Eur. Phys. J. D 11, 323-326 (2000)
https://doi.org/10.1007/s100530070058

Restoring entanglement in atomic collisions: A gedanken experiment

Department of Physics, University of Bergen, Allégaten 55, 5007 Bergen, Norway

Received: 2 December 1999
Revised: 12 May 2000
Published online: 15 September 2000

Abstract

A new type of collision experiments is discussed, where observations of two successive collisions of the same pair of particles would be possible. When such technology is available, a surprising restoring of entanglement, normally considered broken in usual collision experiments, could be observed. As an illustration the collision partners He⁺ and He⁺⁺ in a collision regime where the resonant charge transfer is dominating are considered. In the analysis it is shown that in such experiments, two spatially widely separated ion paths, corresponding in fact to two different charge states, would contribute coherently to the final amplitudes, describing which of the ions emerges as singly charged, i.e. which carries the single electron involved. The double collision experiments are not trivial, since their overall cross-sections are extremely small. Development of relevant experimental techniques will decide if the proposed phenomena remain in the field of gedanken experiments or enter the world of real experimental physics.