Photon exchange and entanglement formation during the transmission through a rectangular quantum barrier

TL;DR

This paper analytically investigates photon exchange and entanglement formation when a quantum particle transmits through a rectangular quantum barrier created by a quantum field, revealing unique quantum effects and state-dependent entanglement characteristics.

Contribution

It provides explicit analytic transition amplitudes for photon exchange processes across various initial field states, highlighting novel entanglement and symmetry effects.

Findings

Entanglement links particle position to photon number in coherent states.

Distinct differences from classical fields in emission-absorption symmetry and resonance.

Unique behaviors when the field starts in vacuum state.

Abstract

When a quantum particle traverses a rectangular potential created by a quantum field both photon exchange and entanglement between particle and field take place. We present analytic results for the transition amplitudes of any possible photon exchange processes for an incoming plane wave and initial Fock, thermal and coherent field states. We show that for coherent field states the entanglement correlates the particle's position to the photon number in the field instead of the particle's energy as usual. Besides entanglement formation, remarkable differences to the classical field treatment also appear with respect to the symmetry between photon emission and absorption, resonance effects and if the field initially occupies the vacuum state.