Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Excited state spatial distributions in a cold strontium gas

G. Lochead

Published Jan 1, 2012• 2 citations
OpenAlex

Abstract

This thesis describes the development of a new technique for measuring the spatial distribution of Rydberg atoms in a cold strontium gas. Strontium atoms are cooled and trapped in a magneto-optical trap and coherently excited to Rydberg states in a two-photon, three-level ladder scheme. Several methods of stabilizing the frequency to the cooling transition are discussed and characterized. A frequency stabilization scheme based on electromagnetically-induced transparency for the second laser required for Rydberg excitation is also explained. The Rydberg population dynamics are studied experimentally and modeled using an optical Bloch equation simulation. The divalent nature of strontium allows doubly excited “autoionizing” states to be accessed using resonant optical excitation. These states ionize in subnanosecond timescales, with the ions recorded on a micro-channel plate being proportional to the amount of Rydberg atoms. Translation of an autoionizing laser focused to a waist of 10 μm gives a spatially resolved Rydberg signal. A two-dimensional map of the Rydberg spatial distribution has been made using this autoionizing microscopy technique.

Related papers

First observations of Rydberg blockade in a frozen gas of divalent atoms

Danielle Boddy

This thesis details the first measurements of Rydberg dipole blockade in a cold ensemble of divalent atoms. Strontium atoms are cooled and trapped in a magneto-optical trap and coherently excited to Rydberg states in a two-photon, three-level ladder scheme. Owing to the divalent nature of strontium, one electron can be excited to the Rydberg state, whilst the other lower-lying electron is available to undergo resonant optical excitation to autoionising states, which ionise in sub-nanosecond timescales. The remaining ions that are recorded on a micro-channel plate are proportional to the number of Rydberg atoms. The development of a narrow linewidth laser system necessary for an additional stage of cooling is explained and characterised. Two frequency stabilisation schemes are discussed: one to address the short-term laser frequency instabilities based on the Pound-Drever-Hall technique; the other to address the long-term laser frequency instabilities based on Lamb-dip spectroscopy in an atomic beam. The cooling dynamics on the narrow cooling transition is studied experimentally and modelled via theoretical simulations.

•Jan 1, 2014•9 citations

Many-body interactions in a dissipative frozen strontium Rydberg gas

D. P. Sadler

This thesis describes an investigation of Rydberg excitation within a high-density sample of cold strontium atoms. This sample is prepared using a two-stage magneto-optical trap, cooling first on a broad singlet transition and then a narrow triplet transition. Rydberg atoms are then created using a two-photon, three-level ladder type scheme and detected using a novel autoionisation technique. It is shown that, in the regime of high optical thickness on the probing transition, a significant Rydberg population can be created by photons that are multiply scattered before leaving the cloud. The multiply scattered field is density-dependent and has strikingly different spectral properties from the incident laser light. This spectrum is convolved with the spectrum of the Rydberg atoms created via direct laser excitation and the two spectra can be isolated in post analysis. This technique provides a probe of the spectral distribution of the re-scattered light within the cloud, which may be qualitatively different from that of the transmitted light, and previously has not been measured directly. Additionally, this Rydberg population arising from the multiply scattered field can be seen in the spatial distribution of the Rydberg excitations within the atom sample. Finally, a careful analysis of the time dynamics of the Rydberg system reveals that multiple scattering co-exists with signatures of the Rydberg blockade in this strongly dissipative regime.

•Jan 1, 2016•2 citations

Rydberg spectroscopy and dressing in an ultracold strontium gas

Niamh Jackson

This thesis describes Rydberg spectroscopy and dressing experiments in an ultracold strontium gas. The strontium atoms are cooled to sub-uK temperatures in a narrowline magneto-optical trap, where Rydberg atoms are created using a two-photon excitation scheme. This required the development of a high-power ultraviolet laser system at 319 nm. The laser has a large tuning range for access to triplet Rydberg states from principal quantum numbers of 35 to > 300. By performing Rydberg spectroscopy in a magneto-optical trap, we show that narrow spectra can be obtained where the line centre is determined to ~ 10 kHz. A frequency comb is then employed to make absolute frequency measurements of optical transitions to accuracies of < 2 MHz. Techniques are outlined for improving the accuracy further, showing that overall uncertainties on the order of 10 kHz can be obtained. The reliable measurement of Rydberg levels is important for studying the variation in quantum defect across Rydberg series, and hence improving the accuracy of atomic models. In this work we also develop a novel system in which to realise Rydberg dressing. By resonantly coupling the excited state of the cooling transition to a high lying Rydberg state, we create a Rydberg-dressed magneto-optical trap. We demonstrate that the atoms acquire Rydberg properties, while undergoing continuous cooling at ~ 1 uK. The lifetime of the trap is proved to be sufficiently long to observe interactions, however the interaction strength is currently limited by the non-uniform spatial profile of the dressing beam. Straightforward methods to overcome this limitation are presented. As such this work should lead to future experiments, whereby tuneable long-range interactions can be observed in the dynamics of the dressed magneto-optical trap.

•Jan 1, 2018•0 citations

Spectroscopy of a cold strontium Rydberg gas

James Millen, G. Lochead, G R Corbett +2 more

We present a study of a cold strontium Rydberg gas. The narrowband laser excitation of Rydberg states in the range n = 20–80 from a 6 mK cloud of strontium atoms is detected using the spontaneous ionization of the Rydberg atoms. Using a high-resolution step-scanning technique, we perform detailed measurements of the Stark maps of selected Rydberg states. We find excellent agreement between the measured Stark maps and a numerical calculation based on an independent electron model. Finally we show that excitation of the second valence electron can be used to probe the dynamics of the Rydberg gas with nanosecond temporal resolution via autoionization.

arXiv:1102.2715•Journal of Physics B Atomic Molecular and Optical Physics•Sep 14, 2011•34 citations

A cold strontium Rydberg gas

James Millen

Cold gases of Rydberg atoms are an ideal system in which to study the novel effects of strong interatomic interactions. This thesis describes the design and construction of the world's first experiment to study Rydberg states in a cold gas of an alkaline earth metal, in this particular case strontium. We have studied a wide range of Rydberg states, and have developed a sensitive ``step-scan" spectroscopic technique that detects the spontaneous ionization of the Rydberg gas. The step-scan method is used to acquire Stark maps, and these measurements verify a single-electron model for calculating dipole matrix-elements. From the matrix-elements, interaction strengths between strontium Rydberg atoms have been calculated for the first time. The presence of two valence electrons in an alkaline earth metal, such as strontium, offers a new angle on the study of Rydberg atoms. We create doubly excited ``autoionizing" states, the first such study in a cold gas. Autoionization is used as a high yield probe of Rydberg states, and enables a study of excitation dynamics with nanosecond time-resolution. We show that autoionization can quantitatively identify and elucidate state mixing in the Rydberg gas, and probe population transfer at the very onset of ultra-cold plasma formation.

•Jan 1, 2011•6 citations

Coherent Excitation of Rydberg States in the Gas of Cold 40Ca Atoms

Boris B. Zelener, I. D. Arshinova, A. A. Bobrov +5 more

The spectra of highly excited 40 Ca atoms prepared using a magneto-optical trap and an ultraviolet laser are experimentally studied. The dependence of the atomic density in the magneto-optical trap on the detuning frequency of cooling radiation and on the magnetic field gradient is determined. By using the technique based on the reduction of resonance fluorescence, the energy of the 76 1 S 0 Rydberg state for 40 Ca atoms is determined. A new scheme for stabilization of the laser frequency to create highly excited Rydberg atoms is demonstrated. This scheme employs the saturated absorption spectrum in a cell with rubidium atomic gas.

Journal of Experimental and Theoretical Physics Letters•Dec 1, 2018•7 citations
This thesis describes the development of a new technique for measuring the spatial distribution of Rydberg atoms in a cold strontium gas. Strontium atoms are cooled and trapped in a magneto-optical trap and coherently excited to Rydberg states in a two-photon, three-level ladder scheme. Several methods of stabilizing the frequency to the cooling transition are discussed and characterized. A frequency stabilization scheme based on electromagnetically-induced transparency for the second laser required for Rydberg excitation is also explained. The Rydberg population dynamics are studied experimentally and modeled using an optical Bloch equation simulation. The divalent nature of strontium allows doubly excited “autoionizing” states to be accessed using resonant optical excitation. These states ionize in subnanosecond timescales, with the ions recorded on a micro-channel plate being proportional to the amount of Rydberg atoms. Translation of an autoionizing laser focused to a waist of 10 μm gives a spatially resolved Rydberg signal. A two-dimensional map of the Rydberg spatial distribution has been made using this autoionizing microscopy technique.
This thesis details the first measurements of Rydberg dipole blockade in a cold ensemble of divalent atoms. Strontium atoms are cooled and trapped in a magneto-optical trap and coherently excited to Rydberg states in a two-photon, three-level ladder scheme. Owing to the divalent nature of strontium, one electron can be excited to the Rydberg state, whilst the other lower-lying electron is available to undergo resonant optical excitation to autoionising states, which ionise in sub-nanosecond timescales. The remaining ions that are recorded on a micro-channel plate are proportional to the number of Rydberg atoms. The development of a narrow linewidth laser system necessary for an additional stage of cooling is explained and characterised. Two frequency stabilisation schemes are discussed: one to address the short-term laser frequency instabilities based on the Pound-Drever-Hall technique; the other to address the long-term laser frequency instabilities based on Lamb-dip spectroscopy in an atomic beam. The cooling dynamics on the narrow cooling transition is studied experimentally and modelled via theoretical simulations.
This thesis describes an investigation of Rydberg excitation within a high-density sample of cold strontium atoms. This sample is prepared using a two-stage magneto-optical trap, cooling first on a broad singlet transition and then a narrow triplet transition. Rydberg atoms are then created using a two-photon, three-level ladder type scheme and detected using a novel autoionisation technique. It is shown that, in the regime of high optical thickness on the probing transition, a significant Rydberg population can be created by photons that are multiply scattered before leaving the cloud. The multiply scattered field is density-dependent and has strikingly different spectral properties from the incident laser light. This spectrum is convolved with the spectrum of the Rydberg atoms created via direct laser excitation and the two spectra can be isolated in post analysis. This technique provides a probe of the spectral distribution of the re-scattered light within the cloud, which may be qualitatively different from that of the transmitted light, and previously has not been measured directly. Additionally, this Rydberg population arising from the multiply scattered field can be seen in the spatial distribution of the Rydberg excitations within the atom sample. Finally, a careful analysis of the time dynamics of the Rydberg system reveals that multiple scattering co-exists with signatures of the Rydberg blockade in this strongly dissipative regime.
This thesis describes Rydberg spectroscopy and dressing experiments in an ultracold strontium gas. The strontium atoms are cooled to sub-uK temperatures in a narrowline magneto-optical trap, where Rydberg atoms are created using a two-photon excitation scheme. This required the development of a high-power ultraviolet laser system at 319 nm. The laser has a large tuning range for access to triplet Rydberg states from principal quantum numbers of 35 to > 300. By performing Rydberg spectroscopy in a magneto-optical trap, we show that narrow spectra can be obtained where the line centre is determined to ~ 10 kHz. A frequency comb is then employed to make absolute frequency measurements of optical transitions to accuracies of < 2 MHz. Techniques are outlined for improving the accuracy further, showing that overall uncertainties on the order of 10 kHz can be obtained. The reliable measurement of Rydberg levels is important for studying the variation in quantum defect across Rydberg series, and hence improving the accuracy of atomic models. In this work we also develop a novel system in which to realise Rydberg dressing. By resonantly coupling the excited state of the cooling transition to a high lying Rydberg state, we create a Rydberg-dressed magneto-optical trap. We demonstrate that the atoms acquire Rydberg properties, while undergoing continuous cooling at ~ 1 uK. The lifetime of the trap is proved to be sufficiently long to observe interactions, however the interaction strength is currently limited by the non-uniform spatial profile of the dressing beam. Straightforward methods to overcome this limitation are presented. As such this work should lead to future experiments, whereby tuneable long-range interactions can be observed in the dynamics of the dressed magneto-optical trap.
We present a study of a cold strontium Rydberg gas. The narrowband laser excitation of Rydberg states in the range n = 20–80 from a 6 mK cloud of strontium atoms is detected using the spontaneous ionization of the Rydberg atoms. Using a high-resolution step-scanning technique, we perform detailed measurements of the Stark maps of selected Rydberg states. We find excellent agreement between the measured Stark maps and a numerical calculation based on an independent electron model. Finally we show that excitation of the second valence electron can be used to probe the dynamics of the Rydberg gas with nanosecond temporal resolution via autoionization.
Cold gases of Rydberg atoms are an ideal system in which to study the novel effects of strong interatomic interactions. This thesis describes the design and construction of the world's first experiment to study Rydberg states in a cold gas of an alkaline earth metal, in this particular case strontium. We have studied a wide range of Rydberg states, and have developed a sensitive ``step-scan" spectroscopic technique that detects the spontaneous ionization of the Rydberg gas. The step-scan method is used to acquire Stark maps, and these measurements verify a single-electron model for calculating dipole matrix-elements. From the matrix-elements, interaction strengths between strontium Rydberg atoms have been calculated for the first time. The presence of two valence electrons in an alkaline earth metal, such as strontium, offers a new angle on the study of Rydberg atoms. We create doubly excited ``autoionizing" states, the first such study in a cold gas. Autoionization is used as a high yield probe of Rydberg states, and enables a study of excitation dynamics with nanosecond time-resolution. We show that autoionization can quantitatively identify and elucidate state mixing in the Rydberg gas, and probe population transfer at the very onset of ultra-cold plasma formation.
The spectra of highly excited 40 Ca atoms prepared using a magneto-optical trap and an ultraviolet laser are experimentally studied. The dependence of the atomic density in the magneto-optical trap on the detuning frequency of cooling radiation and on the magnetic field gradient is determined. By using the technique based on the reduction of resonance fluorescence, the energy of the 76 1 S 0 Rydberg state for 40 Ca atoms is determined. A new scheme for stabilization of the laser frequency to create highly excited Rydberg atoms is demonstrated. This scheme employs the saturated absorption spectrum in a cell with rubidium atomic gas.