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

Rydberg Molecules and Excitation of Lattice-Mixed Rydberg States in a Deep Ponderomotive Optical Lattice

Jamie MacLennan

Published Jan 1, 2021• 1 citation
Publisher

Abstract

In this dissertation, I explore several aspects of Rydberg physics with laser spectroscopy. The experiments center around the use of a very deep, cavity-generated, one-dimensional optical lattice in a cold atom sample. The optical lattice produces elongated clouds of dense, cold atoms via dipole trapping and is able to generate extreme light shifts in the atoms due to its high intensity. I describe experiments which may be divided into two main classes. In the first, I use the dipole trap to prepare a dense sample of atoms for photoassociation of Rb atom pairs into diatomic Rydberg molecules. The Rydberg molecules are formed by low-energy scattering of the Rydberg electron of one atom from the other atom, which is a ground-state atom. This novel binding mechanism also has relevance for chemical physics. I present binding energy measurements for eight different cases of Rydberg molecules. The binding energies reveal information about electron-atom collisions, such as their scattering lengths, and about the spin couplings present within the molecular system. In the second class of experiments, I introduce two proposed measurements in which the optical lattice is ramped to very high intensity during the laser excitation, creating AC Stark shifts in the transition frequencies. In one measurement, low-lying atomic states are probed. Measurements of the light shifts are expected to yield data on the dynamic polarizability and the photoionization cross section of the 5$D_{3/2}$-state in rubidium in a 1064-nm light field. I show corresponding preliminary experimental data. The polarizability and photo-ionization cross-section measurements will provide tests of atomic structure theory, which is important both at a fundamental level and for applications such as atomic clocks. In another proposed measurement, Rydberg atoms in the lattice experience ponderomotive shifts and strong mixing of their angular-momentum states, allowing direct optical excitation of the lattice-mixed high-angular-momentum states. I describe the theoretical basis and experimental preparation for spectroscopically characterizing the lattice-mixed states. The ability to optically excite selected high-angular-momentum states without the use of static or RF fields may be useful for quantum information processing and simulation.

DOI
10.7302/1551

Related papers

Rydberg Molecules and Circular Rydberg states in Cold Atom Clouds.

David Alexander Anderson

In this dissertation I investigate cold Rydberg atoms and molecules in which the angular-momentum character of the quantum states involved strongly influences their properties and dynamics. In the first part I focus on long-range diatomic Rydberg molecules formed by a rubidium D-state Rydberg atom and a second rubidium atom in its ground state. Spectroscopic measurements of molecular binding energies are presented showing the effect of the Rydberg atom size and fine-structure coupling on the molecular potentials. A theoretical model is introduced that takes into account all relevant angular-momentum couplings between the molecular constituents, successfully reproducing experimental observations. Calculations of adiabatic potentials and binding energies, molecular-state lifetimes, electric and magnetic dipole moments are also presented. In the second part, I describe the production and magnetic trapping of cold circular Rydberg atoms. The circular Rydberg atoms are generated out of a cold gas of rubidium using the crossed-fields method and magnetically trapped. The trapping force is employed to induce center-of-mass oscillations of the trapped atom sample. Trap parameters and observed oscillation frequencies are used to measure the magnetic moments of the circular Rydberg atoms. Trap losses and the atomic internal-state evolution in the 300 Kelvin thermal background are also investigated.

•Jan 1, 2015•0 citations

Precision Measurements and Quantum Sensing Using Cold Atoms

Alisher Duspayev

Atoms cooled and trapped using laser light have become the backbone of modern quantum physics research. Various new applications based on laser-cooled atoms are in active development. The work described in this dissertation is dedicated to this endeavor. I present experimental and numerical investigations on several fundamental properties of the laser-cooled atoms in different quantum states and how they may translate into applications within several emerging atom-based technologies. First, I describe the precision measurements of the dynamic polarizability and photo-ionization cross-section at 1064-nm light of the $5D_{3/2}$ state in rubidium, which is of interest for the portable atomic clocks. Two different spectroscopic methods are implemented to extract the polarizability from the experimental data. The results are statistically equivalent: -524(17) [-499(59)] atomic units from the first [second] method. The photo-ionization cross section of the $5D_{3/2}$ state at 1064~nm is measured to be 44(1) Mb. The aforementioned photo-ionization cross section is suitable for efficient ion generation and the subsequent application in cold-atom-based ion sources. This is demonstrated in the second study presented here. The ion source employs a novel method to monitor the electric microfields of the ions using the Stark effect of the highly-excited (Rydberg) atoms seeded within the origin of the ion source. Rydberg atoms are extremely sensitive to electric fields and serve as an embedded real-time sensor and tracker of the ion-source performance because of their quasicontinuous creation and detection. The principles of such ion-microfield sensing are discussed and analyzed in detail and can be utilized in any cold-atom-based focused-ion-beam source. The hyperfine structure of the $4D_{3/2}$ state in rubidium is investigated next. The measurement utilizes two-photon optical absorption spectroscopy and a detailed analysis of light shifts. All four hyperfine components are resolved in the experimental data. The magnetic-dipole and electric-quadrupole hyperfine constants are obtained to be 7.419(45) MHz and 4.19(19) MHz, respectively. Future applications of the $4D_{3/2}$ state in optical atomic clocks and Rydberg-atom physics are discussed. Next, I investigate a Rydberg-atom-ion molecule bound by long-range multipolar forces. The molecule is the first example of a bound state between a Rydberg atom and an ion. Strong interactions between these two particles lead to large molecular binding energy (reaching a few GHz) and large binding length (exceeding 1 $mu$m). The Born-Oppenheimer approximation does not hold for the Rydberg-atom-ion molecule because the motion of the Rydberg-atom nucleus is on the same timescale as the dynamics of the ion. The Born-Huang theory is utilized to investigate the resultant nonadiabatic dynamics of the molecule and to make the first fully quantum predictions of its lifetime as a function of the vibrational state and quantum principal number of the Rydberg atom. Lastly, I present a novel technique for atom interferometry that employs uninterrupted three-dimensional confinement and manipulation during the interferometric protocol. The atoms in the existing apparatuses have to follow several-meter-long trajectories along which various detrimental effects such as wave-packet dispersion erase useful phase information. ``Tractor atom interferometry" presented here promises to suppress the harmful effects and improve the interferometers’ sensitivity; provide flexible control over the atomic trajectories; and significantly reduce the experimental footprint. The suitability of this approach for measuring background acceleration (such as due to the gravitational field) is demonstrated. The sensitivity estimations, experimental considerations, and initial laboratory work are discussed.

•Jan 1, 2024•0 citations

Deep and Periodically Driven Optical Lattices for Fundamental Physics

Ryan Cardman

Fundamental physics is concerned with the problems of defining fundamental constants, units of measurement, and searching for new forces and aspects of matter. Usually, the best way to resolve these inquiries is to have a precise knowledge of atomic energy levels and the transition frequencies in order for their quantum states to be manipulated. Spectroscopy is a tool that probes these atomic energy levels by observing the atom's response as the energy of the applied radiation is varied. Over the past century, spectroscopy using electromagnetic radiation has involved direct interactions with the atom's electric and magnetic multipole moments via the $textbf{A}cdottextbf{p}$ term of the minimal coupling Hamiltonian. The work presented in this thesis utilizes such interactions with laser fields and goes a step further by exploring a novel light-matter interaction via the $A^2$ term. Leading problems in the field of fundamental physics include the commercialization of optical frequency standards with short-term stabilities beating $10^{-11}/sqrt{tau}$ and the discovery of new science arising from competitive precision measurements of the Rydberg constant and the detection of axion dark matter. Ultracold rubidium atoms subject to periodic optical potentials in standing waves of light known as optical lattices offer solutions to these problems. Rubidium atoms contained in miniaturized, glass vapor cells can be probed with a $778$-nm laser in order to obtain the $ket{5S}rightarrowket{5D}$ transition frequency as a portable optical frequency standard. Optical traps can induce shifts that compensate those incurred by the probing lasers and confine the atoms to prevent residual Doppler effects, both of which would otherwise hamper the clock stability. Addressing the other two problems mentioned, circular-state Rydberg atoms that are able to be manipulated with optical lattices introduce a platform for high-resolution spectroscopy of their electronic transitions using very weak microwave fields. The long lifetimes of circular states, which approach 1~s, extend the probing times for a measurement of the Rydberg constant ($10^{-12}$ uncertainty) insensitive to the proton charge radius, and the existence of microwaves generated by axion couplings to the electromagnetic field. This dissertation explores the functionality of optical lattices as a tool that can contribute to the advancement of these aforementioned endeavors. In the first implementation of optical lattices for these goals, a measurement of the Rb $ket{5D_{3/2}}$ AC polarizability and photoionization cross section is performed using a cavity-enhanced optical lattice with an ultra-deep depth on the order of $sim10^{5}$ single-photon recoils. The lattice wavelength is $lambda=1.064~mu$m, which induces shifts on $ket{5D_{3/2}}$ that can be characterized by the measured scalar polarizability of $alpha^{S}_{5D_{3/2}}=-524(17)$~atomic units. I choose this wavelength because it is commonly available as a narrow-linewidth, high-powered laser. At this wavelength, photoionization induces decay of this energy level and broadening of spectral lines as evidence of the significant measured cross section $sigma_{PI}=44(1)$~Mb. The secondary use of lattices as a tool for fundamental physics concerns periodically driven ponderomotive potentials for the effort of initializing the circular states required for a Rydberg constant measurement and dark-matter detection. Experimentally, the principles are discussed in a newly developed lattice phase-modulation technique, where the $ket{46S_{1/2}}rightarrowket{46P_{1/2}}$ and $ket{48S_{1/2}}rightarrowket{49S_{1/2}}$ transitions were spectrocscopically measured with this driving mechanism. Additionally, the importance of cancelling stray electric and magnetic fields for this mechanism to be efficient is also demonstrated. The applicability of ponderomotive light-matter interactions for obtaining circular states is discussed in a theoretical proposal of all-optical circularization techniques.

•Jan 1, 2023•0 citations

High-Precision Spectroscopy Using Rydberg Atoms

Kaitlin Moore

Using cold atoms, I probe the energy-level intervals between Rydberg states to high spectroscopic precision. The focus of this work is to lay the groundwork for an updated, highly-controlled measurement of the Rydberg constant using circular-state Rydberg atoms, needed to resolve a recent conflict in proton-radius values that arose in 2010 (the so-called 'proton radius puzzle'). Toward this end, I have demonstrated a fundamentally-new mechanism with which to drive atomic (Rydberg-Rydberg) transitions, utilizing an inelastic (state-changing) ponderomotive interaction. Until now, the multipole-field interaction has been the sole mechanism on which spectroscopy of atomic transitions has been based. In this work, the state-changing ponderomotive interaction ('ponderomotive spectroscopy') is demonstrated by amplitude-modulating an optical standing wave at a transition resonance of a Rydberg atom. At the core of this new spectroscopic technique is the requirement that the light intensity must be modulated in space within the atomic volume, and in time at the desired atomic transition frequency. A Rydberg atom in a modulated optical lattice is very well-suited for a demonstration of this novel type of spectroscopy. Magic-wavelength conditions of this interaction are also identified, as well as a method to drive transitions at harmonics of the modulation. Both of these features of ponderomotive spectroscopy will be utilized to simultaneously trap and probe Rydberg atoms to perform the Rydberg constant measurement. I also present a high-precision measurement of the quantum defect of a high-angular-momentum state of rubidium, the atomic species that will be used in the Rydberg constant measurement. The quantum defects of high-angular-momentum states are needed to determine the effect of the rubidium core polarizability on the Rydberg constant measurement, which is anticipated to be a leading uncertainty. Finally, I present the background and design work for a measurement of the Rydberg constant specifically tailored to help resolve the proton radius puzzle, thereby completing the major preliminary work needed for the performance of that high-precision measurement.

•Jan 1, 2017•0 citations

Trapping Rydberg Atoms in Ponderomotive Optical Lattices.

Sarah Elizabeth Anderson

I examine the trapping of Rydberg atoms in an optical standing wave. This trap, called an optical lattice, offers a platform for utilizing Rydberg atoms and their unique properties in applications such as atomic spectroscopy and quantum computing. Toward this end, I demonstrate the capability to trap rubidium 85 Rydberg atoms in a one-dimensional 1064 nm wavelength optical lattice with high efficiency. I have achieved a 90% trapping efficiency by inverting the lattice immediately after Rydberg-atom excitation, using an electro-optic technique. In addition, I investigate the dependence of optical-lattice trapping potentials for Rydberg atoms on the angular portion of the atomic wavefunction. While ground-state atoms are point-like in relation to an optical-lattice field, Rydberg-atom wavefunctions extend over a substantial fraction of the lattice period, leading to an angular dependence of the lattice trapping potentials. I measure the potentials using various angular sublevels of Rydberg nD states prepared in the optical lattice with a superimposed transverse DC electric field. This unique angular dependence of Rydberg-atom optical lattices may be exploited to tailor the trapping potentials as needed for spectroscopy or quantum computing. Further, atom loss due to lattice-induced photoionization of Rydberg atoms must be characterized for applications. I investigate the photoionization process as a function of position within the volume of a Rydberg atom. Since Rydberg-atom sizes approximately equal the lattice period, the lattice intensity varies maximally within the atomic volume. I find that photoionization rates are higher for lattice intensity maxima located near the nucleus than within the lobes of the electronic probability distribution. Photoionization therefore occurs near the Rydberg-atom nucleus. Finally, I calculate photoionization rates for Rydberg atoms in optical fields and investigate how these rates relate to the validity of the electric dipole approximation. This approximation is usually central to matter-field interactions, and Rydberg atoms in optical fields present a system for studying the approximation in a limiting case. I further apply the photoionization calculations to experimentally-relevant conditions. With these advances, this thesis lays essential groundwork for the employment of Rydberg-atom optical lattices in applications.

•Jan 1, 2014•0 citations

Photoionization of Rydberg atoms in optical lattices

Ryan Cardman, Jamie MacLennan, Sarah Elizabeth Anderson +2 more

Abstract We develop a formalism for photoionization (PI) and potential energy curves (PECs) of Rydberg atoms in ponderomotive optical lattices and apply it to examples covering several regimes of the optical-lattice depth. The effect of lattice-induced PI on Rydberg-atom lifetime ranges from noticeable to highly dominant when compared with natural decay. The PI behavior is governed by the generally rapid decrease of the PI cross sections as a function of angular-momentum (ℓ), lattice-induced ℓ-mixing across the optical-lattice PECs, and interference of PI transition amplitudes from the lattice-mixed into free-electron states. In GHz-deep lattices, ℓ-mixing leads to a rich PEC structure, and the significant low-ℓ PI cross sections are distributed over many lattice-mixed Rydberg states. In lattices less than several tens-of-MHz deep, atoms on low-ℓ PECs are essentially ℓ-mixing-free and maintain large PI rates, while atoms on high-ℓ PECs trend towards being PI-free. Characterization of PI in GHz-deep Rydberg-atom lattices may be beneficial for optical control and quantum-state manipulation of Rydberg atoms, while data on PI in shallower lattices are potentially useful in high-precision spectroscopy and quantum-computing applications of lattice-confined Rydberg atoms.

arXiv:2102.09622•New Journal of Physics•Jun 1, 2021•10 citations
In this dissertation, I explore several aspects of Rydberg physics with laser spectroscopy. The experiments center around the use of a very deep, cavity-generated, one-dimensional optical lattice in a cold atom sample. The optical lattice produces elongated clouds of dense, cold atoms via dipole trapping and is able to generate extreme light shifts in the atoms due to its high intensity. I describe experiments which may be divided into two main classes. In the first, I use the dipole trap to prepare a dense sample of atoms for photoassociation of Rb atom pairs into diatomic Rydberg molecules. The Rydberg molecules are formed by low-energy scattering of the Rydberg electron of one atom from the other atom, which is a ground-state atom. This novel binding mechanism also has relevance for chemical physics. I present binding energy measurements for eight different cases of Rydberg molecules. The binding energies reveal information about electron-atom collisions, such as their scattering lengths, and about the spin couplings present within the molecular system. In the second class of experiments, I introduce two proposed measurements in which the optical lattice is ramped to very high intensity during the laser excitation, creating AC Stark shifts in the transition frequencies. In one measurement, low-lying atomic states are probed. Measurements of the light shifts are expected to yield data on the dynamic polarizability and the photoionization cross section of the 5D3/2D_{3/2}D3/2​-state in rubidium in a 1064-nm light field. I show corresponding preliminary experimental data. The polarizability and photo-ionization cross-section measurements will provide tests of atomic structure theory, which is important both at a fundamental level and for applications such as atomic clocks. In another proposed measurement, Rydberg atoms in the lattice experience ponderomotive shifts and strong mixing of their angular-momentum states, allowing direct optical excitation of the lattice-mixed high-angular-momentum states. I describe the theoretical basis and experimental preparation for spectroscopically characterizing the lattice-mixed states. The ability to optically excite selected high-angular-momentum states without the use of static or RF fields may be useful for quantum information processing and simulation.
In this dissertation I investigate cold Rydberg atoms and molecules in which the angular-momentum character of the quantum states involved strongly influences their properties and dynamics. In the first part I focus on long-range diatomic Rydberg molecules formed by a rubidium D-state Rydberg atom and a second rubidium atom in its ground state. Spectroscopic measurements of molecular binding energies are presented showing the effect of the Rydberg atom size and fine-structure coupling on the molecular potentials. A theoretical model is introduced that takes into account all relevant angular-momentum couplings between the molecular constituents, successfully reproducing experimental observations. Calculations of adiabatic potentials and binding energies, molecular-state lifetimes, electric and magnetic dipole moments are also presented. In the second part, I describe the production and magnetic trapping of cold circular Rydberg atoms. The circular Rydberg atoms are generated out of a cold gas of rubidium using the crossed-fields method and magnetically trapped. The trapping force is employed to induce center-of-mass oscillations of the trapped atom sample. Trap parameters and observed oscillation frequencies are used to measure the magnetic moments of the circular Rydberg atoms. Trap losses and the atomic internal-state evolution in the 300 Kelvin thermal background are also investigated.
Atoms cooled and trapped using laser light have become the backbone of modern quantum physics research. Various new applications based on laser-cooled atoms are in active development. The work described in this dissertation is dedicated to this endeavor. I present experimental and numerical investigations on several fundamental properties of the laser-cooled atoms in different quantum states and how they may translate into applications within several emerging atom-based technologies. First, I describe the precision measurements of the dynamic polarizability and photo-ionization cross-section at 1064-nm light of the 5D3/25D_{3/2}5D3/2​ state in rubidium, which is of interest for the portable atomic clocks. Two different spectroscopic methods are implemented to extract the polarizability from the experimental data. The results are statistically equivalent: -524(17) [-499(59)] atomic units from the first [second] method. The photo-ionization cross section of the 5D3/25D_{3/2}5D3/2​ state at 1064~nm is measured to be 44(1) Mb. The aforementioned photo-ionization cross section is suitable for efficient ion generation and the subsequent application in cold-atom-based ion sources. This is demonstrated in the second study presented here. The ion source employs a novel method to monitor the electric microfields of the ions using the Stark effect of the highly-excited (Rydberg) atoms seeded within the origin of the ion source. Rydberg atoms are extremely sensitive to electric fields and serve as an embedded real-time sensor and tracker of the ion-source performance because of their quasicontinuous creation and detection. The principles of such ion-microfield sensing are discussed and analyzed in detail and can be utilized in any cold-atom-based focused-ion-beam source. The hyperfine structure of the 4D3/24D_{3/2}4D3/2​ state in rubidium is investigated next. The measurement utilizes two-photon optical absorption spectroscopy and a detailed analysis of light shifts. All four hyperfine components are resolved in the experimental data. The magnetic-dipole and electric-quadrupole hyperfine constants are obtained to be 7.419(45) MHz and 4.19(19) MHz, respectively. Future applications of the 4D3/24D_{3/2}4D3/2​ state in optical atomic clocks and Rydberg-atom physics are discussed. Next, I investigate a Rydberg-atom-ion molecule bound by long-range multipolar forces. The molecule is the first example of a bound state between a Rydberg atom and an ion. Strong interactions between these two particles lead to large molecular binding energy (reaching a few GHz) and large binding length (exceeding 1 mumumum). The Born-Oppenheimer approximation does not hold for the Rydberg-atom-ion molecule because the motion of the Rydberg-atom nucleus is on the same timescale as the dynamics of the ion. The Born-Huang theory is utilized to investigate the resultant nonadiabatic dynamics of the molecule and to make the first fully quantum predictions of its lifetime as a function of the vibrational state and quantum principal number of the Rydberg atom. Lastly, I present a novel technique for atom interferometry that employs uninterrupted three-dimensional confinement and manipulation during the interferometric protocol. The atoms in the existing apparatuses have to follow several-meter-long trajectories along which various detrimental effects such as wave-packet dispersion erase useful phase information. ``Tractor atom interferometry" presented here promises to suppress the harmful effects and improve the interferometers’ sensitivity; provide flexible control over the atomic trajectories; and significantly reduce the experimental footprint. The suitability of this approach for measuring background acceleration (such as due to the gravitational field) is demonstrated. The sensitivity estimations, experimental considerations, and initial laboratory work are discussed.
Fundamental physics is concerned with the problems of defining fundamental constants, units of measurement, and searching for new forces and aspects of matter. Usually, the best way to resolve these inquiries is to have a precise knowledge of atomic energy levels and the transition frequencies in order for their quantum states to be manipulated. Spectroscopy is a tool that probes these atomic energy levels by observing the atom's response as the energy of the applied radiation is varied. Over the past century, spectroscopy using electromagnetic radiation has involved direct interactions with the atom's electric and magnetic multipole moments via the textbfAcdottextbfptextbf{A}cdottextbf{p}textbfAcdottextbfp term of the minimal coupling Hamiltonian. The work presented in this thesis utilizes such interactions with laser fields and goes a step further by exploring a novel light-matter interaction via the A2A^2A2 term. Leading problems in the field of fundamental physics include the commercialization of optical frequency standards with short-term stabilities beating 10−11/sqrttau10^{-11}/sqrt{tau}10−11/sqrttau and the discovery of new science arising from competitive precision measurements of the Rydberg constant and the detection of axion dark matter. Ultracold rubidium atoms subject to periodic optical potentials in standing waves of light known as optical lattices offer solutions to these problems. Rubidium atoms contained in miniaturized, glass vapor cells can be probed with a 778778778-nm laser in order to obtain the ket5Srightarrowket5Dket{5S}rightarrowket{5D}ket5Srightarrowket5D transition frequency as a portable optical frequency standard. Optical traps can induce shifts that compensate those incurred by the probing lasers and confine the atoms to prevent residual Doppler effects, both of which would otherwise hamper the clock stability. Addressing the other two problems mentioned, circular-state Rydberg atoms that are able to be manipulated with optical lattices introduce a platform for high-resolution spectroscopy of their electronic transitions using very weak microwave fields. The long lifetimes of circular states, which approach 1~s, extend the probing times for a measurement of the Rydberg constant (10−1210^{-12}10−12 uncertainty) insensitive to the proton charge radius, and the existence of microwaves generated by axion couplings to the electromagnetic field. This dissertation explores the functionality of optical lattices as a tool that can contribute to the advancement of these aforementioned endeavors. In the first implementation of optical lattices for these goals, a measurement of the Rb ket5D3/2ket{5D_{3/2}}ket5D3/2​ AC polarizability and photoionization cross section is performed using a cavity-enhanced optical lattice with an ultra-deep depth on the order of sim105sim10^{5}sim105 single-photon recoils. The lattice wavelength is lambda=1.064 mulambda=1.064~mulambda=1.064 mum, which induces shifts on ket5D3/2ket{5D_{3/2}}ket5D3/2​ that can be characterized by the measured scalar polarizability of alpha5D3/2S=−524(17)alpha^{S}_{5D_{3/2}}=-524(17)alpha5D3/2​S​=−524(17)~atomic units. I choose this wavelength because it is commonly available as a narrow-linewidth, high-powered laser. At this wavelength, photoionization induces decay of this energy level and broadening of spectral lines as evidence of the significant measured cross section sigmaPI=44(1)sigma_{PI}=44(1)sigmaPI​=44(1)~Mb. The secondary use of lattices as a tool for fundamental physics concerns periodically driven ponderomotive potentials for the effort of initializing the circular states required for a Rydberg constant measurement and dark-matter detection. Experimentally, the principles are discussed in a newly developed lattice phase-modulation technique, where the ket46S1/2rightarrowket46P1/2ket{46S_{1/2}}rightarrowket{46P_{1/2}}ket46S1/2​rightarrowket46P1/2​ and ket48S1/2rightarrowket49S1/2ket{48S_{1/2}}rightarrowket{49S_{1/2}}ket48S1/2​rightarrowket49S1/2​ transitions were spectrocscopically measured with this driving mechanism. Additionally, the importance of cancelling stray electric and magnetic fields for this mechanism to be efficient is also demonstrated. The applicability of ponderomotive light-matter interactions for obtaining circular states is discussed in a theoretical proposal of all-optical circularization techniques.
Using cold atoms, I probe the energy-level intervals between Rydberg states to high spectroscopic precision. The focus of this work is to lay the groundwork for an updated, highly-controlled measurement of the Rydberg constant using circular-state Rydberg atoms, needed to resolve a recent conflict in proton-radius values that arose in 2010 (the so-called 'proton radius puzzle'). Toward this end, I have demonstrated a fundamentally-new mechanism with which to drive atomic (Rydberg-Rydberg) transitions, utilizing an inelastic (state-changing) ponderomotive interaction. Until now, the multipole-field interaction has been the sole mechanism on which spectroscopy of atomic transitions has been based. In this work, the state-changing ponderomotive interaction ('ponderomotive spectroscopy') is demonstrated by amplitude-modulating an optical standing wave at a transition resonance of a Rydberg atom. At the core of this new spectroscopic technique is the requirement that the light intensity must be modulated in space within the atomic volume, and in time at the desired atomic transition frequency. A Rydberg atom in a modulated optical lattice is very well-suited for a demonstration of this novel type of spectroscopy. Magic-wavelength conditions of this interaction are also identified, as well as a method to drive transitions at harmonics of the modulation. Both of these features of ponderomotive spectroscopy will be utilized to simultaneously trap and probe Rydberg atoms to perform the Rydberg constant measurement. I also present a high-precision measurement of the quantum defect of a high-angular-momentum state of rubidium, the atomic species that will be used in the Rydberg constant measurement. The quantum defects of high-angular-momentum states are needed to determine the effect of the rubidium core polarizability on the Rydberg constant measurement, which is anticipated to be a leading uncertainty. Finally, I present the background and design work for a measurement of the Rydberg constant specifically tailored to help resolve the proton radius puzzle, thereby completing the major preliminary work needed for the performance of that high-precision measurement.
I examine the trapping of Rydberg atoms in an optical standing wave. This trap, called an optical lattice, offers a platform for utilizing Rydberg atoms and their unique properties in applications such as atomic spectroscopy and quantum computing. Toward this end, I demonstrate the capability to trap rubidium 85 Rydberg atoms in a one-dimensional 1064 nm wavelength optical lattice with high efficiency. I have achieved a 90% trapping efficiency by inverting the lattice immediately after Rydberg-atom excitation, using an electro-optic technique. In addition, I investigate the dependence of optical-lattice trapping potentials for Rydberg atoms on the angular portion of the atomic wavefunction. While ground-state atoms are point-like in relation to an optical-lattice field, Rydberg-atom wavefunctions extend over a substantial fraction of the lattice period, leading to an angular dependence of the lattice trapping potentials. I measure the potentials using various angular sublevels of Rydberg nD states prepared in the optical lattice with a superimposed transverse DC electric field. This unique angular dependence of Rydberg-atom optical lattices may be exploited to tailor the trapping potentials as needed for spectroscopy or quantum computing. Further, atom loss due to lattice-induced photoionization of Rydberg atoms must be characterized for applications. I investigate the photoionization process as a function of position within the volume of a Rydberg atom. Since Rydberg-atom sizes approximately equal the lattice period, the lattice intensity varies maximally within the atomic volume. I find that photoionization rates are higher for lattice intensity maxima located near the nucleus than within the lobes of the electronic probability distribution. Photoionization therefore occurs near the Rydberg-atom nucleus. Finally, I calculate photoionization rates for Rydberg atoms in optical fields and investigate how these rates relate to the validity of the electric dipole approximation. This approximation is usually central to matter-field interactions, and Rydberg atoms in optical fields present a system for studying the approximation in a limiting case. I further apply the photoionization calculations to experimentally-relevant conditions. With these advances, this thesis lays essential groundwork for the employment of Rydberg-atom optical lattices in applications.
Abstract We develop a formalism for photoionization (PI) and potential energy curves (PECs) of Rydberg atoms in ponderomotive optical lattices and apply it to examples covering several regimes of the optical-lattice depth. The effect of lattice-induced PI on Rydberg-atom lifetime ranges from noticeable to highly dominant when compared with natural decay. The PI behavior is governed by the generally rapid decrease of the PI cross sections as a function of angular-momentum (ℓ), lattice-induced ℓ-mixing across the optical-lattice PECs, and interference of PI transition amplitudes from the lattice-mixed into free-electron states. In GHz-deep lattices, ℓ-mixing leads to a rich PEC structure, and the significant low-ℓ PI cross sections are distributed over many lattice-mixed Rydberg states. In lattices less than several tens-of-MHz deep, atoms on low-ℓ PECs are essentially ℓ-mixing-free and maintain large PI rates, while atoms on high-ℓ PECs trend towards being PI-free. Characterization of PI in GHz-deep Rydberg-atom lattices may be beneficial for optical control and quantum-state manipulation of Rydberg atoms, while data on PI in shallower lattices are potentially useful in high-precision spectroscopy and quantum-computing applications of lattice-confined Rydberg atoms.