Monday, January 30, 2012

Neutron Phase and Gravity

In my research this morning, I came across a collection of interesting articles from the 1970s where researchers observed a shift in the phase of a neutron's quantum wave function because of a change in the gravitational potential. This is similar to the Aharanov-Bohm effect, but using a gravitational rather than an electromagnetic potential. If you're a university student like myself, all the journal links below should be accessible via your university's library.

The experiment design is described in
Experimental Test of Gravitationally Induced Quantum Interference

The results of the experiment are presented in:
Observation of Gravitationally Induced Quantum Interference

Another similar experiment by the same researchers was described in:
Observation of a Phase Shift of a Neutron Due to Precession in a Magnetic Field

For a nice primer of all things Aharanov-Bohm with reference to the above mentioned experiments, see Reviews of Modern Physics:
The quantum effects of electromagnetic fluxes

One of the experimenters, Overhauser, discusses the experiment and its relation to the Aharanov-Bohm effect at length in:
Coherence effects in neutron diffraction and gravity experiments
Greenberger D. & Overhauser A. (1979). Coherence effects in neutron diffraction and gravity experiments, Reviews of Modern Physics, 51 (1) 43-78. DOI: A

 review of the great things that can be done with a neutron interferometer including the experiments mentioned above can be found in Reviews of Modern Physics.
The neutron interferometer as a device for illustrating the strange behavior of quantum systems
Greenberger D. (1983). The neutron interferometer as a device for illustrating the strange behavior of quantum systems, Reviews of Modern Physics, 55 (4) 875-905. DOI:

The author, Greenberger, of the above-mentioned article thanks John Wheeler, Overhauser, Werner, and Herman Feshbach as well as other famous physicists.

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