Focus on the cold and ultracold chemistry of atoms, ions and molecules

Jesús Pérez‐Ríos

Impurity physics is a traditional topic in condensed matter physics that nowadays is being explored in the field of ultracold gases. Among the different classes of impurities, we focus on charged impurities in an ultracold bath. When a single ion is brought in contact with an ultracold gas, it is subjected to different reactive processes that can be understood from a cold chemistry perspective. In this work, we present an outlook of approaches for the dynamics of a single ion in a bath of ultracold atoms or molecules, complementing the usual many-body approaches characteristic of impurity physics within condensed matter physics. In particular, we focus on the evolution of a charged impurity in different baths, including external time-dependent trapping potentials, and explore the effect of the external laser sources present in ion-neutral hybrid traps on the reaction probability and evolution of an impurity.

Jesús Pérez‐Ríos

Jesús Pérez‐Ríos

A single ion in an ultracold gas is a versatile experimental platform to study interactions between charged and neutral particles in a controllable manner. When the gas density is large enough, a single ion can be viewed as an impurity in a sea of ultracold atoms or molecules. On the other hand, that single ion can also undergo a chemical reaction with atoms or molecules in the gas. This article discusses the dynamics of a charged impurity in an ultracold bath and the interplay between cold chemistry and impurity physics.

Takamasa Momose, Elena Savchenko

E. A. Hinds, B. E. Sauer, J. J. Hudson +2 more

Jesús Pérez‐Ríos, Maxence Lepers, Romain Véxiau +2 more

The dynamics of ultracold quantum gases composed of atoms or molecules with extremely low translational energy E t /k B << 1 millikelvin is dominated by the long-range mutual interactions between particles. Such studies require a detailed modelling of the atom-molecule or molecule-molecule long-range interactions inside the quantum gas with or without the presence of external fields. This paper focuses on two particular aspects relevant to ultracold chemistry: (i) The calculation of rates for photoassociation of a cold atom and a cold molecule to create ultracold excited trimers, based on the knowledge of the long-range interaction between the two species, showing that such rates are encouraging under the density and temperature conditions of a nearly degenerate quantum gas; (ii) The determination of the long-range interactions between two identical polar bialkali molecules in their rovibronic ground level in the presence of an electric field, showing the possibility for the formation of ultracold polar tetramers by stimulated emission.