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2nd Terrestrial Very-Long-Baseline Atom Interferometry Workshop

→ Europe/London
Imperial College - London

Imperial College - London
Description

The primary objective of the event is to establish the foundation for an international Terrestrial Very-Long-Baseline Atom Interferometry (TVLBAI) proto-collaboration. This collaborative effort aims to bring together researchers from diverse institutions, fostering strategic discussions and securing funding for terrestrial large-scale Atom Interferometer projects. The goal of the TVLBAI initiative is to develop a comprehensive roadmap outlining design choices, technological considerations, and science drivers for one or more kilometer-scale detectors, which are expected to become operational in the mid-2030s.

 

 

 

Long_Baseline_Workshop_Poster.pdf
OFTP and UK-US Activities.pdf
OFTP and UK-US Activities.pptx
PREF-HOTELS-LONDON-13-12-23 (2).xlsx
TVLBAI Study MOU (24.6.24).pdf
TVLBAI Study MOU - Final .docx
TVLBAI Study MOU - Final .pdf
TVLBAI Study MOU - Final .pdf
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  • Wednesday 3 April
  • Thursday 4 April
    • 08:30
      Coffee Break
    • Session: Atom sources: Scaling atom number and temperature
      Conveners: Dennis Schlippert, Philippe Bouyer, Tiffany Harte
      • 16
        High-flux source of cold strontium atoms
        Speaker: Shayne Bennetts
        20240404 TVLBAI_Bennetts.pdf
      • 17
        Quantum simulation – Engineering & understanding quantum systems atom-by-atom
        Speaker: Monika Aidelsburger
      • 18
        Matter-wave collimation to picokelvin energies with scattering length and potential shape control'
        Speaker: Alexander Herbst
        TVLBAI_04042024_Herbst.pdf
        TVLBAI_04042024_Herbst.pptx
      • 19
        Fast formation of quantum gas for atom interferometers
        Speaker: Shau-Yu Lan
    • Session: Squeezing and multipartite entanglement for atom interferometry
      Conveners: Leonardo Salvi, Richard Hobson
    • 12:30
      Lunch Break
    • Session: Atom interferometry: Metrology & Systematics
      Conveners: Alexandre Gauguet (Université Toulouse 3 - LCAR), Dr Jeremiah Mitchell, Naceur Gaaloul
    • Session: Site & Engineering Challenges for a large-scale AI
      Conveners: Adam Lowe (Oxford University), Robert Plunkett
    • Poster Session & Wine & Coffee
      Conveners: Elizabeth Pasatembou, Leonie Hawkins, Thomas Walker
      • 32
        Alice Josset

        The Atom Interferometer Observatory and Network (AION) detector is subject to a standard limit on its phase resolution due to quantum projection noise when the atomic superposition is collapsed. This limit needs to be overcome for the instrument to be sensitive to gravitational waves and ultra-light dark matter with reasonable atomic cloud sizes, requiring the creation of quantum correlations in the atom cloud. Squeezed states of the atomic ensemble can be generated by performing a quantum nondemolition measurement of the atom number. At Imperial College, we are working towards an atom-cavity system where an atomic transition is strongly coupled to a high-finesse (F=200\ 000) cavity mode. Homogeneous coupling will be achieved by trapping the atoms in an optical lattice formed by a cavity mode oscillating at twice the wavelength of the probe. An entangled state will be created by taking a non-destructive measurement of the atom number with a sweep of the probe field over the vacuum Rabi splitting of the system. In this poster, we present experimental progress towards the creation of the atom-cavity system. This includes the design and characterization of the high-finesse optical cavity and the demonstration of an optical dipole trap in the cavity.

      • 33
        Ashkan Alibabaei

        We investigate the fundamental limits of Large Momentum Transfer (LMT) Atom Interferometry by using the Bloch oscillations of atoms in optical lattices. A thorough theoretical framework for Bloch oscillation-enhanced atom interferometry is presented and validated through a comparison with numerical solutions of the Schrödinger equation. This establishes design criteria to reach the fundamental efficiency and accuracy limits of large momentum transfer using Bloch oscillations. We apply our findings to current state-of-the-art experiments and make projections for the next generation of quantum sensors. Finally, we outline future steps to include the effects of the lattice potential in transverse direction towards a more realistic description. This will facilitate our ability to perform comprehensive analyses of the statistical and systematic errors for future Bloch-en

      • 34
        Chung Chuan Hsu

        Dark matter and gravitational waves help us form a complete description of our understanding of the universe. However, specific subclasses remain elusive for current detectors. The Atom Interferometry Observatory and Network (AION), a consortium of UK institutes, aims to use atom interferometry in strontium to detect them. The sensitivity window of AION probes the millihertz regime where detection gaps currently exist, revealing crucial information about mid-frequency gravitational waves and ultra-light dark matter. To achieve high-fidelity atom-optics interactions, AION would therefore require ultracold atomic temperatures operating on rapid repetition rates with efficient transport to the interferometer. At the University of Cambridge, we are developing technologies to cool and transport atoms efficiently. We are building a small-scale 1m technology demonstrator, which then jointly scales from 10m to 1km for enhanced sensitivities. Here, we report on our production of cold strontium atoms in a 3D “blue” magneto-optical trap (MOT), inside an ultra-high vacuum system that is centrally designed and constructed within AION. We also highlight our advances towards a 3D “red” MOT using a Pound-Drever-Hall locked narrow-linewidth laser and demonstrate initial sightings of atom-number enhancement via atomic shelving. This sets the stage for our next step to produce ultracold atomic clouds rapidly.

      • 35
        Daniel Derr, Enno Giese

        Since the internal structure of atoms is possibly sensitive to dark matter (DM), atomic clocks may serve as suitable DM detectors and provide a platform for detecting violations of the Einstein equivalence principle (EEP). These features are not exclusive to atomic clocks, as atom interferometers can detect EEP violations as well, for example via gravimetry. The atomic diffraction processes envisioned for gravitational-wave detectors also drive internal transitions, which connects clocks and atom interferometers in a natural fashion. Furthermore, the atoms’ centre-of-mass motion is potentially affected by DM as well, making atom interferometers susceptible to DM even without internal transitions. In this contribution we present a unified treatment of internal and centre-of-mass dynamics for atom interferometers, in which relativistic effects, mass defects, and violation parameters (due to DM and EEP) are included. Based on this formalism, we investigate the leading-order effects for atom interferometers with and without internal transitions. Overall, we identify the effects of DM in atom interferometers and discuss the difference between the ones induced by the atom’s clock properties and centre-of-mass effects. See AVS Quantum Sci. 5, 044404 (2023).

      • 36
        Elizabeth Pasatembou

        This study harnesses the exceptional precision of atomic clocks, with uncertainties at least as small as a part in 10^18, to test the boundaries of fundamental physics. By comparing the transition frequencies of different species of atomic clocks can provide constraints on temporal variations in Standard Model fundamental constants, e.g. the proton-to-electron mass ratio (μ) and the fine structure constant (α). We demonstrate an approach to investigate new physics theories beyond the Standard Model, such as those addressing dark matter, dark energy and modified gravity by measuring the variations in μ and α. We focus on sinusoidal oscillations of μ over a one-year period, induced by the Earth’s elliptical orbit around the Sun. In this work, I will outline a preliminary study and its results, aiming to search for variations in μ and α by utilizing publicly available clock data, simulated data for the current and future state-of-the-art atomic clocks and forecasts for future experiments. Our findings advocate for a dedicated experiment that uses atomic clocks to take continuous measurements over the course of a few years. This study highlights the need for advancing quantum sensors, including atomic clocks and atom interferometers, as a tool for probing new physics, which aligns with the workshop’s theme. It also sets the stage for future large-scale experiments designed specifically for making groundbreaking scientific discoveries.

      • 37
        Florentina Pislan

        Ever since the first detection of gravitational waves in 2015 by LIGO and VIRGO collaborations, it became a certitude that they represent important messengers of the most violent and energetic astrophysical processes and of the primordial Universe.
        Current and future gravitational wave detectors are designed to cover a broad spectrum of frequencies, from high (10 Hz to 103 Hz) to very low (< 10-9 Hz), each sensitive to different sources of gravitational waves. In order to be properly prepared to process and understand the amount of information emerging from these missions, the scientists need to compile comprehensive catalogues of potential gravitational wave sources and generate corresponding gravitational wave templates. Here, we present our efforts in creating a catalogue of potential sources that are detectable by low to mid-frequency gravitational wave detectors such as the proposed AEDGE and AION. Also, we do a multi-messenger exploration of the AEDGE/AION potentially detectable gravitational wave sources parameter space, by combining electromagnetic observations with gravitational wave simulations and constraining specific parameters. We also generate a set of simulated gravitational waveforms, intended for the development of future data analysis tools. These tools will be essential in processing and interpreting the data produced by these experiments.

      • 38
        Gedminas Elertas

        MAGIS and AION are long baseline strontium atom interferometry experiments. Both projects will search for the ultralight dark matter fields and lead the technology for a future kilometre-scale detector that would be sensitive to gravitational waves from known sources. To achieve this, MAGIS 100 and AION should demonstrate the shot-noise limited detection, the ability to launch atoms for tens of meters, maintain the record-breaking spatial separation of the wave packets, and account for multiple systematic uncertainties. The University of Liverpool is developing a phase-shear detection platform for both projects. The phase-shear detection is a technique which imprints the interference fringes across the atom cloud, allowing single-shot measurements of the phase and contrast, increasing the repetition rate of the experiment and better control of the systematics, such as Coriolis force. The phase-shear platform consists of an XHV chamber that houses an ultra-high precision 4-inch mirror reflecting the main interferometry beam. The phase-shear fringes are in-printed by precisely controlling the angle of this mirror via in-vacuum piezoelectric actuators. Electronic and optical feedback loops achieve the precise movement of the mirror. The design, specifications, integration into the experiment's detection system, and status are presented.

      • 39
        Hannah Banks

        We propose the nuclear interferometer - a single photon interferometry experiment based upon the nuclear clock transition in neutral thorium atoms - as a novel detector for ultra-light dark matter (ULDM). Thanks to the enhanced sensitivity of this transition to the variation of fundamental constants, we find that modest scale experiments have the potential to match or even improve the discovery potential of advanced very long-baseline terrestrial clock atom interferometers to ultra-light dark matter with scalar couplings to photons. A nuclear interferometer would also offer an unparalleled window to new physics possessing scalar couplings to quarks or gluons, with a reach exceeding other existing and proposed experiments by orders of magnitude over a range of frequencies. We find such a search to be complementary to nuclear-atomic optical clock frequency comparisons, moving in the direction of well-motivated parameter space.

      • 40
        Jiajun Chen, Yijun Tang

        The AION detector requires the delivery of ultracold strontium with a fast repetition rate and large atom number, at the lowest possible temperatures. We will report on our recent progress in developing simulations and experimental techniques for efficient cooling and transport of strontium atoms. Our transport scheme is based on focus-tuneable lenses to dynamically control the focus size and position of a single-beam optical dipole trap, moving pre-cooled strontium clouds into the interferometry chamber. One feature of this scheme is that the focus size can be maintained over the transport process, providing a uniform trapping condition but with independent tuning of the trap size when required. We aim to minimise heating and atom loss during this process by utilising custom low-noise drive electronics with feedback for stabilisation, and choosing a careful acceleration and intensity profile for the transport beam. To provide insight into experimental parameters, we carry out simulations in AtomECS, an open-source cold atom simulation platform. We simulate the loading of a crossed-beam dipole trap from a red MOT, then loading of the single-beam dipole trap for optical transport. We use these to investigate optimal parameters for each loading stage and the acceleration profile of the optical transport ramp.

      • 41
        John Carlton

        Atom interferometers are powerful new tools for probing many aspects of fundamental physics including searches for gravitational waves and dark matter. The construction of several long-baseline terrestrial atom interferometer experiments is underway and thus fully characterising the noise these experiments are subject to is of paramount importance. Gravity gradient noise (GGN) from seismic waves has long been known as a leading source of noise for long-baseline laser interferometer experiments such as LIGO. In general, this noise scales inversely with frequency also making it a challenge for atom interferometer experiments which operate at lower frequencies. Recent studies of GGN for atom interferometers have primarily focussed on seismic effects; however, atmospheric density perturbations from temperature and pressure fluctuations will also be a significant source of noise. In this work we characterise the spectrum of atmospheric pressure and temperature GGN, building on previous investigations for laser interferometry and generalising the results to low frequency, vertical atom interferometer experiments. We evaluate how this noise depends on an experiment’s location on the Earth’s surface and estimate a high and low noise model for atmospheric GGN to complement the existing Peterson models for seismic effects.

      • 42
        Jonathan Ramwell (Toptica)

        Small table-top display for Toptica

      • 43
        Jordan Gué

        We present a theoretical investigation of the expected experimental signals produced by freely falling atoms with time oscillating mass and transition frequency. These oscillations could be produced in a variety of models, in particular, models of scalar dark matter (DM) non universally coupled to the standard matter (SM) such as axion-like particles (ALP) and dilatons. Performing complete and rigorous calculations, we show that, on one hand, two different atomic species would accelerate at a different rate, and on the other hand, they would produce a non-zero differential phase shift in atom interferometers (AI). The former would produce observable signals in equivalence principle tests like the recent MICROSCOPE mission, and we provide a corresponding sensitivity estimate, showing that MICROSCOPE can reach beyond the best existing searches in the ALP case. We also compare the expected sensitivity of two future AI experiments, namely the AION-10 gradiometer and an isotope differential AI considered for MAGIS-100, that we will refer to as SPID. We show that the SPID setup would be more sensitive to these dark matter fields compared to the gradiometer one, assuming equivalent experimental parameters.

      • 44
        Junjie Jiang

        As a fundamental assumption of general relativity, the test of the equivalence principle plays a key role in exploring the applicability of the physical framework and seeking new physics. In 2015, we developed the four-wave double-diffraction Raman transition (4WDR) method and tested the equivalence principle for 85Rb-87Rb [1], and in 2021 further expanded to the joint mass and energy test of the equivalence principle [2]. Recently, using the phase shear readout method, we achieved an atom interferometry with free evolution time of 2T=2.6 s for 87Rb atoms, which is the longest in a laboratory setting so far, and the gravity measurement resolution of a single shot is 4.5×10-11 g [3]. On this basis, we have improved cold atomic fountain and Raman lasers to achieve a dual-species atom interferometry with T=650 ms, enhancing the differential measurement resolution to 8.6×10-12. Other unit technology improvement includes the realization of the preparation of dual-species ultra-cold atomic ensembles, and proposed a method that simultaneously coincides the centroid position and velocity of the dual-species atomic ensembles using atomic lensing technology [4]. About phase shear readout, we proposed a method to extract absolute phase and suppress position drift noise [5], these advances have laid the found ation for higher precision test of the equivalence principle.

      • 45
        Kamran Hussain

        AION (Atom Interferometer Observatory and Network) and MAGIS (Matter-wave Atomic Gradiometer Interferometric Sensor) are a consortium of strontium atom interferometry experiments, with the science goals of probing gravitational waves in the mid-band detection region between 0.1-10 Hz and to search for ultra-light dark matter candidates. MAGIS is currently constructing the 100 m vertical baseline in the MINOS access shaft at Fermilab. AION plans to build the 10 m detector at the University of Oxford, with prospects of setting up the 100 m baseline in Boulby Underground Laboratory. Rutherford Appleton Laboratory hosts one of five strontium labs in the AION consortium with a 1m interferometer. This is a testbed to understand and further develop cold atom technologies that required for the 10 m AION tower. Currently a 2D Magneto-Optical Trap (MOT) has been formed, with progress towards setting up the next cooling stage for the 3D MOT. The goal is to achieve strontium interferometry with the potential to test the out-of-vacuum phase-shear imaging platform in collaboration with the University of Liverpool.

      • 46
        Leonardo Badurina

        In this study, we extend the physics case of future terrestrial very-long baseline and space-based atom gradiometers by considering the reach of such experiments to ultra-heavy dark matter with masses exceeding the Planck scale. We study the phase-shift signatures in a coordinate-invariant fashion and find three distinct contributions that would be measurable in experiments such as AION, MAGIS and AEDGE: the gravitational redshift, the Doppler effect (i.e. the acceleration of the atoms) and the Shapiro effect (i.e. the gravitational time delay accumulated during photon propagation). Although our work finds that only AEDGE may be able to probe unexplored regions of dark matter parameter space, we highlight that our framework can be used to analyze the phase shifts induced by slow-varying and weak Newtonian potentials independently of their nature, which will prove especially helpful in systematically studying the phase shift noise from transient objects.

      • 47
        Leonie Hawkins

        A previously decommissioned frequency standard fountain, repurposed for atom interferometry at the National Physical Laboratory with the University of Liverpool, has been relocated to Liverpool and is currently in operation with an upgraded laser system. The device will serve as a prototype detector to test for fundamental physics concepts beyond the standard model and can act as a test stand for quantum technology and inertial sensing applications. The set-up is capable of trapping and cooling ~109 rubidium-85 atoms in a 3D MOT from a low-velocity intense source, followed by launching using a moving molasses configuration, and an interferometry sequence in a ~1 m magnetically shielded region. A significant upgrade to laser power and frequency control for the cooling, repumper and Raman systems is underway. The interferometer is in a fountain configuration, so the upgrade also includes the ability to launch atoms, improved state selection, incorporation of an active vibration control system and a new detection system. Progress on the fountain, upgrading the laser system, and the planned new vacuum chamber will be reported.

      • 48
        Ludovico Iannizzotto Venezze

        Atomic clocks have a remarkable precision below 10-18, making them well suited for studies of fundamental physics. For example, we can use clocks to search for ultra-light scalar dark matter by probing variations in the fine structure constant. Constraints on dark matter's coupling strength with normal matter have already been published with the use of different clocks and the field is now pushing for ever-better stabilities to improve these constraints. Despite recent advancements, state-of-the-art optical clocks still suffer the limits imposed by their sequential operation and the Dick noise that comes with it. In the Ultra-precise, Shock-resistant Optical Clock (USOC) project, we aim to build a novel Sr ultra-cold atomic system operating continuously, therefore eliminating the dead-time and oscillator noise present in conventional optical clocks. This system will be able to reach unprecedented levels of stability and will require the development of new techniques to produce a continuous high-flux source of ultra-cold atoms and a conveyor-belt lattice trap to transport them. In this poster I would like to outline the advantages of continuously-operating optical clocks, their use in the search for ultra-light dark matter and how we aim to achieve this in the USOC project.

      • 49
        Maria Isfan

        "The detection of gravitational waves is an area of active research, with important upcoming missions that will listen to gravity from space. The future datasets coming from these missions are expected to be large and complex, creating the need for the development of improved data analysis tools, able to extract meaningful information from gravitational wave data. Here, we present our approach towards obtaining a highly performant gravitational wave data analysis tool by combining the robust capabilities of neural network techniques with the cutting-edge potential of quantum computing. In the context of our involvement in the development of the future space missions LISA and AEDGE, we have been developing a quantum neural network based low latency pipeline for the rapid and accurate detection of gravitational wave signatures within simulated detector signals. We successfully trained and tested it to recognize realistic data, embedded within complex noise and modelled to mimic detection by LISA instruments. Our future plans include implementing our pipeline on real quantum hardware with the purpose of performing a benchmarking of two prominent technologies, superconductivity and cold atoms. Our study will not only address the gravitational wave analysis but also assess the feasibility of quantum technologies in large-scale data processing."

      • 50
        Michael Werner

        Atom interferometers (IFs) are highly accurate sensors of gravitational fields and their gradients, and are increasingly important for applications in industry and geodesy. Asenbaum et al. [2017] have investigated the 'tidal phase' that arises in a Mach-Zehnder interferometer (MZI) from the interplay of the gravitational gradient and atomic recoil. The tidal phase was extracted in a differential measurement with and without a test mass lead block causing the gravitational gradient. Since then, the tidal phase has attracted growing attention for its potential to measure spacetime curvature and to observe the `gravitational Aharonov-Bohm effect', cf. Overstreet et al. We present a novel interferometer scheme that provides the tidal phase -- due to the Earth or any additional test mass -- as the dominant phase contribution, without the need to perform differential measurements with and without a test mass. Competing finite speed of light (FSL) phase shifts can be mitigated by appropriate adjustment of the final IF pulse.

      • 51
        Oliver Ennis

        As part of the AION consortium, the University of Birmingham is investigating the enhancement of large momentum transfer (LMT). The sensitivity goals for AION aim for LMT which is an improvement of a factor of over 500 times the current state of the art for strontium. Modelling suggests that hybrid solutions are required which utilise various advanced techniques simultaneously, including composite pulses, pulse shaping and wavefront control. Enhancement of LMT will benefit both laboratory-based fundamental physics experiments and the commercial devices based on atom interferometry. In my poster I will provide an overview of the work towards AION at Birmingham, with a focus on both the laboratory progress and the theoretical exploration of LMT.

      • 52
        Sebastian Wald

        Entangled Mach-Zehnder type Atom Interferometer in an optical, propagating-wave cavity In our experiment, an optical, propagating wave cavity mediates entanglement of the atomic ensemble and it supports the Raman beam splitter operation, while keeping the atoms trapped during the whole interferometer sequence. We present the experimental parameters of the cavity that enable the generation of an atomic spin-squeezed state and the mapping of this entanglement onto the arms of the Mach-Zehnder via a state-dependent momentum kick. Furthermore, we demonstrate the dipole trap generated by the cavity and we discuss how AC-stark shifts will be compensated by a weak blue-detuned auxiliary potential.

      • 53
        Selyan Beldjoudi

        We present a novel approach to achieve Large Momentum Transfer (LMT) through stroboscopic stabilization of a Floquet state in an accelerated optical lattice. Using optimal control protocols, we prepare the Floquet state, enabling fast LMT and significantly improving the efficiency of the beam splitter. Using this technique, we demonstrate an atom interferometer with a maximum momentum separation of 600 photon recoils (600ћk). In addition, we characterize the robustness of these protocols to BEC velocity dispersion and lattice depth fluctuations.

      • 54
        Simon Hack

        We are currently setting up a lattice atom interferometer, which coherently levitates the atomic wave function allowing us to circumvent the limitation given by the gravitational free fall time of the atoms. By holding a spatial superposition of K-39 atoms in a cavity enhanced optical lattice, ultra-long interaction times on the minute scale can be achieved. Furthermore, with this setup we will be capable of conducting precision measurements of short-ranging potentials to search for new physics, light induced inter-particle interactions or precise characterization of atom-surface interactions. The experiment consists of a transfer chamber separated by a valve to a science chamber, which facilitates the insertion of samples, e.g. test masses to measure their effect on the potassium atoms, but also allows for inserting tailored electron beams to perform experiments to investigate coherent interaction between atoms and electrons.

      • 55
        Thomas Walker

        Atom interferometers are limited in resolution by quantum projection noise, and so require high atomic flux. Here we present the designs for a ultracold strontium source for atom interferometry and optical atomic clock experiments. The design is focused on yielding a high atomic flux while minimising size, weight, and power consumption.
        The system will include a vacuum chamber for Zeeman cooling atom from an oven and loading them into a 2D magneto-optical trap, and conveying them into a second chamber via a moving optical molasses. The second chamber will be used to characterise the atom source. The Zeeman slower will have a tailored magnetic field profile formed by a series of permanent magnets in a Halbach configuration, with a multi-tone Zeeman slowing beam ensuring a broad capture velocity range. Permanent magnets for producing the magnetic fields reduce weight and power consumption, and remove the need for water cooling, while small shim coils allow for tailoring of the field profile. The permanent magnets sit in position-adjustable mounts recessed into the vacuum chamber, to allow large, tuneable field gradients in the first chamber while minimising the impact on the second chamber.

      • 56
        Vishu Gupta

        "The Very Long Baseline Atom Interferometry (VLBAI) facility at the Hannover Institute of Technology opens up exciting possibilities for highly precise inertial measurements, with applications spanning from fundamental physics to geodesy. The 10-meter baseline facility, equipped with Bose-Einstein Condensates (BECs) and a high-performance Seismic Attenuation System (SAS), holds tremendous potential for the development of a highly accurate and sensitive absolute gravimeter. VLBAI employs the Bragg interferometer scheme to measure the acceleration due to gravity of freely falling atoms along the baseline. Here, we present our recent advancements towards the atom interferometry by launching Rb BECs along the baseline. To this point we have demonstrated a millimeter launch by accelerating the optical dipole trap and the bragg beam splitter using the all-optical cold Rb atom source at VLBAI. We show the current status of the all-optical Rb-BEC source, a first characterization of the passive vibration isolation performance and the necessary methods such as matter-wave lenses, Bragg beam splitters and initial momentum kick for the inertial measurements with VLBAI."

  • Friday 5 April
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