Many-Body Effects in a Frozen Rydberg Gas

Abstract

We studied the properties of a cold (ϳ100 mK) and dense (ϳ10 8 10 cm 23) atomic Rydberg Cs gas, and found that the observed widths and shapes of resonances in population transfers cannot be explained in the framework of a usual gas model. We propose a "frozen Rydberg gas" model, where the interplay between two-body and many-body phenomena affects in an unexpected way the width and the shape of spectral lines. [S0031-9007(97)04903-X]

Ultra-cold ion–atom collisions: near resonant charge exchange

“…Two decades ago, in studies of atomic ions embedded in liquid helium, the measurement of ion mobilities helped to elucidate the microscopic structure of quantum liquids and served as a valuable probe of their properties. Recent experiments have been directed to observing ultracold atomic systems in which electric charges may play an analogous role: these include ultracold plasmas [12], ultracold Rydberg gases [13,14] and direct ionization experiments in BEC [15,16]. Observations of atomic and molecular collision processes involving ions at low energies can also be performed using Coulomb crystals [17], where an array of trapped atomic ions or sympathetically cooled molecular ions [18] is used as a cold target buffer because of its spatial localization and the low translational temperatures of 10 mK.…”

Spectral linewidth broadening from pair fluctuations in a frozen Rydberg gas

“…spectral line broadening [1,2,3], number correlation [6,12,13] and collective excitation [8]. Many experimental results can be understood from the well-known dipole blockade effect: when two Rydberg atoms are close enough, the dipolar interaction will shift them out of resonance with the external driving laser, thus double excitation is greatly suppressed.In this paper, we are interested in the unusual line width broadening which was observed in experiments [1,2]. To be specific, we will consider the following two cases.…”

“…Ee,34.20.Cf Rydberg gases have attracted renewed interest in recent years due to the unprecedented advancement in laser cooling and trapping [1,2,3,4,5,6,7,8,9]. Rydberg atoms, possessing a large dipole moment and long lifetime, can interact with each other coherently for relatively long times, which make it a potential candidate for quantum information processing [10,11].…”

“…[1], the band formed by the diffusion of |ss ′ is coupled to the state |ss ′ and the existence of this band broadens this population transfer [1,14], which shows that the broadening should be a result of the many-body effect. However, we believe that it is mostly a two-body effect arising from the density fluctuation, as we will show below by simple theoretical reasoning and numerical simulations.…”

“…In this paper, we are interested in the unusual line width broadening which was observed in experiments [1,2]. To be specific, we will consider the following two cases.…”