INTRODUCTION
Ion traps are a robust and promising platform for quantum information processing and for the implementation of a quantum computer. However, major challenges exist in scaling these systems to the level required for full-scale quantum computing. I will describe work concerned with addressing two of these challenges; namely connecting multiple trap zones in more than one dimension,...
Low energy positron beams are used in a variety of applications, including studies of atomic and condensed matter systems.[1] We study here the properties of a magnetically guided cold positron beam (generated in the conventional manner from a 22Na radioisotope source and solid neon moderator [2]) and their relationship to the different magnetic fields along the axis of a 7 m long scattering...
The thorium-229 nucleus possesses a unique first excited state at an energy of only about 7.8 eV, coupled to the ground state by a transition with a natural linewidth in the mHz range. This transition can be used as a reference for an optical clock that is highly immune to field-induced frequency shifts and as a sensitive probe of temporal variations of fundamental constants [1]. Despite many...
Precise measurements of the fundamental properties of the proton such as its mass, lifetime, charge radius, and magnetic moment are important for our understanding of the physics of atomic and nuclear structure as well as for tests of fundamental symmetries. As one of very few particle-antiparticle pairs which are directly comparable, the proton and antiproton serve as an important laboratory...
The coupling of ions stored in different traps through the charges they induce in a common electrode was proposed in Ref. [1], but it has not been
accomplished yet. The completion of such a system would be an outstanding technological breakthrough in quantum electronics and would pave the
way for the implementation of hybrids systems for quantum information [2]. A pioneer work using...
In contrast to a conventional electron-ion plasma, the electron-positron pair plasma is characterized by the mass balance of the two components. Theoretical studies thus predicted long time ago a fundamentally new insight into plasma physics by studying these plasmas. Only recently experimental activities have become more precise e.g. by the APEX project which aims for the creation of a...
Quantum resource theories seek to quantify sources of non-classicality that bestow quantum technologies their operational advantage. Chief among these are studies of quantum correlations and quantum coherence. The former to isolate non-classicality in the correlations between systems, the latter to capture non-classicality of quantum superpositions within a single physical system. Here we...
Following results of laser cooling a single ion of $^{40}$Ca$^+$ to its motional ground state ($\bar{n}_z=0.02(1)$) in the axial domain of a Penning trap [1], we report simultaneous sideband cooling of both radial modes to near their ground state in the same apparatus. Sideband cooling is performed on the $S_{1/2} \leftrightarrow D_{5/2}$ electric quadrupole transition at 729 nm, and average...
The former $g$-factor experiment located in Mainz performed various $g$-factor measurements on highly charged ions, resulting in tests of bound state QED [1] and the most precise value for the atomic mass of the electron [2]. These measurements will be continued within a new experiment at the MPIK with access to heavier highly charged ions. Meanwhile the follow-up experiment in Mainz, which is...
The high-precision Penning-trap mass spectrometer PENTATRAP (1) is currently being commissioned at the Max-Planck-Institut für Kernphysik in Heidelberg. It aims at mass-ratio measurements of stable and long-lived highly-charged ions with a relative uncertainty of below $10^{-11}$, a precision so far only achieved for a few relatively light elements (2).
The mass-ratio measurement is carried...
Abstract: Low temperature ion-atom interactions have been the object of growing interest over the past decade. Due to the availability of laser cooling for many atoms (Li, Na, K, Rb, Cs, Ca, Sr, Ba, Yb, etc.)[1,2,3] and ions (Ca+, Sr+, Ba+, Yb+ , etc)[4,6,7], the interactions between such ions and atoms have been explored experimentally at mK temperatures[5,7,8]. In the case of optically...
A number of upgrades and stabilisation techniques to the BASE apparatus [1], motivated by improving upon the recent 1.5 ppb measurement of the antiproton $g$-factor [2] and other fundamental properties of the antiproton, are presented.
A new modified-cyclotron mode detection system has been commissioned and installed into the BASE apparatus. The primary function of this instrument is to...
Antihydrogen, the bound state of a positron and an antiproton, is being studied by the ALPHA collaboration at CERN so that it can be compared to its matter counterpart, hydrogen. Antihydrogen is synthesised by merging plasmas of antiprotons and positrons in a magnetic trap, allowing a small fraction of the antihydrogen atoms created, the coldest, to remain trapped.
Decreasing the temperature...
Radio-frequency (rf) Paul traps operated with multifrequency rf trapping potentials provide the ability to independently confine charged particle species with widely different charge-to-mass ratios. In particular, these traps may find use in the field of antihydrogen recombination, allowing antiproton and positron clouds to be trapped and confined in the same volume without the use of large...
Several experiments at CERN aim at testing the CPT-theorem and weak equivalence principle using antimatter, among them the AEgIS experiment. Here, antihydrogen - produced via resonant charge exchange - will be used for precision measurements where the achievable sensitivity is determined by the temperature of the
antiprotons.
We are investigating laser-cooling of anionic molecules to...
Collinear laser spectroscopy (CLS) is a powerful tool, with a long and successful history at COLLAPS/ISOLDE, to access nuclear ground state properties such as spin, charge radius, and electromagnetic moments with high precision and accuracy [1]. Conventional CLS is based on the optical detection of fluorescence photons from laser-excited ions or atoms. It is limited to radioactive ion beams...
Bound state quantum electrodynamics is one of the most thoroughly tested theories in physics, but was recently challenged by measurements done on muonic atoms, where a discrepancy of >5$\sigma$ was reported between the nuclear charge radii extracted from spectroscopic measurements on muonic hydrogen and electronic hydrogen [1-4]. To gain new insights into the “proton radius puzzle” we aim to...
The ${}^{171}$Yb${}^+$ ion employed in our single-ion optical clocks features two transitions used for the realization of frequency standards, the ${}^2$S${}_{1/2}$ to ${}^2$D${}_{3/2}$ electric quadrupole (E2) $[1]$ and the ${}^2$S${}_{1/2}$ to ${}^2$F${}_{7/2}$ electric octupole (E3) $[2]$ transition. The E2 transition frequency shows a significantly higher sensitivity to frequency shifts...
Steven A. Jones (1) from the ALPHA collaboration (2)
1) Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark.
steven.armstrong.jones@cern.ch
2) CERN, CH-1211 Geneve 23, Switzerland
Antihydrogen offers a unique way to test matter/antimatter symmetry. Antihydrogen can reproducibly be synthesised and trapped in the laboratory for extended periods of time [1][2],...
We present techniques tailored for sympathetic cooling and manipulation of a single (anti-)proton in a Penning trap system. Inside our trap a double-well potential is engineered for co-trapping an atomic ion, which enables for the use of quantum logic spectroscopy inspired cooling and readout schemes [1, 2]. These should allow for preparation at sub-Doppler temperatures and a readout of the...
The trends of nuclear binding-energies, obtained from high-precision atomic mass values, are sensitive to a wide range of nuclear structure phenomenon such as shell effects or onsets of collectivity. Hence, binding energies enable to track down the evolution of nuclear structure in yet unexplored region of the nuclear chart, also providing essential inputs to many nuclear models.
Three...
The main goal of the GBAR (Gravitational Behaviour of Anihydrogen at Rest) experiment is to test the week equivalence principle for $\bar{H}$, which has never been measured directly. In order to perform that very complex experiment, ultracold antihydrogen atoms ($\approx 10 \mu K$) are needed. As it is impossible to cool down neutrals to required temperature, GBAR is going to produce the...
Nearly complete quantum control of individual trapped ions has become commonplace in many precision spectroscopy, metrology, and quantum information experiments. However, while measurements of the properties of fundamental particles for CPT tests have had remarkable recent successes [1, 2, 3], they have been limited to 0.3 ppb precision by long measurement times and particle temperatures on...
Recent advances in trapped ion quantum technology have led to impressive results including the demonstration of four qubit GHZ states using subsequent entanglement gates [1] and a dc magnetometer with quantum enhanced sensitivity [2]. We will present the underlying technological advancements, starting with a high-speed multi-channel waveform generator developed in Mainz. The system delivers...
Quantum electrodynamics (QED) is one of the best tested theories in physics [1]. However, energy levels in atomic hydrogen have been determined with much higher accuracy than what QED theory can provide, because it is hampered by the uncertainty in the experimentally determined proton charge radius. Therefore, spectroscopic measurements on muonic hydrogen ($\mu$H) were performed which improved...
The ALPHATRAP experiment is a Penning-trap setup dedicated to test bound-state quantum electrodynamics by determining the g-factor of the bound electron in the electric field of highly charged ions (HCI) with ultra-high precision.
The ALPHATRAP experiment is currently in the final stage of commissioning.
The setup exists of a cryogenic double Penning-trap tower in which the HCI can be stored...
The Penning-trap mass spectrometer ISOLTRAP located at the radioactive ion beam facility ISOLDE at CERN performs high-precision mass measurements of short-lived nuclides. This gives access to the study of nuclear structure effects like the location of shell and subshell closures and provides precision $\beta$-decay $Q$-values to test nuclear models and fundamental interactions. For three...
A cloud of trapped ions, represented here by a four level atomic system $\mid S_{1/2}>,\mid P_{1/2}>,\mid D_{3/2}>$ and $\mid D_{5/2}>$, is probed by the collection of photons from the transition $\mid P_{1/2}>$ to $\mid S_{1/2}>$.
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Figure : Four level atomic system of Ca+ ions
The lambda configuration with lasers at 866nm and 397nm allows for a two-photon dark state to take...
We report on our hybrid experiment which aims at studying trapped ions interacting with ultracold atoms that are off-resonantly coupled to Rydberg states. Since the polarisability of the Rydberg-dressed atoms can be extremely large, the interaction strength between ions and atoms increases tremendously as compared to the ground state case. Such interactions may be mediated over micrometers and...
