Entanglement and Entropy in Electron-Electron Scattering

Abstract

Treating Coulomb scattering of two free electrons in a stationary approach, we explore the momentum and spin entanglement created by the interaction. We show that a particular discretisation provides an estimate of the von Neumann entropy of the one-electron reduced density matrix from the experimentally accessible Shannon entropy. For spinless distinguishable electrons the entropy is sizeable at low energies, indicating strong momentum entanglement, and drops to almost zero at energies of the order of 10 keV when the azimutal degree of freedom is integrated out, i.e. practically no entanglement and almost pure one-electron states. If spin is taken into account, the entropy for electrons with antiparallel spins should be larger than in the parallel-spin case, since it embodies both momentum and spin entanglement. Surprisingly, this difference, as well as the deviation from the spin-less case, is extremely small for the complete scattering state. Strong spin entanglement can however be obtained by post-selecting states at scattering angle pi/2.

References in corpus (6)

• Quantum entanglement
• Quantum Coherence as a Resource
• The Einstein-Podolsky-Rosen paradox: from concepts to applications
• Quantum Correlations in Two-Fermion Systems
• General criterion for the entanglement of two indistinguishable particles
• Generation of bipartite spin entanglement via spin-independent scattering

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• Entanglement in Elastic Electron Scattering: Perturbation theory misses fundamental aspects of Bragg scattering
• Two-electron quantum walks can probe entanglement and decoherence in an electron microscope