Enhancement of Entanglement via Incoherent Collisions

TL;DR

This paper demonstrates that, contrary to common belief, incoherent collisions can enhance quantum entanglement in a three-level EIT system by increasing collisional decay rates, which improve interference effects.

Contribution

It reveals that collisional decay can be used to enhance entanglement in atomic systems, challenging the notion that collisions are solely detrimental to quantum coherence.

Findings

Entanglement between pump and probe fields increases with collisional decay rates.

Constructive interference is enhanced, while destructive interference is suppressed.

Results suggest collisions can be harnessed to improve quantum entanglement at high temperatures.

Abstract

In contrast to the general thought that the collisions are intrinsically dephasing in nature and detrimental to quantum entanglement at room or higher temperatures, here, we show that in the conventional ladder-type three-level electromagnetically induced transparency (EIT) configuration, when the probe field intensity is not very weak as compared to the pump field, the entanglement between the bright pump and probe fields can be remarkably enhanced with the increase of the collisional decay rates in a moderate range in an inhomogeneously-broadened atomic system. The strengthened entanglement results from the enhancement of constructive interference and suppression of destructive interference between one-photon and multi-photon transition pathways. Our results clearly indicate that the collisions offer a promising alternative to enhance entanglement at room or higher temperatures despite of the dephasing nature, which provides great convenience for experimental implementation, and opens new prospects and applications in realistic quantum computation and quantum information processing.