Table-top Setups Research Articles

What ultracold atoms tell us about the real-time dynamics of QCD in extreme conditions

I review developments of how compact table-top setups with ultracold atoms can help us to understand the more complex real-time dynamics of QCD probed in heavy-ion collision experiments.

Engineering a U(1) lattice gauge theory in classical electric circuits

Lattice gauge theories are fundamental to such distinct fields as particle physics, condensed matter, and quantum information science. Their local symmetries enforce the charge conservation observed in the laws of physics. Impressive experimental progress has demonstrated that they can be engineered in table-top experiments using synthetic quantum systems. However, the challenges posed by the scalability of such lattice gauge simulators are pressing, thereby making the exploration of different experimental setups desirable. Here, we realize a U(1) lattice gauge theory with five matter sites and four gauge links in classical electric circuits employing nonlinear elements connecting LC oscillators. This allows for probing previously inaccessible spectral and transport properties in a multisite system. We directly observe Gauss's law, known from electrodynamics, and the emergence of long-range interactions between massive particles in full agreement with theoretical predictions. Our paper paves the way for investigations of increasingly complex gauge theories on table-top classical setups, and demonstrates the precise control of nonlinear effects within metamaterial devices.

Design of a Scalable Integrated Nanophotonic Electron Accelerator on a Chip

A simple way of implementing a scalable laser-driven nanophotonic electron accelerator on a chip is presented. The design requires only a single incident laser pulse and can be fabricated straightforwardly on commercial silicon-on-insulator wafers. We investigate the low-energy regime of tabletop electron microscopes where the silicon structures safely allow peak gradients of about 150 MeV/m. By means of a three-dimensional alternating-phase-focusing scheme, we obtain about half of the peak gradient as the average gradient with six-dimensional confinement and full-length scalability. The structures are completely designed within the device layer of the wafer and can be arranged in stages. We choose the stages as energy doublers and outline how errors in the handshake between the stages can be corrected by on-chip steerers. Since the electron pulse length in the attosecond realm is preserved, our chip is the ideal energy booster for ultrafast-electron-diffraction machines, opening the megaelectronvolt scale on tabletop setups.

Fast, High-Quality Two-Arm Rearrangement in Synchronous, Monotone Tabletop Setups

Rearranging objects on a planar surface arises in a variety of robotic applications, such as product packaging. Using two arms can improve efficiency but introduces new computational challenges. This article studies the problem structure of object rearrangement using two arms in synchronous, monotone tabletop setups and develops an optimal mixed-integer model. It then describes an efficient and scalable algorithm, which first minimizes the cost of object transfers and then moves between objects. This is motivated by the fact that, asymptotically, object transfers dominate the cost of solutions. Moreover, a lazy strategy minimizes the number of motion planning calls and results in significant speedups. Theoretical arguments support the benefits of using two arms and indicate that synchronous execution, in which the two arms perform together either transfers or moves, introduces only a small overhead. Experiments support these claims and show that the scalable method can quickly compute solutions close to the optimal for the considered setup. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —Monotone tabletop rearrangement challenges arise in a variety of automation scenarios, including product sorting or packing. Performing this task with two robotic manipulators introduces the overhead of coordinating them in the shared workspace, as well as an increase in the size of the underling search space. The objective of this work is to study the feasibility of such dual-arm solutions, providing both theoretical bounds, as well as a fast, and approximate solution. The approach leverages an effective algorithmic decomposition of the problem so as to take advantage of efficient motion planners and mixed-integer linear programming solvers. The proposed solution has been evaluated in settings that include delta robots as well as seven-degree-of-freedom (DOF) manipulators. Interesting extensions of this work correspond to studying the case of additional arms, nonmonotone, and general manipulation scenarios.

An open-source, end-to-end workflow for multidimensional photoemission spectroscopy

Characterization of the electronic band structure of solid state materials is routinely performed using photoemission spectroscopy. Recent advancements in short-wavelength light sources and electron detectors give rise to multidimensional photoemission spectroscopy, allowing parallel measurements of the electron spectral function simultaneously in energy, two momentum components and additional physical parameters with single-event detection capability. Efficient processing of the photoelectron event streams at a rate of up to tens of megabytes per second will enable rapid band mapping for materials characterization. We describe an open-source workflow that allows user interaction with billion-count single-electron events in photoemission band mapping experiments, compatible with beamlines at 3rd and 4rd generation light sources and table-top laser-based setups. The workflow offers an end-to-end recipe from distributed operations on single-event data to structured formats for downstream scientific tasks and storage to materials science database integration. Both the workflow and processed data can be archived for reuse, providing the infrastructure for documenting the provenance and lineage of photoemission data for future high-throughput experiments.

Versatile Photonic Entanglement Synthesizer in the Spatial Domain

Multimode entanglement is an essential resource for quantum information in continuous-variable systems. Light-based quantum technologies will arguably not be built upon table-top bulk setups, but will presumably rather resort to integrated optics. Sequential bulk optics-like proposals based on cascaded integrated interferometers are not scalable with the current state-of-the-art low-loss materials used for continuous variables. We analyze the multimode continuous-variable entanglement capabilities of a compact currently-available integrated device without bulk-optics analog: the array of nonlinear waveguides. We theoretically demonstrate that this simple and compact structure, together with a reconfigurable input pump distribution and multimode coherent detection of the output modes, is a versatile entanglement synthesizer in the spatial domain. We exhibit this versatility through analytical and numerically optimized multimode squeezing, entanglement, and cluster state generation in different encodings. Our results re-establish spatial encoding as a contender in the game of continuous-variable quantum information processing.

Mixed Reality Tabletop Gameplay: Social Interaction With a Virtual Human Capable of Physical Influence.

In this article, we investigate the effects of the physical influence of a virtual human (VH) in the context of face-to-face interaction in a mixed reality environment. In Experiment 1, participants played a tabletop game with a VH, in which each player takes a turn and moves their own token along the designated spots on the shared table. We compared two conditions as follows: the VH in the virtual condition moves a virtual token that can only be seen through augmented reality (AR) glasses, while the VH in the physical condition moves a physical token as the participants do; therefore the VH's token can be seen even in the periphery of the AR glasses. For the physical condition, we designed an actuator system underneath the table. The actuator moves a magnet under the table which then moves the VH's physical token over the surface of the table. Our results indicate that participants felt higher co-presence with the VH in the physical condition, and participants assessed the VH as a more physical entity compared to the VH in the virtual condition. We further observed transference effects when participants attributed the VH's ability to move physical objects to other elements in the real world. Also, the VH's physical influence improved participants' overall experience with the VH. In Experiment 2, we further looked into the question how the physical-virtual latency in movements affected the perceived plausibility of the VH's interaction with the real world. Our results indicate that a slight temporal difference between the physical token reacting to the virtual hand's movement increased the perceived realism and causality of the mixed reality interaction. We discuss potential explanations for the findings and implications for future shared mixed reality tabletop setups.

Atomic and Molecular Processes in a Strong Bicircular Laser Field

With the development of intense femtosecond laser sources it has become possible to study atomic and molecular processes on their own subfemtosecond time scale. Table-top setups are available that generate intense coherent radiation in the extreme ultraviolet and soft-X-ray regime which have various applications in strong-field physics and attoscience. More recently, the emphasis is moving from the generation of linearly polarized pulses using a linearly polarized driving field to the generation of more complicated elliptically polarized polychromatic ultrashort pulses. The transverse electromagnetic field oscillates in a plane perpendicular to its propagation direction. Therefore, the two dimensions of field polarization plane are available for manipulation and tailoring of these ultrashort pulses. We present a field that allows such a tailoring, the so-called bicircular field. This field is the superposition of two circularly polarized fields with different frequencies that rotate in the same plane in opposite directions. We present results for two processes in a bicircular field: High-order harmonic generation and above-threshold ionization. For a wide range of laser field intensities, we compare high-order harmonic spectra generated by bicircular fields with the spectra generated by a linearly polarized laser field. We also investigate a possibility of introducing spin into attoscience with spin-polarized electrons produced in high-order above-threshold ionization by a bicircular field.

X-ray Fluorescence Holography: Principles, Apparatus, and Applications

X-ray fluorescence holography (XFH) is an atomic structure determination technique that combines the capabilities of X-ray diffraction and X-ray fluorescence spectroscopy. It provides a unique means of gaining fully three-dimensional information about the local atomic structure and lattice site positions of selected elements inside compound samples. In this work, we discuss experimental and theoretical aspects that are essential for the efficient recording and analysis of X-ray fluorescence holograms and review the most recent advances in XFH. We describe experiments performed with brilliant synchrotron radiation as well as with tabletop setups that employ conventional X-ray tubes.

Distributed state machine supervision for long-baseline gravitational-wave detectors.

The Laser Interferometer Gravitational-wave Observatory (LIGO) consists of two identical yet independent, widely separated, long-baseline gravitational-wave detectors. Each Advanced LIGO detector consists of complex optical-mechanical systems isolated from the ground by multiple layers of active seismic isolation, all controlled by hundreds of fast, digital, feedback control systems. This article describes a novel state machine-based automation platform developed to handle the automation and supervisory control challenges of these detectors. The platform, called Guardian, consists of distributed, independent, state machine automaton nodes organized hierarchically for full detector control. User code is written in standard Python and the platform is designed to facilitate the fast-paced development process associated with commissioning the complicated Advanced LIGO instruments. While developed specifically for the Advanced LIGO detectors, Guardian is a generic state machine automation platform that is useful for experimental control at all levels, from simple table-top setups to large-scale multi-million dollar facilities.

Scanning Small- and Wide-Angle X-ray Scattering Microscopy Selectively Probes HA Content in Gelatin/Hydroxyapatite Scaffolds for Osteochondral Defect Repair.

This study is aimed at investigating the structure of a scaffold made of bovine gelatin and hydroxyapatite for bone tissue engineering purposes. In particular, the detailed characterization of such a material has a great relevance because of its application in the healing process of the osteochondral defect that consists of a damage of cartilage and injury of the adjacent subchondral bone, significantly compromising millions of patient's quality of life. Two different techniques exploiting X-ray radiation, with table-top setups, are used: microtomography (micro-CT) and microdiffraction. Micro-CT characterizes the microstructure in the three dimensions at the micrometer scale spatial resolution, whereas microdiffraction provides combined structural/morphological information at the atomic and nanoscale, in two dimensional microscopy images with a hundred micrometer spatial resolution. The combination of these two techniques allowed an appropriate structural characterization for the purpose of validating the engineering approach used for the realization of the hydroxyapatite gradient across the scaffold, with properties close to the natural model.

テーブルトップ型フェムト秒電子線回折法を用いた超高速構造ダイナミクスの観測

This review written in Japanese is directed to graduate students willing to be part of the emerging field of ultrafast structural dynamics. It provides them with all the basic assumptions and experimental tricks of femtosecond optical spectroscopy and diffraction techniques. The progress in the development of femtosecond X-ray and electron probes during the last twenty years has been tremendous, which provides us with the temporal and spatial resolutions required to observe atoms in motion. Recently, these direct observation of atomic motion with femtosecond X-ray and electron diffraction techniques has gain much attention in the fields of material physics, chemistry or even biology. One good example involves the developments of X-ray free electron laser (XFEL). The table-top femtosecond electron diffraction setups, on the other hand, have comparable brightness and temporal resoution as the facility-top XFELs with proper calibation. This review is mainly focused on generation of ultrashort electron pulses, characterization of the pulses and application for the femtosecond electron diffraction measurements. We now have in hand the ultrafast structural ‘cameras’ ready to be applied for the study of an endless list of dynamical phenomena at the atomic level of inspection.

Grating-based interferometry and hybrid photon counting detectors: Towards a new era in X-ray medical imaging

Progress in X-ray medical imaging and advances in detector developments have always been closely related. Similarly, a strong connection exists between innovations in synchrotron imaging and their implementation on table-top X-ray tube setups. The transfer of phase-based imaging to X-ray tubes can provide table-top setups with improved contrast between areas of low attenuation differences, by exploiting the unit decrement of the real part of the refractive index. Medical imaging is a potential application for such a system. Originally developed for synchrotron experiments, the novel generation of hybrid photon counting detectors is becoming increasingly popular due to their unique characteristics, such as small pixel size, negligible dark noise, fast counting and adjustable energy thresholds. Furthermore, novel room temperature semiconductor materials such as Cd(Zn)Te can provide higher quantum efficiency. In the first part of this article we review phase-contrast techniques and recent research towards medical applications. In the second part we present results and evaluate the potential of combining a table-top Talbot grating interferometry system with latest generation hybrid photon counting detectors.

High photon flux table-top coherent extreme-ultraviolet source

High harmonic generation (HHG) enables extreme ultraviolet radiation with table-top setups. Its exceptional properties, such as coherence and (sub)-femtosecond pulse durations, have led to a diversity of applications. Some of these require a high photon flux and megahertz repetition rates, e.g. to avoid space charge effects in photoelectron spectroscopy. To date this has only been achieved with enhancement cavities. Here, we establish a novel route towards powerful HHG sources. By achieving phase-matched HHG of a megahertz fibre laser we generate a broad plateau (25 eV - 40 eV) of strong harmonics, each containing more than $10^{12}$ photons/s, which constitutes an increase by more than one order of magnitude in that wavelength range. The strongest harmonic (H25, 30 eV) has an average power of 143 $\mu$W ($3\cdot10^{13}$ photons/s). This concept will greatly advance and facilitate applications in photoelectron or coincidence spectroscopy, coherent diffractive imaging or (multidimensional) surface science.

Ultrafast structural dynamics with table top femtosecond hard X-ray and electron diffraction setups

The following tutorial review is directed to graduate students willing to be part of the emerging field of ultrafast structural dynamics. It provides them with an introduction to the field and all the very basic assumptions and experimental tricks involved in femtosecond (fs) diffraction techniques. The concept of stroboscopic photography and its implication in ultrafast science are introduced. Special attention is paid to the generation of ultrashort electron and hard X-ray pulses in table top setups, and a direct comparison in terms of brightness and temporal resolution between current table top and facility-based methodologies is given for proper calibration. This review is focused on ultrafast X-ray and electron diffraction techniques. The progress in the development of fs-structural probes during the last twenty years has been tremendous. Current ultrafast structural probes provide us with the temporal and spatial resolutions required to observe atoms in motion. Different compression approaches have made it possible the generation of ultrashort and ultrabright electron pulses with an effective brightness close to that of fs-hard X-ray pulses produced by free electron lasers. We now have in hand a variety of ultrafast structural cameras ready to be applied for the study of an endless list of dynamical phenomena at the atomic level of inspection.

A perspective on novel sources of ultrashort electron and X-ray pulses

Recently, much attention has been devoted to the development of new pulsed sources of radiation for investigating matter with atomic scale temporal and spatial resolution. While much has been achieved thanks to modern ultrafast laser technology, the ultimate coherent light source, the X-ray free electron laser (X-FEL), promises to deliver the highest X-ray photon flux in the shortest pulses at energies unreachable by conventional solid-state lasers. In parallel, other approaches that utilize electrons in table-top setups as a probe have been developed demonstrating the potential for a valid complement to X-ray based techniques. Here, we consider yet another possible avenue in which the technology of electron diffraction and imaging is pushed further; we estimate the interest and performances of a femtosecond high energy electron microscope and propose a hybrid experiment with relativistic electrons as a probe and fs X-ray pulses as a pump taking advantage of both technologies.

Synchrotron UV−Visible Multispectral Luminescence Microimaging of Historical Samples

UV-visible luminescence techniques are fre-quently used for the study of cultural heritage materials, despite their limitations for identification and discrimination in the case of complex heterogeneous materials. In contrast to tabletop setups, two methods based on the vacuum ultraviolet (VUV)-UV-visible emission generated at a bending magnet of a synchrotron source are described. The main advantages of the source are the extended wavelength range attained, the continuous tunability of the source, and its brightness, leading to a submicrometer lateral resolution. Raster-scanning microspectroscopy and full-field microimaging were implemented and tested at the DISCO beamline (synchrotron SOLEIL, France). Investigative measurements were performed on a sample from a varnished musical instrument and a paint sample containing the pigment zinc white (ZnO) in order to illustrate some of the challenges analyzing heterogeneous cultural heritage cross-section samples with the novel imaging approach. The data sets obtained proved useful for mapping organic materials at the submicrometer scale and visualizing heterogeneities of the semiconductor pigment material. We propose and discuss the combined use of raster-scanning microspectroscopy and full-field microimaging in an integrated analytical methodology. Synchrotron UV luminescence appears as a novel tool for identification of craftsmen's and artists' materials and techniques and to assess the condition of artifacts, from the precise identification and localization of luminescent materials.

Microfabricated saturated absorption laser spectrometer

We demonstrate a miniature microfabricated saturated absorption laser spectrometer. The system consists of miniature optics, a microfabricated Rb vapor cell, heaters, and a photodetector, all contained within a volume of 0.1 cm(3). Saturated absorption spectra were measured with a diode laser at 795 nm. They are comparable to signals obtained with standard table-top setups, although the rubidium vapor cell has an interior volume of only 1 mm(3). We discuss the performance and prospects for using such systems as a miniature optical wavelength reference, compatible with transportable instruments.

A simple pulse-timing system for table-top maser experiments

Pulsers on the basis of silicone controlled rectifiers (SCRs) are intended for pulse supply of different electrical loads in table-top maser experiment setups. The present pulse-timing system, ensuring the needed timing diagrams of the load pulses, forms the required values of time delay of unlocking the SCR by a capacitor, connected between the SCR gate and cathode. Analytical relationships, necessary for preliminary design of the system, have been obtained. Results of the experimental checks correspond to the analysis.