | Measured effect(s) |
|---|---|---|---|---|
| Schmiedmayer | Na, Na2 | Nano-fabricated gratings | Stark phase shift | |
| Zeilinger | Ar | Classical fringes behind three gratings | Gravity: Sagnac: 
| |
| Sterr | Ramsey-Bordé | Polarizability, Aharanov-Effect: exp/theo  ,Sagnac 
| ||
| Kasevich | Doppler on falling atoms | Gravimeter:  Rotation:  ,fine structure constant 
| ||
| Berman | Talbot-Lau |
History
See also
- C. S. Adams and M. Sigel and J. Mlynek, Atom Optics. Phys. Rep. 240, 143 (1994). Overview of the atom-light interaction
- P. R. Berman [Editor], Atom Interferometry. Academic Press (1997). Detailed overview of atom interferometers at that time (good introductions and theory).
