Our quantum computer consists of a chain of trapped 171Yb+ ions with individual Raman beam addressing and individual readout. This fully connected system can be configured to run any sequence of single- and two-qubit gates, making it in effect an arbitrarily programmable digital quantum computer. The high degree of control can be used for digital, but also for analog and hybrid quantum...
In this talk, I will present experiments carried out with long ion strings and planar ion crystals with engineered long-range spin-spin interactions. In a first experiment, we variationally prepare low- and high-energy states of a nearest neighbor Heisenberg spin chain. Subsequently, measurements are carried out to learn the entanglement Hamiltonian describing subsystems of the spin chain that...
To apply today's quantum hardware to challenging problems, we need to efficiently use native interactions while minimizing the effects of noise. While operations on trapped ion qubits can be first-order resilient to noisy electric fields, deep computations with long ion chains suffer from high axial temperatures. To counter this, we employ sympathetic cooling in $^{171}$Yb$^+$-$^{172}$Yb$^+$...
Coupling a spin qubit to a mechanical system provides a route to prepare the mechanical system's motion in nonclassical states, such as a Fock state or an entangled state. Such quantum states have already been realized with superconducting qubits coupled to clamped mechanical oscillators. We are interested in achieving an analogous coupling between a spin and a levitated oscillator — namely, a...
One of the hallmarks of quantum mechanics is the impossibility of perfectly distinguishing non-orthogonal states. Extending this to the task of discriminating among quantum channels (such as unitary evolution or projective measurements) reveals a far richer problem, where seemingly non-orthogonal channels can sometimes be distinguished with certainty with only a few queries of the channel....
The application of existing telecom fiber infrastructure for quantum communication protocols enables efficient development of quantum networks [1]. It also entails multiple challenges, since existing infrastructure in an urban region is often underground or paired with the electrical overhead power line, and prone to environmental influences which cause fluctuations in polarization mode...
The analogue simulation of a quantum chemical system is challenging using conventional computers, particularly in strong vibronic (vibrational and electronic) coupling regimes when the Born-Oppenheimer approximation breaks down. The vibronic terms in Hamiltonians representing ultrafast molecular dynamics can be efficiently simulated on quantum systems with coupled internal states and bosonic...
A versatile magnetometer must deliver a readable response when exposed to targets fields in a wide range of parameters. In this work, we experimentally demonstrate that the combination of a $^{171}\mathrm{Yb}^+$ atomic sensor with adequately trained neural networks enables the characterization of target fields in challenging scenarios. In particular we estimate parameters of radio frequency...
Traditionally, molecules were considered too complicated for coherent quantum control. Recent molecular-ion-trapping developments enabled trapping, ground-state cooling, high-fidelity state detection, precision spectroscopy, coherent manipulation, and atom-molecule entanglement. Nowadays, molecule diversity and the variety of molecular degrees of freedom open new research directions that are...
We have built a microfabricated surface trap with integrated chip capacitors for quantum computation and simulation experiments. The trap features two loading zones at both sides for isotope selection and a central quantum operation region. We fabricate a series of parallel plate capacitors on chip with each capacitance around 800 pF to shunt the pick-up RF noise to the ground. The trap is...
Coherently manipulated crystals of ions in a Penning trap are a promising candidate for near-term quantum simulation of complex many-body phenomena and the search for dark matter using quantum sensing [1]. At the University of Sydney, we developed a Penning trap to perform such experiments with crystals containing hundreds of beryllium ions [2]. This contribution introduces this system and two...
Trapped-ion based quantum computers rely on frequency and phase locked lasers to perform experiments. Conventionally, this requires the use of bulky RF electronics that hinder scalability as well as inject noise into the system. In this poster, I will discuss the performance of a frequency/phase locking PCB that we have designed to allow for a more efficient and compact beat-note...
We designed an ion trap with integrated fiber cavities for enhanced coupling between single ion and photons. We fabricated the fiber electrodes covered with metal except for the light-through region by a series of processes including etching, CO2 laser ablation, lithography, magnetron sputtering, stripping, and electroplating. Its metallic part can be used both to provide the voltage required...
Abstract Advances in research such as quantum information and quantum chemistry require subtle methods for trapping particles (including ions, neutral atoms, molecules, etc.). Here we propose a hybrid ion trapping method by combining a Paul trap with optical tweezers. The trap combines the advances of the deep-potential feature for the Paul trap and the micromotion-free feature for the optical...
Motional modes of trapped ions have been shown to be a useful tool for quantum sensing, making use of time reversal protocols. This application requires the ability to prepare well-defined motional states with high fidelity. Many of these states can be generated from motional ground states without the use of laser fields. We report our results in generating one-mode and two-mode squeezed...
Ultracold trapped ions in linear radiofrequency traps are well-established and highly controllable quantum systems with a variety of applications in fields such as precision spectroscopy, cold chemistry, quantum information and optical clocks. Nanomechanical oscillators are highly sensitive objects for the development and implementation of technologies in miniaturized devices. Their nanoscopic...
In this work we show theoretically and experimentally how to use dark resonances emerging from coherent population trapping (CPT) in a multi-level lambda-type system as local electric field and temperature probes. To do this, we include a third laser to the system to avoid optical pumping effects. We find that the nature of the dark resonances can be either preserved or affected by the...
A dedicated control system is pivotal for sophisticated experiments in atomic, molecular and optical (AMO) physics. In particular, large-scale ion-trap and neutral atom quantum computing will require some of the most complex control systems ever built. These will need to support measurement-heavy workflows, fast feedback with tight latency constraints, and be scalable in hardware and software....
We’ve designed and built a high-pass optical bladetrap, with the ability to achieve NA=0.66 in two laser directions and NA=0.37 in the other two. This bladetrap has excellent performance: the vacuum can reach 7*10^-17 Torr at room temperature, and the Q value of helical can reach 280. Combined with optical and electronic scheme, we demonstrate a low-crosstalk optical double-side addressing...
Single-qubit rotations and a two-qubit entangling gate form a universal set of quantum logic gates[1]. In this work, we realize such a two-qubit computational register that is compatible with the quantum charge-coupled device (QCCD) architecture. Quantum logic operations are implemented using embedded microwave conductors. Single-qubit gates in two-ion crystals are performed by addressing each...
One of the challenges of ion-trap based quantum computers is their scalability. With an increasing number of qubits and parallelization of computation junctions and ion transport become necessary. A surface quantum charged coupled device architecture is a promising approach to tackle this challenge. Storage registers are needed for temporarily storing ions inbetween excecuting individual gate...
Quantum simulation area promising approach for understanding the dynamics governed by quantum field theories in the strong coupling regime. However, a lot of qubits and gates are required due to the presence of bosons in these models. Taking advantage of the available bosonic degrees of freedom in the quantum system can potentially help with this problem. In this talk, we propose a scheme to...
Quantum mechanics has overturned people's traditional cognition, and the superposition contradicts the fact that objects in our daily life are always in a certain state. Leggett and Garg proposed the Leggett-Garg inequality (LGI) to verify the existence of macroscopic superposition states. Classical systems are limited by LGI, while quantum systems may violate LGI. LGI provides an observable...
As the simplest molecules, molecular hydrogen ions (MHIs) are calculable, with ab initio theory reaching uncertainties for the prediction of transition frequencies only a factor of 10 larger than those achieved for the hydrogen atom [1]. They thus offer great potential for the extraction of fundamental constants as well as for tests of QED and search for BSM physics.
We present an overview...
Chip-based trapping technology has emerged as a promising approach for multi-dimensional quantum simulations and entanglement using individually controllable trapped ion qubits arrays. Previous studies have demonstrated successful local control, inter-site coupling, and floquet-engineered couplings in such architectures[1-3]. Here we present the extension of the existing toolbox by introducing...
One of the most formidable challenges of scaling up quantum computers is that of control signal delivery. Today’s small-scale quantum computers typically connect each qubit to one or more separate external signal sources. This approach is not scalable due to the I/O limitations of the qubit chip, necessitating the integration of control electronics. However, it is no small feat to shrink...
The combination of the entangling Mølmer–Sørensen gate and single qubit rotations
is a well-established method to realise a universal set of quantum gates using trapped ions. Implementing this gate scheme using global microwave fields can further the scaling prospects of this quantum computing platform, by reducing the complexity of the laser system required. [1]
Our approach uses current...
The integration of photonic components in surface electrode traps is a promising approach for scalable quantum computing with trapped ions [1].
Integrated photonics enables efficient delivery of laser light to the trap chip. Beams can be tightly focused on the ions, reducing power requirements, and a given configuration of laser fields can be reliably reproduced in different zones of the...
Quantum correlations, both spatial and temporal, are the central pillars of quantum mechanics. Over the last two decades, a big breakthrough in quantum physics is its complex extension to the non-Hermitian realm, and dizzying varieties of novel phenomena and applications beyond the Hermitian frame work have been uncovered. However, unique features of non-Hermitian quantum correlations,...
Using quantum annealing algorithms to solve optimization problems represents a promising path to achieving a practical quantum advantage in the NISQ era. Problems of interest are typically formulated as a quadratic unconstrained binary optimization (QUBO) and then encoded into a spin glass Hamiltonian with two-body spin interactions.
Recently the inclusion of higher-order terms into the...
An attractive proposition to extend the capabilities of quantum information systems is to fully utilise their high-dimensional Hilbert space. The internal electronic structure of trapped atomic ions offers a natural way to encode information not just in a two-level system, but in a high-dimensional qudit instead. One of the challenges of this approach is to achieve high fidelity interactions...
Topological transitions between different types of triply degenerate points are experimentally observed with a trapped ion. Recently, the remarkable discovery of topological semimetals with triply degenerate points in Fermionic systems provides an avenue for exploring new types of quasiparticles beyond quantum field theory. Such triply degenerate points are naturally characterized by high-rank...
Accurately measuring the potential generated by electrode of a Paul trap is of great importance for either precision metrology or quantum computing using ions in a Paul trap. For a rectangular shaped electrode, we find a simple and highly accurate parametric expression of the spatial field distribution. Using this expression, a method based on multi-objective optimization is presented to...
The Mølmer–Sørensen (MS) scheme has facilitated Quantum Simulation of Ising-type ($J_{ij}^x \sigma_x^i \sigma_x^j \;$) interacting-spin-systems, leveraging collective motional-modes of ions. However, only a few experiments explored more complex models, like XY models that can simulate novel many-body systems such as superfluids and spin-liquids. Existing protocols used modified MS schemes...
The integration of qubit control and readout elements into microfabricated surface-electrode ion traps offers potential advantages for scaling to larger trapped-ion systems. We report progress on two efforts in this direction. First, we present measurements of improved trap-integrated superconducting photon detectors for qubit fluorescence readout. The detectors are shielded from the trap rf,...
Remote entanglement using a quantum network has applications in distributed quantum computation, long-range quantum sensing, and secure quantum communication. Trapped ions present unique advantages as the quantum repeater node of a quantum network due to the ability to precisely prepare, control, and manipulate each qubit, perform high fidelity operations between qubits, and maintain...
The nature of dark matter (DM) and its interaction with the Standard Model (SM) is one of the biggest open questions in physics nowadays. Ultralight DM coupling to the SM induces oscillations in fundamental constants that are detectable by comparing clocks with different sensitivities to DM. Vibrational transitions of molecular clocks are more sensitive than electronic transitions of optical...
In the long-term, fault-tolerant (FT) quantum information processing is the central promise to demonstrate a quantum advantage for practical problems. However, in the current era of Noisy-Intermediate Scalable Quantum (NISQ) devices, low distance quantum error-correcting (QEC) codes and quantum error mitigation methods pave the way to today’s quantum reliable hardware. Unlike QEC techniques,...
Optical tweezers offer new opportunities to control and manipulate trapped ions with applications in quantum information processing. Two techniques to implement quantum logic gates have been theoretically developed in our group. These are based on qubit state-dependent potentials delivered by optical tweezers in combination with either electric fields [1], or strong polarization gradients in...
The Strontium ion is an ideal candidate for medium-distance quantum networking due to an atomic transition at 1.1 $\mu$m, a wavelength compatible with existing fiber optic infrastructure. This transition eliminates the need for lossy photon conversion processes, allowing for direct remote entanglement on the kilometer scale. We report on current progress towards ion-photon entanglement in a...
Conical intersections (CIs) are an ever-present phenomenon in chemistry and molecular physics that mark the crossing of energy levels on an adiabatic potential energy surface (PES). Around such intersections, the Born-Oppenheimer approximation breaks down and the coupling between electronic and nuclear coordinates becomes important. Thus, efficiently simulating the dynamics in the vicinity...
Quantum network is of great importance to the development of quantum communication, quantum computation and quantum metrology. With photon interference, separate quantum nodes can be entangled to build large-scale quantum information processor. However, its scaling up is facing with the challenge of quantum memory decoherence from photonic interfaces. To avoid disturbance, in trapped ion...
Trapped ions constitute one of the most promising systems for implementing quantum computing and networking. For large-scale ion-trap-based quantum computers and networks, it is critical to have two types of qubit: one for computation and storage, and another for auxiliary operations such as qubit detection, sympathetic cooling and entanglement generation through photon links. Previously, it...
Being a prospective platform for quantum computing and metrology, Coulomb
crystals of ultracold trapped ions currently reach sizes of hundreds of
individual particles. Such systems require high level of control over their
motional temperature in order to account for the second-order Doppler shift in
atomic clocks and implement high-fidelity entangling gates in quantum
computers. However,...
Forming antiprotonic atoms and their investigation is one of the goals of the AEgIS project at CERN. An intermediate stage of such an experiment is preparing a set of negative, atomic ions, co-trapped with antiprotons in a Penning trap. Such anions must be delivered in a single pulse, which requires an efficient, well-controlled, pulsed source of the ions.
Since attachment of electrons to...
We theoretically examine the effects of spontaneous emission at high magnetic fields for multi-qubit entangling operations on large ion crystals, and compare different gate types, laser beam detunings and polarizations, magnetic field strengths, and ion species. We show that the current configuration in the Penning trap at NIST is approximately ideal for light-shift (LS) gates in $^9$Be$^+$...
We summarize Quantinuum’s progress in research and development of surface-electrode ion traps for QCCD quantum computing architectures. This includes additional information about the racetrack trap in the commercially available H2 computer as well as design and experimental progress towards 2D ion trap grids planned for next-generation commercial computers.
We present here an experiment focusing on the extension of sympathetic cooling techniques to the unfavourable case of large mass ratios between the two ionic species involved and for ions injected from outside the trap. This study is essential to the success of ambitious projects such as the GBAR (Gravitational Behaviour of Antihydrogen at Rest) project aiming to study the free fall of a...
Molecular ions exhibit a rich internal structure attributed to their vibrational and rotational degrees of freedom. However, at room temperature, the rotational energy level populations are widely distributed due to black body thermalization, and the numerous decay pathways make direct laser cooling of molecules challenging at best, and impossible at worst. Therefore, we aim to demonstrate a...
Trapped-ion quantum sensors have become highly sensitive tools for the search of physics beyond the Standard Model. We present our recent measurements on the test of local Lorentz -invariance (LLI) with a single Yb+ ion [1] and isotope shift measurements for the search of the fifth force mediated by a potential dark matter boson [2,3].
In the attempt to unify all fundamental forces at the...
The dipole-phonon interaction (DPI) between the permanent dipole of a diatomic molecular ion and the secular oscillation of the ion chain manifests as a Jaynes-Cummings-type interaction. When combined with quantum logic, this interaction can enable state preparation and measurement of quantum information encoded within a molecular ion [1,2]. Here, we report on our progress toward observing...
Single-ion optical atomic clocks have reached fractional uncertainties of 1 part in $10^{-18}$ [1], but reaching this level of uncertainty requires long averaging times. Using $n$ uncorrelated ions, the same uncertainty could be obtained $n$ times quicker. If these $n$ ions could be placed in an entangled state however, speed-ups beyond this standard quantum limit are in principle possible...
Trapped ions have proved to be a promising way of realising a large-scale quantum computer. They allow for simple reproducibility and modular architectures which is crucial for a scalable, universal quantum computer. Our blueprint for a trapped-ion based quantum computer outlines operating with global microwave (MW) fields to dress the ground-state hyperfine manifold of 171Yb+ ions [1]. By...
Ultrafast spin-phonon entanglement based on SDKs provides an approach to realize fast entangling gates with intrinsic robustness and scalability for trapped ion quantum computing. Such SDKs so far have been implemented on a nanosecond timescale by off-resonant Raman transitions where each laser pulse is split into a sequence of perturbation pulses with carefully designed temporal...
Coulomb crystals, formed by cold trapped ions, represent a leading platform for realizing quantum processors, simulators, and constructing optical atomic clocks. The coupling between collective motion and internal degrees of freedom, resulting in quantum correlations, plays a pivotal role in achieving and enhancing these applications. However, at times, these quantum correlations can also...
Trapped ions are ideal systems for optical atomic clocks and precision tests of fundamental physics. However, the quantum projection noise of the single ion imposes a limit on its stability. Multi-ion optical clock has an obvious potential to improve clock stability. However, their operation has so far been impeded due to the challenges of controlling the various inhomogeneous shifts that are...
I will discuss the ups and downs of buffer gas cooling of trapped ions in the ultracold regime [1-3]. I will focus on attainable temperatures, collision energies and possible issues such as spin exchange and relaxation during atom-ion collisions [4] as well as trap-assisted complexes that can arise after an atom-ion collision [5]. I will discuss the prospects of using the system to explore...
Atoms with a highly excited electron, called Rydberg atoms, can form unusual types of molecular bonds. The bond differs from the well known ionic and covalent bonds not only by its binding mechanism, but also by its bond length ranging up to several micrometres. We report the observation a new type of molecular bond based on the interaction between the ionic charge and a flipping induced...
Rydberg atoms arrays are one of the most promising platforms for quantum simulation. Alkali ground-state atoms, trapped in optical tweezers, are arranged into a well-defined arbitrary geometry before being transferred into low-angular momentum Rydberg states using laser pulses. Once in a Rydberg level, the atoms interact with each other through the dipole-dipole coupling, which enables to...
Precision measurements of fundamental properties of protons and antiprotons constitute stringent tests of the fundamental interactions. Comparisons of their charge-to-mass ratios and magnetic moments have been used to constrain potential violations of CPT invariance, asymmetric particle-antiparticle dark matter couplings, and antiproton gravitational anomalies.
The BASE collaboration has...
Highly charged ions (HCI) have long been proposed for the application in optical clocks due to their extreme atomic properties. This allows for tests of fundamental physics and promises a systematic uncertainty that can compete with the state-of-the-art [1]. However, their application as frequency references has long been impeded by the megakelvin temperatures at which HCI are typically...
The 171Yb+ ion features two narrow optical transitions: an electric octupole (E3) transition as well as an electric quadrupole (E2) transition. Because they have a large differential sensitivity to the fine structure constant α, its possible variations can be probed by comparing the transition frequencies at various positions in spacetime. We find improved bounds on a linear temporal drift of...
The different effective dipole moment of conformational isomers allows for their spatial separation by means of electrostatic deflection, enabling their individual reactivity to be investigated [1]. Recently, the conformer-specific polar cycloaddition of dibromobutadiene (DBB) with trapped propene ions has shown that both gauche and s-trans DBB conformers display capture-limited reaction...
Strong ionizing radiation fields are ubiquitous in astrophysical environments. There, atomic matter appears mainly as highly charged ions (HCIs), which dominate radiation transport and plasma dynamics. Their spectroscopic signatures provide information on the composition, temperature, density, turbulence, and velocity of plasmas, e. g. those surrounding stars, X-ray binaries, active galactic...
Optical clocks based on highly charged ions (HCIs) offer several promising avenues for the study of physics beyond the standard model. Among these are searches for time variation of the fine structure constant, $\dot{\alpha}/\alpha$, ultralight scalar dark matter, and tests of quantum electrodynamics (QED) [1]. Due to level crossings occurring in high charge states, narrow linewidth...
Motional modes of ions trapped in the same potential are often used to transfer information between ions, for example in quantum logic spectroscopy or Molmer-Sorensen gates. Good motional control is crucial for high-fidelity operations; as many modes as possible should be cooled to near the ground state. Unfortunately, in some crystals, due to geometrical constraints on the apparatus or low...
Quantum technologies employing trapped ion qubits commonly rely on the motional state of the ion. Motional states can not only be used for entanglement operations but also for example to store quantum information or can act as a tool for logic spectroscopy. Hence, a precise knowledge about the motional state of the ion is often required.
In this work we present two novel methods to measure...
Ion traps are a promising platform to host a quantum information processor. However, on the road to producing a functional quantum computer, scaling up to hundreds of ions is a challenge.
The established usage of 1D arrays of ion qubits limits connectivity to low ion numbers, thus restricting the quantum advantage.
In this work we develop an ion trap architecture where independent ion...
When considering the design of a trapped-ion quantum computer, a key aspect that emerges is the required operating temperature. Indeed, several advantages can be gained by operating trapped ion systems at low temperatures [1]. For example, cryogenic ion-trap systems boast of enhanced vacuum conditions, leading to increased ion lifetime; lower motional heating rates, increasing both ion...
Trapped ions are promising qubit systems for quantum information processing due to their long coherence times and high gate fidelities. Current scalable trap design efforts rely on 2D surface traps, which are challenged by shallow trap depths and sensitivity to electric field noise. We built a cryogenic system aimed at efficient, iterative prototyping of scalable 3D-printed ion traps. These...
Trapped ions are a leading platform for quantum computing due to their long coherence time, high level of control over internal and external degrees of freedom, and the natural full connectivity between qubits. Single and multi-qubit operations have been performed with high fidelity (>99.9%), enabling the demonstration of small universal quantum computers (approx. 10 atoms). However, scaling...
Sinara is an open-source, open-hardware control system specifically created for quantum applications that is currently operational in numerous global laboratories. Its design is based on ribbon cable connections linking a controller with peripheral modules. This seemingly uncomplicated and economical method, however, has raised concerns about system reliability, thermal management, and...
Direct implementation of multi-qubit gates with three or more qubits circumvents decomposition into two-qubit operations, effectively reducing the required depth of quantum circuits. Using the inherent all-to-all coupling in a trapped ion quantum computer, we experimentally realize classical Toffoli and perceptron gates with three microwave-driven hyperfine qubits using 171Yb+ ions. The...
We report the numerical simulation, fabrication process, and characterization of a segmented-blade trap with biasing rods [1, 2]. Our homemade trap consists of two radio frequency blades, dc blades with ten separate electrodes, and two biasing rods for compensating the ions' micromotion. We explore the effect of the rods on the trap potential and the influence of trap misalignment. The trap...
Microwave driven operations offer a scalable approach to trapped ion quantum computing, with cheap and reliable components; stable phase and amplitude control; and potentially higher fidelity gates. However, whilst laser beams can be focussed onto individual ions, the centimeter-wavelength of microwaves requires alternate techniques to address individual qubits. Here, we experimentally...
In a recent demonstration of the quantum charge coupled device (QCCD) trapped ion architecture [1], circuit time is dominated by cooling operations. Some motional modes of a multi-ion crystal are cooled inefficiently due to the geometry of the cooling lasers and the coupling of the mode to the sympathetic coolant ion species, requiring as much as 1 ms to cool to the ground state, whereas...
Manipulation of single trapped molecules on the quantum level has gained notable interest in recent years. Their complex energy-level structure with rotational and vibrational degrees of freedom provides a plethora of transitions with various properties but also presents challenges toward molecular state initialisation, manipulation and readout. Building on the methods known for trapped atomic...
Highly charged ions (HCI) offer promising candidate species for searches of physics beyond the Standard Model and next-generation optical atomic clocks. In the CryPTEx-SC experiment, we store HCIs in a cryogenic linear Paul trap that simultaneously functions as a superconducting radio-frequency resonator filtering the trap drive [1].
The HCIs are produced in a compact electron beam ion trap...
Superradiant lasers are a promising path towards realising a narrow-linewidth, high-precision and high-bandwidth active frequency reference [1]. They shift the phase memory from the optical cavity, which is subject to technical and thermal vibration noise, to an ultra-narrow optical atomic transition of an ensemble of cold atoms trapped inside the cavity. Our previous demonstration of pulsed...
The motional degree of freedom of a trapped ion system has been studied as a conveyor of quantum information in the context of continuous variable quantum computing (CVQC) [1,2]. Theoretical and experimental studies concerning quantum information processing with the motional degrees of freedom include phonon sampling [3,4], and encoded qubits [5]. In this work, we experimentally create the...
We present our experimental progress on the control and application of the vibrational modes with a cryogenic trapped Calcium ions system. We implement a segmented four-blade Paul trap in a closed-cycle 4 K cryostat, achieving a heating rate of 8 phonon/s at a trap frequency of 1.1 MHz. We utilize this setup and entangle two vibration modes with reservoir engineering, and obtain a stable...
Detecting and minimizing the micromotion in an ion trap system is crucial for precise control of the quantum states and suppression of heating. For this purpose, several methods have been reported, such as measuring fluorescence amplitude at the rf frequency, optimizing the optical sideband spectrum, minimizing ion displacement while alternating between different trap depths, and employing...
The currently most accurate frequency standards based on optical transitions have reached fractional systematic uncertainties on the order of $1 \times 10^{-18}$, enabling sensitive tests of fundamental physics [1]. The Stark shift induced by room temperature blackbody radiation (BBR) in many cases causes the largest shift from the unperturbed transition frequency and limits the systematic...
Digital quantum simulation is an exciting near-term application of NISQ quantum devices. The re-programmable digital approach allows them to emulate a wide range of interesting materials, such as topological matter or large molecules, that have proven too complex to understand using classical physics and standard computation. Digital simulation combines the tool-set of quantum information with...
Electronic control methods, where quantum gates are implemented without lasers, hold great potential for trapped-ion quantum computing due to their low fundamental errors and the ease of scalability. In this work, we demonstrate a new electronic control method, where addressed single-qubit rotations are implemented by localized AC electric fields, generated by trap electrodes. We demonstrate...
Trapped Rydberg ions combine the advantages of ion trapping and tunable and long-range Rydberg interactions. They enable entangling operations over longer distances and are great candidates for performing fast and scalable entangling gates.
Working with Rydberg ions is promising but also challenging. It is so mostly due to the need to address transitions with UV lasers and relatively frequent...
We present the fabrication of trapped ion microchips integrated with the key features required to realise a scalable architecture for a modular microwave trapped-ion quantum computer. In our approach for ion trap quantum computing [1], high currents of up to 15 A generate large local magnetic field gradients at the ion position which, together with global microwave and RF fields, enable the...
The inherent quantum nature of single trapped ions makes them promising candidates for the experimental realization of qubits, the fundamental building blocks of quantum computers. In order to harvest the potential that trapped ions posses, it is necessary to not only have precise control over an ion's quantum state but also over its motional state. Doppler cooling is commonly deployed to...
Chip-based ion traps are a versatile platform for quantum technologies. Our established ion traps for optical clocks enable controlling systematic frequency uncertainties at the 10^-19 level [1, 2]. Currently, we are developing ion traps with integrated optics. Integrated optics improve the robustness against vibrations, make the traps scalable to large numbers of ions, and help to compactify...
Trapped ions are one of the leading candidates for performing quantum simulation, computation, and precision measurements. Entanglement in simulation experiments plays a crucial role in generating exciting quantum many-body states and distinguishes these experimental systems from their classical counterparts. Investigating entanglement in many body systems is extremely valuable to reveal...
Interference underpins some of the most unusual and impactful properties of both the classical and quantum worlds, from the highest powered lasers down to the level of single photons. However, with regards to light-matter coupling, neither the usual classical nor quantum descriptions of interference can sufficiently explain why some states of light couple to matter while others do not. In this...
Sensors based on the wave nature of a massive particle are expected to be one of the next generations’ high-performance sensing technologies. Atoms and ions are ideal for such use since they give us the capability to control their quantum states using optical means precisely. A Laser-cooled ion in an ion trap is an important platform for quantum sensing due to its ideally isolated condition...
Networked architectures provide a route to freely-scalable quantum computation with trapped ions, with entanglement between ions in remote nodes mediated by the coherent production, interference and projective measurement of single photons. Two-node networks have provided proof-of-principle demonstrations but have been limited in the rate of entanglement achieved, and many further hurdles...
We present our preliminary findings regarding the measurement of the isotope shift in the $4s\textrm{ }^2S_{1/2} \rightarrow 3d\textrm{ }^2D_{5/2}$ transition within pairs of even isotopes of Ca$^+$. We perform the measurement by co-trapping the isotope pairs in a single well produced by a micro-fabricated segmented ion trap. Our method showcases a significant advancement in accuracy,...
Radium-225 (nuclear spin 1/2) is a particularly appealing candidate for optical clocks and testing fundamental symmetries due to its accessible electronic structure and heavy, octupole deformed nucleus. We demonstrated the first laser cooling of short-lived $^{224}$Ra$^+$ (3.6 day half-life) and $^{225}$Ra$^+$ (15 day half-life) ions which are loaded into linear Paul traps by a two-step...
The Antimatter Experiment: Gravity, Interferometry, Spectroscopy (AEGIS) at CERN utilizes cold antiproton beams from the Antimatter Decelerator to study gravitational effects on antihydrogen beams. The pulsed production of Rydberg excited antihydrogen is achieved through a charge exchange reaction between laser-excited Rydberg positronium and cold antiprotons. This same technique is now being...
At the proton g-factor experiment in Mainz we have recently succeeded in sympathetically cooling a single proton by laser-cooled 9Be+ ions stored in a separate Penning trap. Here, the coupling between both ion species is mediated by image currents induced in a common RLC circuit. Uniquely, our setup combines laser cooling and fluorescence detection of the 9Be+ ions with image current detection...
Entangling gates are an essential buliding block of any quantum processor, ideally working at high speeds in a in a robust and scaleable manner. Microwave-driven trapped-ion gates present promising features in terms of scalability and stability of the driving field. Experimentally, limited fidelity values are mostly attributed to the use of magnetic field sensitive states, which make qubits...
Registers of different qubit types, where one qubit type is insensitive to the other's light fields, are a promising avenue for scaling the quantum information processing capabilities of trapped-ion systems [1]. This approach mitigates scattering errors and allows for advanced qubit control schemes by enabling partial projective measurements, mid-circuit measurements, and in-sequence...
Trapped ions are a leading platform for quantum computers, with their high level of programmability and lack of idle decoherence mechanisms. Here, we present progress on building a state-of-the-art quantum computer with full control of up to 32 $^{171}$Yb$^+$ ion qubits on a Sandia Phoenix ion trap chip. We measure the heating rate as a function of trap axial frequency and manage sources of...
We study two parallel ion chains in a surface-electrode trap with an RF electrode configuration creating a double-well potential in order to establish a nanofriction model. One of the nanofriction models is Frenkel-Kontorova (FK) model which has close similarities to two parallel ion chains. The FK model is composed of a chain of classical particles which are harmonically coupled to the...
A system of confined charged particles undergoes crystallization at sufficiently low temperature, forming self-organized structures in which each particle is spatially localized. However, when particles in a two-dimensional plane are confined by an isotropic potential, there is no preferential orientation of the crystal, and thermal fluctuations lead to the delocalization of particles in...
Long chains of trapped ions are a leading platform for quantum information processing, but their control suffers from spectral crowding and excess motional heating when chains grow too long. One proposal to access larger Hilbert spaces and thus more computational power is to entangle ions in separate traps via photonic interconnects. Previous demonstrations have used 0.6 NA objectives to...
Trapped ion chains are a promising architecture for the development of quantum computers and quantum simulators owing to their high connectivity, high-fidelity gate operations, and long coherence times. Scaling up to many qubits is challenging as adding more ions to each chain increases its susceptibility to electric fields, slows down the gate operation and increases errors due to thermal...
While prime candidates as nodes in long-distance quantum networks, trapped ions do not typically emit photons at telecommunications wavelengths. Quantum frequency conversion (QFC) allows trapped ions to connect with other nodes of a long-distance quantum network by frequency downconverting ion-emitted visible and near-IR photons to telecommunications wavelengths [1-3]. Polarization-preserving...
A detector moving with relativistic accelerated trajectory would experience Unruh effect and raise both detector excitation and particle creation in the accelerated frame, despite being in a vacuum in the rest frame. We simulate such an effect in the case of the detector oscillating in a cavity with a laser-controlled trapped ion. The simulation could be extended to superposed quantum...
Ion traps are a promising candidate for a scalable quantum computer [1]. A major challenge is the integration of qubit control into the device.
With the microwave near-field approach [2], qubit control realized by microwave conductors that are integrated into the ion trap naturally scale with the trap itself.
However, the microwave signal generation currently takes place outside of the...
A cornerstone of all quantum technology is the reliable characterization of the underlying building blocks, in particular the prepared quantum states. The standard approach for this task is to perform local Pauli measurements and from that estimate the quantities of interest. As the system size grows, however, the number of measurement bases to consider grows exponentially. We show that this...
Linear strings of trapped ions in radio-frequency traps are a well-established platform for quantum simulation of magnetism. However, linear strings feature some drawbacks, among them difficulties in scaling the system size beyond 50 ions or the inability to investigate spin models in more than one dimension where many exotic quantum phenomena are expected to manifest. Here we present our...
Penning traps are high-precision tools for mass spectrometry and spectroscopy experiments. Two such experiments based on Penning traps at the GSI Helmholtz Centre for Heavy Ion Research are: ARTEMIS and SHIPTRAP. The ARTEMIS Penning trap experiment aims to measure the magnetic moment of an electron bound to heavy, highly charged ions using the laser-microwave double-resonance spectroscopy...
A quantum repeater node is presented based on trapped ions that act as single-photon emitters, quantum memories, and an elementary quantum processor. The node’s ability to establish entanglement across two 25-km-long optical fibers independently, then to swap that entanglement efficiently to extend it over both fibers, is demonstrated. The resultant entanglement is established between...
Quantum simulations stand out as a particularly promising application of quantum computers. The noisy intermediate-scale quantum (NISQ) devices pave the way for the development of fault-tolerant quantum computers. However, the presence of noise and decoherence in current noisy quantum devices necessitates the use of hybrid quantum algorithms based on low-depth circuits to achieve promising...
The NEXT experiment [1] is currently being built at the AGOR facility in Groningen. NEXT aims to study Neutron-rich EXotic, heavy nuclei around N=126 and in the transfermium region which are produced in multinucleon Transfer reactions. Precision mass spectrometry and decay spectroscopy will be used to characterize these nuclei.
The target-like transfer products are pre-separated from the...
The success of trapped molecular ion precision spectroscopy in eEDM searches motivates the extension of the platform to more complicated polyatomic species to test the Standard Model (SM) and search for new physics.
The prediction that weak force parity violation (PV) breaks the symmetry between the left and right-handed chiral molecules has eluded detection for decades in a field dominated...
Here, we report on the development of a large-scale quantum simulator with programmable individual control of more than 50 $^{171}\rm{Yb}^+\;$ ions in a segmented `blade trap’ system. The trap allows high NA optical access from four directions and will include high fidelity and low crosstalk in-situ state measurement and reset of individual ions [1]. Our custom monolithic optical breadboards...
We report our plans and progress towards implementing a cavity quantum electrodynamics system with Barium ions. With Barium ions’ strong S-P dipole transition at 493 nm, we can expect much stronger ion-cavity coupling than achievable with infrared transitions in Barium as well as in other atomic species. This can be exploited for high-fidelity light-atom entanglement generation and state...
Comparisons of fundamental properties of matter and antimatter provide stringent tests of CPT symmetry [1]. Throughout the past years, measurements of proton and antiproton g-factors in Penning traps have been carried out with outstanding precision, setting new constraints on CPT violating effects of the SME [2,3]. However, these experiments rely on time consuming particle cooling and state...
Large scale quantum computing is subject to extensive research and the ideal platform for general purpose quantum computers has yet to be found. Trapped ions as qubits excel in terms of gate fidelity and coherence times but so far systems have mostly been limited to only a small number of qubits. Our system is designed to support a linear chain of up to 50 ions which can be individually...
Highly charged ions (HCI) feature an enhanced sensitivity to fundamental physics while many systematic effects from external perturbations are highly suppressed [1]. They are therefore excellent systems to test our understanding of nature and to realize novel high-accuracy optical atomic clocks.
Recently, quantum logic spectroscopy (QLS) of a fine-structure transition in a medium-light HCI...
Exotic atoms, formed by substituting one or more of their constituents—electrons, protons or neutrons—with others of the same electric charge, have played a pivotal role in studying the fundamental interactions in nature. Antiprotonic exotic atoms, containing at the same time matter and antimatter can be used to test matter-antimatter asymmetries, one of the unresolved questions in modern...
Singly ionized lutetium ($^{176}$Lu$^+$) has a unique level structure that provides multiple clock transitions. In combination with hyperfine averaging, two of these transitions ($^1{S}_0$ – ${}^3D_1$ & $^1{S}_0$ – ${}^3D_2$) present both a long lifetime and low sensitivity to the electromagnetic environment, which allows high performance clock operation on both transitions. Recently we have...
Here our progress on the Ca+ ion optical clocks for the last few years will be reported, including both the laboratory clocks and the transportable clock.
A cryogenic Ca+ clock at the liquid nitrogen environment is built, with the blackbody radiation (BBR) shift uncertainty greatly suppressed, and improvements made with other systematic uncertainties, the overall systematic uncertainty of...
Optical clocks based on mixed-species Coulomb crystals promise reductions of both statistical and systematic uncertainties beyond the state of the art.
We operate an optical clock based on the combination of ${}^{115}$In${}^+$ (clock) and ${}^{172}$Yb${}^+$ (auxiliary) ions, which we have identified as a candidate for multi-clock-ion operation with $10^{-19}$ level systematic uncertainties...
Visible light photonic integration will enable compact, low weight, and reliable quantum and atomic sensing systems. In this talk we will review the latest advances in the ultra-low loss silicon nitride integration platform and heterogeneous integration, that enable quantum systems on chip (QSOC). Various technologies supported include visible light and ultra-narrow linewidth lasers, ...
The energy levels of hydrogen-like atoms can be precisely described by bound-state quantum
electrodynamics (QED). The frequency of the narrow 1s-2s transition of atomic hydrogen has
been measured with a relative uncertainty below $10^{−14}$. When combined with other spectroscopic
measurements of hydrogen and hydrogen-like atoms, the Rydberg constant and the proton charge
radius can be...
The antiProton Unstable Matter Annihilation (PUMA) experiment is a nuclear physics experiment at CERN which will determine the ratio of protons to neutrons in the nuclear density tail based on the peripheral annihilation of low-energy antiprotons, providing a new observable to test nuclear structure theory. As the annihilation conserves the total charge, the annihilated nucleon can be...
Quantum computers hold the promise to efficiently solve some computationally hard, classically intractable problems. Unfortunately, unavoidable noise limits the capabilities of current noisy intermediate-scale quantum (NISQ) devices. In my talk, I will first introduce basic concepts of topological quantum error correcting codes and quantum fault-tolerance, which is imperative to prevent errors...
Quantum computation at scale requires methods to address the accumulation of errors. Fault-tolerant quantum computing building on top of (i) sufficiently small error rates, (ii) suitable encoding of quantum information across multiple qubits, and (iii) carefully chosen interactions to limit error propagation, allow one to increase the system size without increasing the error rates in the...
One of the main challenges facing large-scale quantum computing is scaling systems to more qubits while maintaining high fidelity operations. In this talk, I will describe our efforts at Quantinuum in scaling trapped-ion quantum computers based on the quantum charge-coupled device architecture. We recently released our second-generation machine, which has a race-track shaped ion trap. The...
I will describe experimental work on the control of ions in a micro fabricated surface-electrode Penning trap. The work is motivated by the possibility to realise micro-trap arrays for quantum computing, sensing and simulation, without being restricted by the complications introduced by high-voltage RF fields for trapping. At a trapping height of 152 micron, we have trapped beryllium ions and...
Bosonic codes comprise a paradigm for quantum computing and quantum error correction where quantum information is encoded in continuous degrees of freedom such as modes of radiation or motion. In particular, Gottesman-Kitaev-Preskill (GKP) codes [1] are promising candidates for bosonic quantum information processing, in which quantum error correction has recently been demonstrated both in...
Trapped-ion quantum technology is one of the most promising candidates for the realization of scalable quantum processors. To address individual ions and perform high-fidelity two-qubit entangling gates in a linear segmented Paul trap, we dynamically employ register reconfiguration operations to place specific qubits in a laser interaction zone in combination with addressing of sub registers....
We are developing optical clocks based on radium. Though unstable it has potential for low instability clocks as radium's high mass reduces sensitivity to leading systematic uncertainties. The wavelengths needed for a radium clock are in relatively photonic technology friendly parts of the spectrum, making it appealing for a robust and compact optical clock. The nuclear instability is an...
A hybrid system combining ultracold atoms and ions can be a valuable tool for studying the properties of atom-ion collisions in the ultracold regime. In free space, atoms and ions cannot be bound in an elastic binary collision due to energy and momentum conservation. However, since the ion is strongly trapped, the trap can couple the center-of-mass and relative motion and lead to a short-lived...
Precision measurements of time-reversal (T) symmetry violation in molecular systems provide stringent tests of new physics beyond the Standard Model. Recent measurements of the electron’s electric dipole moment (eEDM) in both neutral molecules [1] and molecular ions [2] have excluded a broad parameter space of T-violating leptonic physics at energy scales up to ~10 TeV. To improve the...
Quantum tunneling reactions play an important role in chemistry when classical pathways are energetically forbidden [1]. Binary collisions of atomic with molecular hydrogen belong to the most fundamental molecular systems and are simple enough to be theoretically investigated using first-principle calculations. The rate of the tunneling reaction H$_2$ + D$^- \rightarrow$ H$^-$ + HD has been...
Previously we have carried out Doppler-free laser vibrational spectroscopy of trapped, laser-cooled $\text{HD}^+$ molecular ions with a relative uncertainty of a few parts per trillion (ppt) [1]. Combined with accurate theoretical predictions and other recent precision measurements, our $\text{HD}^+$ data can potentially improve the literature value of the electron’s relative atomic mass from...
In a special class of ion traps, referred as isochronous traps, stored ions make oscillations with their frequencies independent of orbital parameters such as injection energy, coordinates, and angles. A well-known example of an isochronous ion trap is an ion cyclotron resonance (ICR) cell that utilizes the property of a constant frequency of Larmor precession in a uniform magnetic field. The...
The molecular hydrogen ion $\mathrm{H}_{2}^{+}$ is the simplest molecule. This iconic system has been the subject of innumerous theoretical studies, from the earliest days of quantum mechanics [1] until today, culminating in highly precise predictions of its level energies [2]. Comparisons of these predictions and measured vibrational transition frequencies would offer excellent opportunities...
ALPHA works with trapped antihydrogen atoms to investigate some of its properties and compare it to its matter counterpart, hydrogen. These atoms are created by slowly mixing antiprotons and positrons in one of our Penning-Malmberg traps. There is strong evidence that positron temperature before mixing greatly influences the number of trappable antihydrogen atoms. [1]
Using laser ablation,...
An amazing level of quantum control is routinely reached in modern experiments with atoms, but similar control over molecules has been an elusive goal. A method based on quantum logic spectroscopy [1] can address this challenge for a wide class of molecular ions [2,3]. We have now realized many basic aspects of this proposal.
In our demonstrations, we trap a calcium ion together with a...
We demonstrate a novel single molecule action-spectroscopy technique that is compatible with high precision measurement. The method is generally applicable to a wide range of polyatomic molecular ions, and promises spectral resolution comparable to state of the art quantum logic methods, with significantly less stringent experimental overhead. The method is an extension of the recent...
Modern space and Earth-based telescopes like JWST and ALMA are able to provide us with increasingly detailed insight into the molecular composition of interstellar space. These instruments are able to identify the different species and determine their abundance. However, information on the processes of formation and destruction of molecules in this environment is still needed. Laboratory...
Experiments with single ions confined in a Penning trap enable access to a broad range of observables that are of fundamental importance for our understanding of fundamental physics. In the magnetic field of the trap, the cyclotron frequency of an ion can be determined with unique precision and gives direct access to the charge-to-mass ratio. Furthermore, we have access to the gyromagnetic...
Polar molecular ions in extreme charge states have the potential to merge advantages that highly-charged atomic ions and neutral polar molecules offer, when performing precision tests of fundamental physics. As we have discussed in Ref. 1, one can expect to benefit from enhanced relativistic effects and compressed level structures on the one hand and large internal fields with considerable...
We recently placed a new limit on parity-violating physics with a unique tabletop experiment which combines trapped molecular ions,
rotating bias fields, orientation-resolved detection, and over a dozen lasers. In this talk I will give an overview of our measurement and methods for probing new physics at energy scales exceeding the reach of the LHC.
HITRAP is a facility for deceleration of large bunches of highly charged ions (HCI) produced online by the GSI accelerator. It consists of an ion transport beamline from the accelerator, an IH-structure and an RFQ for deceleration down to several keV/q, as well as a Penning-Malmberg trap for ion cooling down to sub-eV energies.
The linear deceleration stages reduce the ion energy from $4...
Electron-atom collision experiments are widely used to study the structure of bombarded objects. The experimentally determined scattering amplitudes associated with measured cross-sections complement the data obtained in spectroscopic studies. The measurement usually involves the bombardment of the target with a monochromatic electron beam and the detection of non-scattered or scattered...
To realize a useful quantum computer based on trapped ions, scaling the number of ions is an important requirement. However, scaling up to several hundreds or thousands of ions while maintaining sufficient qubit fidelity implies complex trap designs that can only be achieved by first-class industrial manufacturing. Fabrication in a productive fab offers a precise process control as well as...
Modern trapped-ion experiments frequently utilize hundred(s) of trap electrodes and ten(s) of laser beams which have to be operated in a precise and synchronous manner. Akkodis is developing the required control electronic system. Within the IQUAN project [1] we design a modular, scalable electronic system consisting of precision pulse generators and real-time control logic. Within the ATIQ...
In order to scale trapped ion quantum computing from small lab experiments to industrial quantum computers, large ion traps will need to contain integrated electronics. Integrated electronics minimizes the number of voltages passed into the cryostat as the number of feed-throughs is limited. This reduces the complexity as well as the heat load on the cryostat. Here, I want to present the...
Trapped ion crystals consisting of many individual photon emitters offer an ideal platform for the exploration of a wide range of fundamental quantum emission scenarios. We present the implementation of a new optical emission regime in which photons scattered incoherently from different ions collectively contribute to the observation of photon bunching and super-Poissonian photon number...
