Two electron entanglement enhancement by an inelastic scattering process

TL;DR

This paper demonstrates that inelastic scattering processes can enhance two-electron entanglement, challenging the common notion that inelastic effects degrade quantum coherence, by analyzing an exactly solvable two-particle scattering model.

Contribution

It introduces a generalized S matrix formalism for non-unitary evolution and shows how inelasticity can increase entanglement, providing new insights into quantum scattering processes.

Findings

Inelastic scattering can increase electron entanglement compared to elastic scattering.

Concurrence zeros are controlled by resonance energies or reflection conditions.

Exciting the scatterer cannot fully destroy phase coherence due to intrinsic inelastic limits.

Abstract

In order to assess inelastic effects on two fermion entanglement production, we address an exactly solvable two-particle scattering problem where the target is an excitable scatterer. Useful entanglement, as measured by the two particle concurrence, is obtained from post-selection of oppositely scattered particle states. The $S$ matrix formalism is generalized in order to address non-unitary evolution in the propagating channels. We find the striking result that inelasticity can actually increase concurrence as compared to the elastic case by increasing the uncertainty of the single particle subspace. Concurrence zeros are controlled by either single particle resonance energies or total reflection conditions that ascertain precisely one of the electron states. Concurrence minima also occur and are controlled by entangled resonance situations were the electron becomes entangled with the scatterer, and thus does not give up full information of its state. In this model, exciting the scatterer can never fully destroy phase coherence due to an intrinsic limit to the probability of inelastic events.