The Simplest Double Slit: Interference and Entanglement in Double Photoionization of H2
D. Akoury,1,2
K. Kreidi,1
T. Jahnke,1
Th. Weber,1,2
A. Staudte,1
M. Schöffler,1
N. Neumann,1
J. Titze,1
L. Ph. H. Schmidt,1
A. Czasch,1
O. Jagutzki,1
R. A. Costa Fraga,1
R. E. Grisenti,1
R. Díez Muiño,3
N. A. Cherepkov,4
S. K. Semenov,4
P. Ranitovic,5
C. L. Cocke,5
T. Osipov,2
H. Adaniya,2
J. C. Thompson,6
M. H. Prior,2
A. Belkacem,2
A. L. Landers,6
H. Schmidt-Böcking,1
R. Dörner1*
The wave nature of particles is rarely observed, in part because of their very short de Broglie wavelengths in most situations. However, even with wavelengths close to the size of their surroundings, the particles couple to their environment (for example, by gravity, Coulomb interaction, or thermal radiation). These couplings shift the wave phases, often in an uncontrolled way, and the resulting decoherence, or loss of phase integrity, is thought to be a main cause of the transition from quantum to classical behavior. How much interaction is needed to induce this transition? Here we show that a photoelectron and two protons form a minimum particle/slit system and that a single additional electron constitutes a minimum environment. Interference fringes observed in the angular distribution of a single electron are lost through its Coulomb interaction with a second electron, though the correlated momenta of the entangled electron pair continue to exhibit quantum interference.
1 Institut für Kernphysik, University Frankfurt, Max von Laue Str 1, D-60438 Frankfurt, Germany.
2 Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
3 Centro de Física de Materiales and Donostia International Physics Center, 20018 San Sebastián, Spain.
4 State University of Aerospace Instrumentation, 190000 St. Petersburg, Russia.
5 Department of Physics, Kansas State University, Cardwell Hall, Manhattan, KS 66506, USA.
6 Department of Physics, Auburn University, Auburn, AL 36849, USA.
* To whom correspondence should be addressed. E-mail: doerner{at}atom.uni-frankfurt.de
