One of the most challenging quests for physicists was represented by the goal of trapping of atomic particles,in a well controlled environment. The advent of ion traps [1] in the 1950s, influenced the future of physics andtechnology in a very profound and even revolutionary mode. High-precision spectroscopy and mass spectrometrymeasurements with unprecedented accuracy, quantum physics tests, precise control of quantum states, study ofnon-neutral plasmas, quantum metrology and quantum information processing (QIP) experiments [2], have allbeen achieved by using ion and atom traps.In order to achieve trapping of electrically charged particles, the radio-frequency (RF) Paul trap has been de-signed, which creates an effective trapping potential in the
One of the most challenging quests for physicists was represented by the goal of trapping of atomic particles,in a well controlled environment. The advent of ion traps [1] in the 1950s, influenced the future of physics andtechnology in a very profound and even revolutionary mode. High-precision spectroscopy and mass spectrometrymeasurements with unprecedented accuracy, quantum physics tests, precise control of quantum states, study ofnon-neutral plasmas, quantum metrology and quantum information processing (QIP) experiments [2], have allbeen achieved by using ion and atom traps.In order to achieve trapping of electrically charged particles, the radio-frequency (RF) Paul trap has been de-signed, which creates an effective trapping potential in the
Ion traps are fantastic tools to explore the world of electrons, atomic and molecular ions, or charged clusters, in the classical as well as in the quantum regime. Extremely long storage times allow probing even of single particles with very high precision. The mass selectivity of the trapping devices is exploited in many experiments, in particular for mass metrology. An overwhelming part of the experiments and ideas rely on the very high level of parameter control which is offered by the ion trap. Manipulation of individual ions and engineering of well defined quantum states are the fundamental techniques to take the experiments beyond existing frontiers and to unprecedented precision. This special issue presents state-of-the-art theory and experiments in a variety of tutorials, reviews and research papers. More than half of these contributions form a follow-up to the first workshop on Modern Applications of Trapped Ions held in Les Houches, France, in May 2008. A great number of topics is covered in atomic and molecular physics, with ion traps as a common tool. The variety of approaches is meant to make this digest a helpful resource to the whole ion trapping community. Among the contributions, four major – while still overlapping – domains can be identified. Novel ion trap design is the motor of future developments and applications. Spectacular progress has been made in the domain of quantum information processing, such as the realization of planar traps, which opens the way to large-scale quantum computation. In this issue, this enthralling subject is introduced by a tutorial and two review articles, completed by contributions on different experimental realizations. Precision measurements belong to a more traditional domain which nevertheless evolves at the forefront of research: metrology of frequencies and fundamental constants, measurements of g-factors or high-precision mass measurements are the foundations of atomic and molecular physics. The creation and investigation of cold molecular ions and clusters are among the fastest growing topics, leading to ultracold chemistry at the single-particle scale. The next edition of this meeting series will take the name of European Conference on Trapped Ions (ECTI) and will be held in the UK in 2010. We are looking forward to this event, which will offer the possibility to continue the fruitful interaction between research groups that employ ion traps in widely different contexts, and to take the next snapshot of this dynamic research area.
Ion traps are fantastic tools to explore the world of electrons, atomic and molecular ions, or charged clusters, in the classical as well as in the quantum regime. Extremely long storage times allow probing even of single particles with very high precision. The mass selectivity of the trapping devices is exploited in many experiments, in particular for mass metrology. An overwhelming part of the experiments and ideas rely on the very high level of parameter control which is offered by the ion trap. Manipulation of individual ions and engineering of well defined quantum states are the fundamental techniques to take the experiments beyond existing frontiers and to unprecedented precision. This special issue presents state-of-the-art theory and experiments in a variety of tutorials, reviews and research papers. More than half of these contributions form a follow-up to the first workshop on Modern Applications of Trapped Ions held in Les Houches, France, in May 2008. A great number of topics is covered in atomic and molecular physics, with ion traps as a common tool. The variety of approaches is meant to make this digest a helpful resource to the whole ion trapping community. Among the contributions, four major – while still overlapping – domains can be identified. Novel ion trap design is the motor of future developments and applications. Spectacular progress has been made in the domain of quantum information processing, such as the realization of planar traps, which opens the way to large-scale quantum computation. In this issue, this enthralling subject is introduced by a tutorial and two review articles, completed by contributions on different experimental realizations. Precision measurements belong to a more traditional domain which nevertheless evolves at the forefront of research: metrology of frequencies and fundamental constants, measurements of g-factors or high-precision mass measurements are the foundations of atomic and molecular physics. The creation and investigation of cold molecular ions and clusters are among the fastest growing topics, leading to ultracold chemistry at the single-particle scale. The next edition of this meeting series will take the name of European Conference on Trapped Ions (ECTI) and will be held in the UK in 2010. We are looking forward to this event, which will offer the possibility to continue the fruitful interaction between research groups that employ ion traps in widely different contexts, and to take the next snapshot of this dynamic research area.
Since the birth of ion trapping techniques in the 1960s, physics and chemistry applications have evolved fruitfully in concert, leading to the award of one-quarter of the 1989 Nobel Prize in Physics to each of W. Paul [1] and H.G. Dehmelt [2]. Although radiofrequency ion traps were used largely for high resolution atomic spectroscopy, spin exchange experiences, and lifetimes of atomic levels [3,4], the so-called ‘QUISTOR’[5] (QUadrupole Ion STORe) opened a new vista in mass spectrometry not only for component analysis but also for studies of chemical reaction paths also. Atomic excitations that are employed in lasers and the subsequent manipulation of such atomic lasers have stimulated the realization of the huge possibilities presented by ion trapping. Laser cooling, which has permitted the attainment of extreme accuracy in atomic spectroscopy measurements, has provided the means for precise internal and external ion energy manipulation thus opening the way to novel and powerful applications, such as quantum information and atomic clocks in the optical domain [6]. In general, lasers afford quite extraordinary means for both the formation of monatomic and polyatomic ions in specic excitation states and for probing such species in excited states. Recent progress in the development of a wide range of lasers, including the advent of laser diodes, offers myriad opportunities for new kinds of investigations. Another important research direction was opened by the liberties taken with the hyperboloidal geometry of the quadrupole ion trap. Enhanced understanding of the connement properties of quadrupole ion traps allowed the exploitation of new geometries that were easier to construct, such as cylindrical ion traps that permitted ready access for experimentation, exploited new characteristics such an non-linear modes of excitation, and introduced a stretched geometry that led to improvement in mass resolution. Recently, miniaturization of cages [7] or traps on micro-chips [8] have been exploited in atomic quantum physics as well as in chemistry analysis.* It is worthy to note that the extent of progress made in each of these domains was realized due to the curiosity of researchers and their desire to learn from the results of the experiments carried out. The purpose of this chapter is to expound upon the specic topic of atomic clocks utilizing ion traps and the new challenges engaged presently for the measurement of time with extremely high precision. Today, ion atomic clocks are designed for various systems (that is, the ion-trap-oscillator ensemble) that could offer new opportunities for the design of new ion trapping applications.
Fundamental interactions and symmetries define the structure and properties of all matter, in particular of its small and diverse visible constituents—the atoms. The study of their distinctive spectra through precision spectroscopy is therefore a vital tool to advance our understanding of nature. Highly charged ions (HCIs) constitute the largest fraction of all atoms since every atom has as many charge states as electrons it can bind. Although most of the matter on Earth is neutral, HCIs are ubiquitous in the universe and their systematic study is essential not only for atomic physics but eminently for astrophysics, nuclear physics, and fusion research, among others. Recently, HCIs have been identified as ideal candidates for sensitive tests of physics beyond the Standard Model of particle physics and for use in future high-accuracy optical atomic clocks. However, the realization of such proposals has been hindered by the hitherto constrained laboratory control and limited spectroscopic accuracy of about parts-per-million fractional uncertainty levels. This thesis reports the first coherent laser spectroscopy of HCIs, boosting the achievable spectroscopic precision by eight orders of magnitude compared to traditional spectroscopy methods. The 2P1/2–2P3/2 fine-structure ground-state transition in highly charged 40Ar13+ at an optical wavelength of 441 nm was chosen as a proof-of-principle case. A single ion of this species was isolated from a megakelvin-hot plasma cloud and co-trapped together with a laser-cooled singly charged 9Be+ ion in a two-ion crystal, confined in the harmonic potential of a cryogenic linear Paul trap. This coupled quantum-mechanical system was then cooled to its ground state of axial motion, corresponding to the lowest temperature of a HCI ever achieved. The spectroscopy was realized by implementing quantum logic techniques which allow preparation of the quantum state of the HCI and to map its electronic state after spectroscopy onto the 9Be+ logic ion in order to detect it there with high efficiency through electron shelving. In addition to the increase of spectroscopic precision, the excited-state lifetime and g-factor were measured—the latter one to unprecedented accuracy, resolving effects from special relativity, interelectronic interactions, and quantum electrodynamics. Moreover, it settled a discrepancy between theoretical predictions. The demonstrated techniques are not limited to the specific 40Ar13+ species but universally applicable to other HCIs. Thereby, this work unlocks the potential of HCIs for unrivaled tests of fundamental physics, the search for new physics—such as a 5th force, variations of fundamental constants and dark matter candidates—as well as the use of HCIs in novel optical atomic clocks.
Resolved-sideband cooling of a single 9Be+ ion in a Penning trap
Manipulating individual trapped ions at the single quantum level has become standard practice in radio-frequency ion traps, enabling applications from quantum information processing to precision metrology. The key ingredient is ground-state cooling of the particle's motion through resolved-sideband laser cooling. Ultra-high-presicion experiments using Penning ion traps will greatly benefit from the reduction of systematic errors offered by full motional control, with applications to atomic masses and g-factor measurements, determinations of fundamental constants or related tests of fundamental physics. In addition, it will allow to implement quantum logic spectroscopy, a technique that has enabled a new class of precision measurements in radio-frequency ion traps. Here we demonstrate resolved-sideband laser cooling of the axial motion of a single 9Be+ ion in a cryogenic 5 Tesla Penning trap system using a two-photon stimulated-Raman process, reaching a mean phonon number of nˉz=0.10(4). This is a fundamental step in the implementation of quantum logic spectroscopy for matter-antimatter comparison tests in the baryonic sector of the Standard Model and a key step towards improved precision experiments in Penning traps operating at the quantum limit.
Abstract Isolating neutral and charged particles from the environment is essential in precision experiments. For decades, this has been achieved by trapping ions with radio-frequency (RF) fields and neutral particles with optical fields. Recently, the trapping of ions by interaction with light has been demonstrated. This might permit the advantages of optical trapping and ions to be combined. For example, we would benefit from superimposing optical traps to investigate ensembles of ions and atoms in the absence of any RF fields and from the versatile and scalable trapping geometries featured by optical lattices. In particular, ions provide individual addressability, and electronic and motional degrees of freedom that can be coherently controlled and detected via high-fidelity, state-dependent operations. Their long-range Coulomb interaction is significantly larger compared to those of neutral atoms and molecules. This enables ultra-cold interaction and the chemistry of trapped ions and atoms to be studied, as well as providing a novel platform for higher-dimensional experimental quantum simulations. The aim of this topical review is to present the current state of the art and to discuss the current challenges and prospects of the emerging field.