The GBAR (Gravitational Behavior of Antihydrogen at Rest) experiment, located at CERNโs AD/ELENA โAntimatter factory,โ aims at measuring the free-fall of antihydrogen atoms to test the Equivalence Principle of General Relativity. Unlike other experiments producing antihydrogen, GBAR uses an in-flight charge-exchange reaction of antiprotons with a cloud of positronium...
Atoms and ions confined with electric and optical fields form the basis of many current quantum simulation and computing platforms. When excited to high-lying Rydberg states, long-ranged dipole interactions emerge which strongly couple the electronic and vibrational degrees of freedom through state-dependent forces. This vibronic coupling and the ensuing hybridization of internal and external...
One of the most attractive quantum computing platforms is that of atomic ions. We aim to investigate an alternative approach that substitutes atomic ions with molecular ions, which allows for the utilization of rotational degrees of freedom for quantum information encoding. However, due to the complex internal structure of molecules, advanced methods are required to manipulate and readout...
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...
The $^{229}$Th nucleus has the unique property of a very low-lying isomeric first excited state with an excitation energy of only 8.338(24) eV [1], which is addressable with state-of-the-art VUV frequency comb laser systems. Storage in the isolated environment of a cryogenic ion trap will allow for lifetime measurements of the excited isomeric state (expected in the range of a few 10$^3$...
Over the past few decades, advancements in optical atomic clocks have made it possible to measure time and frequency with unprecedented stability and systematic uncertainty [1,2]. Precision frequency comparisons between macroscopically separated clocks have applications in geodesy [3], probing variations in fundamental constants, and in dark matter searches [4].
Until now, most previous...
Current ion trap quantum computing systems usually make use of free-space optics to deliver the light to the ions. This practice makes the setups susceptible to drifts and vibrations and limits the number of ions which can be manipulated. For a scalable system it is thus necessary to increasingly integrate optical elements from external components directly into the ion trap. We use...
In trapped-ion quantum computing, the loading of ions from an oven or an ablation target into a trap releases large numbers of hot atoms into the vacuum chamber, affecting vacuum pressure and depositing on surfaces. Furthermore, the challenge of scalability of quantum computers has led to replacing 4-rod Paul traps by surface traps with a lower depth, making in harder to trap hot ions. The...
We report on a method to interface the quantum state of each individual trapped-ion qubit in a register with a separate direction-switchable travelling photon. By switching the ion-trap confinement, ions are brought one at a time into the focus of an optical cavity and emit a photon via a cavity-mediated Raman transition. The result is a train of photons, each entangled with a different ion in...
The PENTATRAP experiment at the Max Planck Institute for Nuclear Physics in Heidelberg is a high-precision Penning-trap mass spectrometer that utilizes a cryogenic environment, a stable magnet, and an image current detection system to determine mass ratios of stable and long-lived highly charged ions with relative uncertainties in the few parts per trillion regime. The data acquired by this...
At the University of Sussex we are developing a novel planar Penning trap technology. We are particularly focused on the applications of trapped electrons in quantum technology, specifically as a quantum microwave transducer. The potential applications span across various domains, including fundamental physics measurements, such as determining the neutrino mass, and technologies such as...
The muCool project aims to develop an innovative device for generating low-energy, high-intensity, and high-quality muon beams for future high-precision experiments such as muon g-2 measurements, muonium spectroscopy, and muonium gravity studies. These experiments, involving muons and muonium atoms, hold significant potential for testing theoretical predictions of the Standard Model within a...
The National Quantum Computing Centreโs Trapped Ion hardware team will host a variety of experimental architectures including different trap types, gate types, and atomic species. Initial internal work has been housing surface traps capable of high-fidelity, high-speed microwave gates in cryostats with a focus on modularity and autonomy for the laser and vacuum subsystems. These traps need to...
The ASACUSA collaboration at CERN plans to measure the ground-state hyperfine structure of a beam of antihydrogen to test CPT. To produce antihydrogen we slowly merged a positron and an antiproton plasma in a Penning-Malmberg trap with a cusped magnetic field. This โsmergeโ method was pioneered by the ALPHA collaboration. We adjusted the rate at which the potential wells were merged from 0.1 s...
High-fidelity gates in trapped Calcium ions rely heavily on the stability of the main 729 nm qubit-manipulation laser, often achieved through locking it to a high-finesse cavity. The quality of the feedback loop governing this lock directly influences the noise of the laser that goes to the ions. This work focuses on presenting and characterizing the performance of a high-bandwidth...
Trapped ions have shown great promise as a platform for quantum computing, with long coherence time, high fidelity quantum logic gates, and the successful implementation of quantum algorithms. However, to develop trapped-ion based quantum computers from laboratory setups to practical devices for solving real-world problems, the number of controllable qubits must be increased while improving...
When scaling up ion trap quantum processors the wiring of the large number of necessary control signals becomes a problem.
We present a concept for reducing the amount of control signals needed for the transport through the X-junction of a surface electrode ion trap. By using switching electronics, the signals are multiplexed and enable the control of multiple electrodes per incoming signal...
Quantum computers are inherently susceptible to the impact of noise. Precise characterization and effective noise mitigation techniques are imperative to progressively overcome the limitations posed by a noisy system such as enabling large-scale quantum computing. Motivated by this necessity, we introduce a newly developed microscopic model designed to provide a more compact parametrization...
A Gabor lens, a type of plasma lens, utilizes the internal electric field of a trapped electron plasma to focus high energy positively charged particles, such as protons or ions [1]. This lens is formed within a non-neutral plasma confined by magnetic and electric fields in a Penning-Malmberg trap [2]. Compared to traditional magnetic lenses, Gabor lenses offer the potential for highly...
Trapped ions in radio-frequency Paul traps are one of the leading candidates for precision metrology at optical frequencies [1]. Ions can be confined and laser-cooled to their motional ground state [2], which minimizes the systematic shifts in the transition spectra. Current engineering challenges call for traps that improve the isolation of trapped ions from the environment and reach...
We present a setup based on a phase spatial light modulator for manipulating the spatial characteristics of spontaneous emission of trapped ions. We delineate three specific applications where our setup demonstrates superior performance compared to current state-of-the-art solutions. Anticipated benefits include the potential to entangle more than two ions through a single photon detection...
Radiofrequency (RF) junctions enable two-dimensional structures within the QCCD architecture and are thus essential for scaling trapped-ion quantum processors. We discuss the design and optimization of RF junctions, highlighting implications for efficient through-junction ion transport. Further, we present an optimized RF junction in a surface-electrode trap and analyze its robustness...
Trapped ions are one of the leading platforms for quantum networks. They benefit from long coherence times, high-fidelity state preparation, readout and gate operations. However, the number of ions that can be well-controlled in any individual trap is very limited. To circumvent this limitation ions can be distributed among many smaller traps that are connected via photonic links [1]. In this...
Surface electrode ion traps are well suited for building a scalable quantum computer because ions trapped in a Paul trap can have long coherence times combined with high fidelities, and it is possible to move the qubits around in a 2-D surface. I will present our design for a cryogenic setup aimed at increasing the fidelity of state preparation and quantum gates. Our experiments allow us to...
Trapped ions are interesting in the field of quantum computing due to their exceptional qubit coherence times and high-fidelity gate operations. An imaging system is central to their functionality, as it plays a critical role in visualizing, understanding, and troubleshooting the workings of the ion trap. We design one such imaging system while keeping in mind the challenges that arise while...
A high priority in the worldwide search for 'New Physics' involves testing violations of fundamental symmetries. In particular, one the largest remaining cosmological questions is why the observable universe is populated by only matter, rather than equal amounts of matter and antimatter. By comparing the results of precise laser spectroscopy of both matter and antimatter, CPT symmetry can be...
Trapped ion quantum computers are transitioning from hands-on experiments to highavailability production systems. To achieve this, it is crucial to attain and maintain high operational fidelities of the quibt operations. Regular recalibration of system parameters is necessary due to the influence of fluctuating environmental factors. So far, this has been a labor-intensive and time-consuming...
While Paul traps are commonly used in ion trapping, electron trapping with Paul traps is a new line of advance, done only by few laboratories in the world [1โ2]. It requires comparably high (GHz range) frequency, which creates a challenge for efficient power supply. Low input power, decreasing device heating, can be achieved by designing the trap as part of a resonator. We have developed a...
An approach to overcome the obstacles of scalability of quantum computers is to use d-level (d>2) quantum systems, known as qudits which are inherently present in most quantum computing platforms. While qudits provide significant additional computational resources, the underlying theory on constructing qudit computational primitives and their experimental implementation remain widely...
Performing quantum spectroscopy on a single trapped $^{138}\mathrm{Ba}^{+}$ ion to determine D$_{5/2} - $P$_{3/2}$ transition frequency. A single isotope selected ions was loaded into a cryogenically cooled linear Paul trap which is subjected to a stable magnetic field. With an ion in the ground state, a narrow 1762 nm fiber laser was employed to address the quadrupole S$_{1/2} - $D$_{5/2}$...
Recently, using Rydberg-states for gate operation in trapped ions has been shown to greatly reduce two qubit gate times down to 700ns [1]. Those experiments were performed in a macroscopic Paul trap at room temperature. We propose to perform similar experiments but in a cryogenic environment as well as on a of surface ion trap chip that is industrially microfabricated at Infineon Technologies...
Trapped ions provide a promising platform for building a Europe-wide quantum internet where quantum network nodes are separated by several hundreds of kilometres. Coherent ion-photon interfaces, consisting of a linear Paul trap with an integrated cavity, exist for more than a decade [1], and are capable to act as a quantum processor, telecom-wavelength quantum repeater [2] and quantum memory...
Trapped-ion quantum systems are promising candidates for future quantum computing applications. Further advancements in scalability, reliability, and improved gate fidelity are of utmost importance. In the ATIQ consortium, we enhance our cryogenic apparatus design by transitioning to 43Ca+ as our logical qubit ion. This shift will pave the way for integrating waveguides into our existing trap...
Building a useful fault tolerant quantum computer requires precise and coherent control over several thousands of qubits. While the trapped ion platform has demonstrated such control over a limited number of ions, scaling to larger qubit numbers requires microfabricated trap chips characterized by a high degree of integration and process stability which can usually only be achieved within...
Trapped molecular systems are excellent tools for precise quantum control, offering a wide range of applications in quantum computing, precision spectroscopy, tests of fundamental physics and state-to-state chemistry [1,2]. However, these systems have complex internal energy-level structures and in addition, they lack readily accessible closed cycling transitions which makes their state...
One of the obstacles in scaling up trapped ion quantum computing is the increasing number of free-space lasers with increasing numbers of ions. These lasers are necessary forย cooling the ions as well as performing quantum state manipulation and readout. In QCCD architectures, where ions are moved in two-dimensional trap arrays, individual addressing by free-space lasers further increases the...
In experiments with trapped ions, individual particles are separated due to the Coulomb force. This feature makes the system especially suitable for studying few-body systems. In contrast, a large number of neutral atoms can reach quantum degeneracy. In our laboratory, we are developing a hybrid system of trapped Barium ions and neutral Lithium atoms. In our previous work, we have investigated...
In quantum information processing, the controlled and isolated environment provided by cold trapped ions is pivotal for extending coherence times and reducing error rates, thus advancing the capabilities of quantum computing. We use two calcium ions in a string confined in a radio-frequency trap and prepared in their ground state of motion (with motional quantum number close to zero) using the...
Extensive research is dedicated to large-scale quantum computing, still which one optimal platform is superior for general-purpose quantum computers is not yet clear. Trapped ions, serving as qubits, demonstrate superior gate fidelity and coherence times. However, current systems predominantly operate with a limited number of qubits. We are working to construct a new design that supports a...
Molecular ions offer more degrees of freedom than atomic ions. These larger Hilbert spaces are rich and interesting landscapes to explore, possibly enabling quantum information applications such as quantum error correcting (QEC) schemes not available in atomic ions. This requires efficient and precise control of the molecular ion states. Co-trapping a molecular ion with an atomic ion...
We investigate scalable ion trap architectures for quantum computing and simulation, where independent ion strings are located in distinct lattice sites (or potential wells) in a 2D array of RF traps. Distinct ion strings are coupled via their dipole-dipole interaction. Full 2D connectivity is achieved tuning the distance between adjacent potential wells along two orthogonal directions: One...
Periodically driven quantum systems in a thermal environment generically settle to a Floquet-Gibbs state in a rotating frame, which is stable on long-time scales, provided that the driving frequency is high enough. However, in laser-driven atomic systems, which is a versatile platform for quantum technologies, the situation is typically more complicated, since the corresponding Hamiltonian is...
At the forefront of precise time measurement, atomic clocks stand as essential tools, offering unparalleled accuracy crucial for a multitude of applications in radio astronomy, navigation systems, telecommunications and scientific research. The aim of this project is to develop a laboratory-scale atomic clock based on a Rubidium gas cell, which is exposed to microwave radiation and illuminated...
T. Maddock, S. Kulmiya, S.J. Hile, D.S. Smith, S. Weidt & W. K. Hensinger
Sussex Centre for Quantum Technologies
University of Sussex
Brighton
BN1 9QH, UK
The ability to generate and distribute entanglement in open quantum systems is a prerequisite for a fully-fledged quantum computer. The former of which, within this group, has been achieved typically using geometric phase...
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...
We realize a universal gate-set for quantum computing with microwave nearfields
with trapped ions [1]. $^9Be^+$ ions are trapped in a surface electrode trap with
an integrated microwave electrode. Single ion addressing is done through micromotion
sidebands [2]. We approach entangling infidelity of $10^{-3}$ with Mรธlmer-Sรธrensen
gates. Based on the work done by [3] we investigate further...
Laser-cooled trapped ions platform is one of the best candidates for the development of future quantum computing. This has generated a major worldwide research effort aimed at scaling and integrating trapping devices. As part of this effort, we are developing miniature atomic ion traps in the laboratory: Paul linear surface traps manufactured in collaboration with Nanyang Technology University...
The investigation of nuclear ground-state properties of short-lived radioactive isotopes through laser spectroscopy is an important probe of state-of-the-art nuclear-structure theories. This field has mainly been driven by Collinear Laser Spectroscopy (CLS) and Resonant Ionization Spectroscopy (RIS) in the last decades. In both techniques, the laser spectroscopy is performed in-flight which...
Multi-species trapped ion quantum computing offers a promising solution to challenges around ground state cooling, optical crosstalk, and provides a natural separation between operations with contradictory requirements, particularly as the number of ions in a device is increased. We show work towards the implementation of a small logical qubit using Ytterbium (Yb) and Barium (Ba) ions in an...
The integration of photonic components in surface electrode traps is a novel and impactful technology, representing a promising approach for scalable quantum computing with trapped ions [[Mehta2023]][1].
In this architecture, photonic waveguides are embedded in a trap layer underneath the electrodes to route light with high efficiency to the position of interest. Integrated gratings output...
Trapped ions coupled to an optical cavity have proven to be good candidates for atomโphoton interface, which provide a basis for quantum network applications. Increasing coupling strength between the cavity and ions remains a central focus for advancements of the ion-cavity systems.Promising approach involves the usage of microcavities fabricated on optical fibers.In this poster an existing...
Trapped-ion qubits are a promising hardware platform for quantum computing and quantum simulation. In our experiment, the qubits are encoded in two hyperfine levels of $^9$Be$^+$ ions confined in a cryogenic surface-electrode Paul trap. By integrating microwave conductors into the trap, we can generate an oscillating magnetic field and gradient at the ionโs position which can drive carrier and...
In order to scale current hardware for trapped ion Quantum computers, it is imperative to go from the widely used one dimensional schemes (linear traps) to bi-dimensional schemes. A straightforward starting point is to implement arrays of linear traps, but they need to be efficiently connected between each other. Those interception points are called junctions, and can be X, Y or T junctions...
Vibrational transitions in molecules are sensitive to changes in the proton-to-electron mass ratio. In this experiment, we are using spectroscopy in a nitrogen ion clock to search for dark matter and possible time variations in the proton-to-electron mass ratio. For this, we will probe the v=0 to v=2 vibrational transition in nitrogen and look for changes in the frequency over time.
The...
The GBAR experiment aims to measure the gravitational acceleration of antihydrogen atoms within a terrestrial gravitational field. In this experiment, antihydrogen atoms are produced by the interaction of a positronium cloud with an antiproton beam. A Penning-Malmberg trap has been developed to capture antiprotons supplied by ELENA at CERN, enabling the generation of a high-intensity...
Even though the standard model has been successful in predicting and describing subatomic phenomena, it requires symmetry under charge, particle and time inversion and can thus not explain certain cosmological observations. A difference in the fundamental properties between matter and antimatter would break CPT invariance, will further our understanding of the shortcomings of the standard...
The reason why there is no primordial antimatter in the Universe remains a mystery. Measurements with antimatter [1][2] show full compatibility with its matter counterparts at high precision and that the antimatter feels Earth's gravitational attraction similarly to matter [3] at low precision.
Antihydrogen (Hbar) is produced by trapping antiprotons and positrons in neighboring wells in a...
Quantum sensing is a promising application of quantum technologies. The aim is to exploit the quantum nature of sensors to provide an increase in sensitivity of precision measurements. With several demonstrations of elementary quantum networks, e.g. [1, 2, 3], a natural question is whether distributed quantum sensors can provide an advantage for sensing fields with arbitrary spatial profiles....
