The Simplest Double Slit: Interference and Entanglement in Double Photoionization of H ₂

Abstract

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.

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Affiliated Institutions

• Goethe University Frankfurt DE
• Saint Petersburg State University of Aerospace and Instrumentation RU
• Donostia International Physics Center ES
• Material Physics Center ES
• Lawrence Berkeley National Laboratory US
• Kansas State University US

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