9 research outputs found
An experimental and theoretical guide to strongly interacting Rydberg gases
We review experimental and theoretical tools to excite, study and understand
strongly interacting Rydberg gases. The focus lies on the excitation of dense
ultracold atomic samples close to, or within quantum degeneracy, to high lying
Rydberg states. The major part is dedicated to highly excited S-states of
Rubidium, which feature an isotropic van-der-Waals potential. Nevertheless, the
setup and the methods presented are also applicable to other atomic species
used in the field of laser cooling and atom trapping.Comment: 23 pages, 22 figures, tutoria
Coupling a single electron to a Bose-Einstein condensate
The coupling of electrons to matter is at the heart of our understanding of
material properties such as electrical conductivity. One of the most intriguing
effects is that electron-phonon coupling can lead to the formation of a Cooper
pair out of two repelling electrons, the basis for BCS superconductivity. Here
we study the interaction of a single localized electron with a Bose-Einstein
condensate (BEC) and show that it can excite phonons and eventually set the
whole condensate into a collective oscillation. We find that the coupling is
surprisingly strong as compared to ionic impurities due to the more favorable
mass ratio. The electron is held in place by a single charged ionic core
forming a Rydberg bound state. This Rydberg electron is described by a
wavefunction extending to a size comparable to the dimensions of the BEC,
namely up to 8 micrometers. In such a state, corresponding to a principal
quantum number of n=202, the Rydberg electron is interacting with several tens
of thousands of condensed atoms contained within its orbit. We observe
surprisingly long lifetimes and finite size effects due to the electron
exploring the wings of the BEC. Based on our results we anticipate future
experiments on electron wavefunction imaging, investigation of phonon mediated
coupling of single electrons, and applications in quantum optics.Comment: 4 pages, 3 figures and supplementary informatio
Lifetimes of ultralong-range Rydberg molecules in vibrational ground and excited state
Since their first experimental observation, ultralong-range Rydberg molecules
consisting of a highly excited Rydberg atom and a ground state atom have
attracted the interest in the field of ultracold chemistry. Especially the
intriguing properties like size, polarizability and type of binding they
inherit from the Rydberg atom are of interest. An open question in the field is
the reduced lifetime of the molecules compared to the corresponding atomic
Rydberg states. In this letter we present an experimental study on the
lifetimes of the ^3\Sigma (5s-35s) molecule in its vibrational ground state and
in an excited state. We show that the lifetimes depends on the density of
ground state atoms and that this can be described in the frame of a classical
scattering between the molecules and ground state atoms. We also find that the
excited molecular state has an even more reduced lifetime compared to the
ground state which can be attributed to an inward penetration of the bound
atomic pair due to imperfect quantum reflection that takes place in the special
shape of the molecular potential