Effects of Disorder on Electron Heating in Ultracold Plasmas

TL;DR

This paper investigates how ionic disorder influences electron heating in ultracold plasmas, showing that disorder causes significant temperature increases and that mitigation strategies like Rydberg blockade have moderate effectiveness.

Contribution

It quantifies the impact of ionic disorder on electron heating and evaluates the effectiveness of Rydberg blockade in reducing disorder-induced heating in ultracold plasmas.

Findings

Electron dynamics transition from ordered to disordered arrangements with about 30% effect.

Disorder-induced heating can be mitigated moderately by Rydberg blockade.

Two-step plasma formation can increase Coulomb coupling, but with limited efficiency.

Abstract

Starting from the beginning of their research in the early 2000's, the ultracold plasmas were considered as a promising tool to achieve considerable values of the Coulomb coupling parameter for electrons. Unfortunately, this was found to be precluded by a sharp spontaneous increase of temperature, which was often attributed to the so-called disorder-induced heating (DIH). It is the aim of the present paper to quantify the effect of spontaneous heating as function of the initial ionic disorder and, thereby, to estimate the efficiency of its mitigation, e.g., by the Rydberg blockade. As a result of the performed simulations, we found that the dynamics of electrons exhibited a well-expressed transition from the case of the quasi-regular arrangement of ions to the disordered one; the magnitude of the effect being about 30%. Thereby, we can conclude that the two-step formation of ultracold plasmas - involving the intermediate stage of the blockaded Rydberg gas - can really serve as a tool to increase the degree of Coulomb coupling, but the efficiency of this method is moderate.