Hybrid quantum systems integrate laser-cooled trapped ions and ultracold quantum gases within a single experimental configuration, offering vast potential for applications in quantum chemistry, polaron physics, quantum information processing, and quantum simulations. In this study, we introduce the development and experimental validation of an ion trap chip that incorporates a flat atomic chip trap directly beneath it. This innovative design addresses specific challenges associated with hybrid atom-ion traps by providing precisely aligned and stable components, facilitating independent adjustments of the depth of the atomic trapping potential, and positioning trapped ions. Our findings include the simultaneous loading of the ion trap with linear Yb+ ion crystals and the loading of neutral 87Rb atoms into a mirror magneto-optical trap.
Hybrid quantum systems integrate laser-cooled trapped ions and ultracold quantum gases within a single experimental configuration, offering vast potential for applications in quantum chemistry, polaron physics, quantum information processing, and quantum simulations. In this study, we introduce the development and experimental validation of an ion trap chip that incorporates a flat atomic chip trap directly beneath it. This innovative design addresses specific challenges associated with hybrid atom-ion traps by providing precisely aligned and stable components, facilitating independent adjustments of the depth of the atomic trapping potential, and positioning trapped ions. Our findings include the simultaneous loading of the ion trap with linear Yb+ ion crystals and the loading of neutral 87Rb atoms into a mirror magneto-optical trap.
Hybrid Trapping of 87Rb Atoms and Yb+ Ions in a Chip-Based Experimental Setup
Hybrid quantum systems that unite laser-cooled trapped ions and ultracold quantum gases in a single experimental setup have opened a rapidly advancing field of study, including Quantum chemistry, polaron physics, quantum information processing and quantum simulations. We present a fully developed and tested ion trap chip and propose a flat chip trap that can be placed beneath the ion trap. This design substantially addresses the difficulties specific to hybrid traps and features well-aligned chips that allow for independent adjustment of the depth of the atomic trap and the confinement and positioning of ions. The ion trap has been successfully tested with linear ion crystals of Yb+ and neutral 87Rb were also loaded into a mMOT a few millimeters under the ion trapping region.
In order to study interactions of atomic ions with ultracold neutral atoms, it is important to have sub‐µm control over positioning ion crystals. Serving for this purpose, a microfabricated planar ion trap featuring 21 DC electrodes is introduced. The ion trap is controlled by a home‐made FPGA voltage source providing independently variable voltages to each of the DC electrodes. To assure stable positioning of ion crystals with respect to trapped neutral atoms, the authors integrate into the overall design a compact mirror magneto optical chip trap (mMOT) for cooling and confining neutral 87Rb atoms. The trapped atoms will be transferred into an also integrated chip‐based Ioffe‐Pritchard trap potential formed by a Z‐shaped wire and an external bias magnetic field. The authors introduce the hybrid atom–ion chip, the microfabricated planar ion trap, and use trapped ion crystals to determine ion lifetimes, trap frequencies, positioning ions, and the accuracy of the compensation of micromotion.
In this PhD thesis, we describe the design and construction of an experimental apparatus capable of trapping, cooling and spatially overlapping neutral 6Li atoms and Yb+ ions. Our main goal is to reach the quantum regime in atom-ion mixtures and to investigate fundamental atom-ion scattering physics. In particular, we answer two important questions: 1) How does the atom-ion quantum simulator behave when we include micromotion in its theoretical description? To answer this question, we analyze in theory the quantum dynamics of an atom-ion quantum simulator unit cell in which a single atom interacts with a single trapped ion. 2) Is the combination Yb+/Li suitable for the experimental applications intended? To find this out we experimentally establish if the chemical reaction rate in colliding Li–Yb+ systems is low enough to allow for quantum applications and sympathetic cooling.
Hybrid ion-atom systems combine the well-controllable platforms of trapped ions and ultracold quantum gases and link them together by the intermediate-range ion-atom interaction. These quantum systems offer opportunities for buffer gas cooling, quantum simulation of many-body systems, as well as state-to-state quantum chemistry [1]. To fully benefit from the combination, it is essential to understand, characterize, and control the interactions between the atoms and ions. At TU/e, a new experimental setup is being built to go beyond alkali hybrid atom-ion systems and exploit the novel combination of a trapped ion – Yb+ - with dipolar atoms - Dy. This mixture offers new opportunities and here we present the progress made on developing it.
Hybrid ion-atom systems combine the well-controllable platforms of trapped ions and ultracold quantum gases and link them together by the intermediate-range ion-atom interaction. These quantum systems offer opportunities for buffer gas cooling, quantum simulation of many-body systems, as well as state-to-state quantum chemistry. To fully benefit from the combination, it is essential to understand, characterize, and control the interactions between the atoms and ions. At TU/e, a new experimental setup to go beyond alkali atom-ion hybrid system and exploit the combination of a trapped ion – Yb+ - with dipolar atoms - Dy. This mixture offers new opportunities and here we present the most recent results.
Hybrid quantum systems represent one of the most promising routes in the progress of experimental quantum physics and in the development of quantum technologies. In a hybrid quantum system two (or more) different quantum systems interact in the same experimental setup. Therefore, these composite systems benefit from both the properties of each single system and from the presence of an interaction term, leading to the emergence of new variables that can be experimentally manipulated. \nA promising hybrid quantum system is the one realized by the com- bination of an ultracold atomic gas and trapped ions. Ultracold atoms and trapped ions are two of the most studied physical systems for the implementation of several quantum technologies, like e.g. quantum simulation, quantum computa- tion, and quantum metrology. When trapped together, atoms and ions interact via an interaction potential that scales asymptotically with R^(−4), where R is the inter- particle distance, due to the electrostatic (attractive) force between the ion’s electric monopole and the atom’s induced dipole. Interestingly, this potential has a typical range on the order of hundreds of nm, i.e. approx. two orders of magnitude longer than the range of atom-atom interactions. Several studies have proposed to use this interaction to realize new quantum simulations, study few-body physics, and control atom-ion chemical reactions. \nElastic collisions between ions and atoms can be exploited to sympathetically cool the ions and try to reach the so-far elusive s-wave scattering regime, in which atom- ion collisions can lead to a quantum coherent evolution of the composite system. However, the ultracold atom-ion mixtures realized so far were not brought to the s-wave scattering regime because of the so-called “micromotion”, a driven motion affecting the dynamics of the ions trapped in Paul traps. Atom-ion collisions in the presence of micromotion cause a coupling of energy from the oscillating field of the Paul trap to the colliding particles, which can be heated up in the collision. In order to realize an atom-ion experiment in which the system could reach the s-wave scattering regime, the choice of the atomic species and the ion trapping strategy are crucial. \nWe decided to build a new experimental apparatus for the realization of an ultracold atom-ion quantum hybrid system made of a quantum gas of fermionic Lithium and trapped Barium ions. The choice for the elements ensures that atoms and ions in their electronic ground state will not undergo charge- exchange collisions, i.e. inelastic processes for which an electron is “exchanged” be- tween the two colliding particles. Additionally, the large mass ratio ensures an efficient cooling of the ion in the ultracold gas. \nFor what regards the ion trapping strategy, in order to remove the limitations set by micromotion, we conceived a new trap. This is formed by the superposition of an electric quadrupole static potential and an optical lattice along the untrapping direction of the electric quadrupole. The ions are moved into this electro-optical trap (EOT) from a standard Paul trap, in which the ions are first trapped after their production through photoionization. \nIn this thesis, I will describe how this new experimental apparatus for the real- ization of an ultracold atom-ion quantum hybrid system was conceived, designed and assembled. I will first describe the motivations for investigating atom-ion interactions in the ultracold regime. Then, I will describe the experimental techniques to trap and cool Barium ions and Lithium atoms, and how we plan to make them interact. The largest part of the thesis will be dedicated to the description of the parts of the experimental setup that I designed and realized, like the Lithium optical setup, the Barium imaging system and the electrical setup of the ion trap, including a compact RF drive based on interdependent resonant circuits that I developed for operating the Paul trap. The last chapter of the thesis is dedicated to this innovative drive.