The Standard Model has been extremely successful in making experimental predictions in the past decades, yet leaves some key phenomena unexplained. In particular, it does not include gravity and does not explain dark matter. We are a consortium of UK universities creating a world-leading multidisciplinary programme to search for dark matter and for quantum aspects of space-time. Both of these research directions use the common technological platform of quantum-enhanced interferometry. We leverage expertise developed within the National Quantum Technology Programme in optical resonators, quantum sources of light, and single photon detectors to address the fundamental physics problems.
Our first research direction is devoted to searches for dark matter and other particles beyond the Standard Model. There are many theories that try to explain the nature of dark matter. Analyses of a range of observations, including the rotation velocities of galaxies, the dynamics of galaxy clusters, microlensing, and the large-scale structure of the universe led most of the scientific community to accept non-baryonic particles as the primary dark matter candidates. Weakly interacting massive particles (WIMPs) were the most promising candidate over the last few decades. However, a set of ultra-sensitive WIMP detectors, such as XENON, LUX, and PandaX, have not observed dark matter to date and will reach the neutrino background in the near future. Therefore, we search for the other very promising non-baryonic dark matter candidates: axions and axion-like-particles.
Our second research direction searches for quantum aspects of space-time. Quantum mechanics and the general theory of relativity have successfully passed all experimental tests to date. For example, quantisation of the motion of a macroscopic object has recently been demonstrated. And propagation of errors in modern quantum computers, such as Google’s Sycamore does not show any signs of unexpected decoherence in a highly entangled state. At the same time, recent observation of gravitational waves from binary black holes and binary neutron star mergers proved that the general theory of relativity also holds in a very strong gravitational field. The main related and long-standing research question is: How can gravity be united with the other fundamental forces? To seek answers that inform this question, we propose to study two quantum aspects of space-time.
Our research programme Quantum-enhanced Interferometry for New Physics is funded by the UKRI Science and Technology Facilities Council and Engineering and Physical Sciences Research Council under the Quantum Technologies for Fundamental Physics initiative.
Axion interferometer
There are many theories that try to explain the nature of dark matter. Analyses of a range of observations, including the rotation velocities of galaxies, the dynamics of galaxy clusters, microlensing, and the large-scale structure of the universe led most of the scientific community to accept non-baryonic particles as the primary dark matter candidates.
The physical principle of axion-like-particle searches pursuits by our group is to explore a phase velocity difference between left- and right-handed circularly polarized light which propagates in the presence of axion-like-particle fields. We build a quantum-enhanced interferometer to measure the phase difference induced by axions with masses from 10-16 eV up to 10-8 eV.
Figures:
Figure 1: Layout of the experiment
Figure 2: Plan of the laboratory (currently under construction)
Figure 3: Expected sensitivity
Selected publications:
Quantum-enhanced interferometry for axion searches
Searching for axion dark matter with birefringent cavities
For more information contact: Haixing Miao, Vincent Boyer, Denis Martynov
Any light particle search
We are building an advanced superconducting transition-edge-sensor (TES) platform to enhance the ALPS sensitivity. This quantum detector will be built in collaboration with DESY and NIST. The project will position the UK as a key partner in the ALPS collaboration, which has ambitious goals to build the next generation of detectors in a km-scale facility.
The ALPS experiment is currently in its second generation under a collaboration of DESY, University of Florida, the Max-Planck-Institute (AEI) in Hannover, Mainz University, and Cardiff University. The ALPS setup does not rely on the assumption that axions, axion-like-particles, and other weakly interacting slim particles (WISPs) account for dark matter in the galactic halo. Instead, the instrument creates and detects its own axions via a large-scale "light-shining-through-a-wall" experiment. WISPs are produced in a 5.3 T magnetic field inside a 120-m long optical resonator, travel through a dark screen, convert back to photons in an identical resonator, and are detected on a single photon detector.
Figures:
Figure 1: Layout of the experiment
Figure 2: Picture of the ALPS vacuum tubes. Image credit: DESY/Marta Mayer
Figure 3: transition edge sensor
Selected publications:
Design of the ALPS II Optical System
For more information contact: Robert Hadfield, Dmitry Morozov, Hartmut Grote
Quantisation of space-time
This project is related to the holographic principle, which states that the information content of a volume of space can be encoded on a lower-dimensional boundary of that volume. Certain theoretical models of the holographic principle suggest space-time correlations that can be measured by a pair of co-located optical interferometers.
Some models were tested by the Fermilab Holometer experiment and null results obtained. We propose to build a more sensitive and flexible table-top setup which can be adjusted to study a wider range of models of holographic correlations, including implications from an exciting development arising from new observations of angular correlations in the CMB background.
Figures:
Figure 1: Layout of the experiment
Figure 2: Picture of the laboratory
Figure 3: Expected sensitivity of the experiment
Selected publications:
An Experiment for Observing Quantum Gravity Phenomena using Twin Table-Top 3D Interferometers.
For more information contact: Kate Dooley, Hartmut Grote, Animesh Datta
Cryogenic silicon optomechanics
Cryogenic silicon technology promises significant reduction of thermal noises and is considered by the GW community as the key element of the future GW antennas, such as Cosmic Explorer and Einstein Telescope. In this experiment, we explore macroscopic quantum mechanics phenomena, such as quantum back-action noise, with silicon mirrors.
In our group, we are building an experiment that will show the feasibility of preparing a macroscopic quantum-limited system within a regular laboratory environment. This will be achieved by suspending a cryogenically cooled, high-finesse optical cavity via a multi-stage suspension. We motivate the utility of our experiment in providing an increased understanding of the nature of quantum fluctuations in current and future gravitational wave detectors, as well as opening an avenue for research into aspects of macroscopic quantum mechanics and quantum gravity.
Figures:
Figure 1: Layout of the experiment
Figure 2: Manufactured parts of the suspension system
Figure 3: CAD model of the suspension system
Selected publications:
Towards the Standard Quantum Limit in a Table-Top Interferometer
Quantum correlations of light mediated by gravity
For more information contact: Jiri (George) Smetana, Stuart Reid, Denis Martynov
Optical cavities
Optical cavities are at the core of many modern experiments, including gravitational-wave detectors, optical atomic clocks, and quantum optomechanical experiments. Laser light bouncing thousands of times between the cavity mirrors provides the world-best readout technique of the mirror position within the cavity.
In our group, we develop new optical interferometers to search for dark matter, quantisation of space-time, and semiclassical gravity.
Figure: LIGO vacuum equipment. Credit: LIGO MIT.
Selected publications:
Sensitivity of the Advanced LIGO detectors at the beginning of gravitational wave astronomy
For more information contact: Hartmut Grote, Denis Martynov
Squeezed light
Precision measurement has been a primary driving force for advancing modern science. But how can we further improve optical measurements? The fundamental limit to their precision comes from the quantum nature of light. Poissonian distribution of the photon number in the laser beam cases quantum shot and back-action noises on photodiodes and suspended mirrors.
In our group, we study two approaches towards the suppression of quantum noises. First, we optimise the response of gravitational-wave antennas to signals in a particular frequency band. Second, we explore a new paradigm using quantum amplification that complements the squeezing technique and is robust against optical losses..
Figure: Squeezed light. Credit: A. Franzen and T. Steinhaus.
Selected publications:
Proposal for Gravitational-Wave Detection Beyond the Standard Quantum Limit via EPR Entanglement
For more information contact: Kate Dooley, Hartmut Grote, Vincent Boyer.
Transition edge sensors
The past decade has seen a dramatic increase in interest in new single-photon detector technologies. A major cause of this trend has undoubtedly been the push towards optical quantum information applications. These new applications place extreme demands on detector performance that go beyond the capabilities of established single-photon detectors.
The ALPS II photosensor is a tungsten transition-edge sensor (W-TES) optimized for 1064 nm photons. This TES, operated at 80 mK, has already allowed single infrared photon detections as well as non-dispersive spectroscopy with very low background rates. In our group, we develop a new TES to further reduce number of dark counts in the detectors.
Figure: Transition edge sensors. Credit: NIST.
Selected publications:
Single-photon detectors for optical quantum information applications
For more information contact: Robert Hadfield, Dmitry Morozov
Optical coatings
Extreme-performance optical coatings are essential for both scientific and industrial applications. In particular, gravitational-wave detectors are limited by coating thermal noise in their most sensitive frequency band. We also need better coatings for photonics and laser applications, particularly for increasing the laser damage threshold, and for optical atomic clocks.
Amorphous silicon has ideal properties for many applications in fundamental research and industry. However, the optical absorption is often unacceptably high, particularly for gravitational-wave detection. In our group, we develop a novel ion-beam deposition method for fabricating amorphous silicon with unprecedentedly low unpaired electron-spin density and optical absorption.
Figure: Optical coatings. Credit: EGO/Virgo Collaboration/Perciballi.
Selected publications:
Amorphous Silicon with Extremely Low Absorption: Beating Thermal Noise in Gravitational Astronomy
For more information contact: Stuart Reid, Denis Martynov
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Lorenzo Aiello Cardiff University Research Associate Experimental quantum optics |
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Vincent Boyer University of Birmingham Experimental quantum optics Equality, diversity and inclusion officer |
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Animesh Datta University of Warwick Theoretical quantum optics |
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Artemiy Dmitriev University of Birmingham Research Fellow Dark matter |
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Kate Dooley Cardiff University Experimental quantum optics |
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Aldo Ejlli Cardiff University Research Associate Experimental quantum optics |
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Hartmut Grote Principal Investigator Cardiff University Holographic noise |
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Robert Hadfield University of Glasgow Single photon detectors |
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Joscha Heinze Research Fellow Dark matter Quantum optics |
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Kanioar Karan University of Cardiff Research Fellow Experimental quantum optics |
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Denis Martynov Deputy PI University of Birmingham Dark matter Semiclassical gravity |
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Haixing Miao University of Birmingham Dark matter Semiclassical gravity |
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Devendra Kumar Namburi University of Glasgow Research Fellow Single photon detectors |
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Stuart Reid University of Strathclyde Optical coatings |
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Dmitry Morozov University of Glasgow Research Fellow Single photon detectors |
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Jiri (George) Smetana University of Birmingham Research Fellow Cryogenic silicon |
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Steve Beaumont Project Partner QUANTIC Single photon detectors |
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Kai Bongs Project Partner QH in Sensors and Timing Optical cavities |
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Yanbei Chen Project Partner Caltech Semiclassical gravity |
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Matthew Evans Project Partner MIT Dark matter |
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Craig Hogan Project Partner Fermilab Holographic noise |
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Axel Lindner Project Partner DESY ALPS II experiment |
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Moritz Mehmet Project Partner AEI Hannover Quantum optics |
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Sae Woo Nam Project Partner NIST Single photon detectors |
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Henning Vahlbruch Project Partner AEI Hannover Quantum optics |
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Tianliang Yan University of Birmingham Research fellow Cryogenic silicon |
Our oversight committee and advisory board
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Clare Burrage University of Nottingham |
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James Hough University of Glasgow |
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Alexander Lvovsky University of Oxford |
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Paola Arias Reyes Universidad de Santiago de Chile |
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Kamalam Vanninathan STFC |
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Stafford Withington University of Cambridge |
PhD positions:
Every year our groups offer new PhD positions to drive our experimental effort forward. The list of available 2021 PhD projects is listed below:
Cardiff University: Searching for Quantization of Space-time with quantum-enhanced interferometers.
Laser interferometers have long been used to probe fundamental physics phenomena, from disproving the existence of the theorized ether well over a hundred years ago to making the first direct detections of gravitational waves in recent years. Given the extraordinary measurement precision that can be achieved with the latest technological advances in laser interferometer design, they can now also be used for challenging questions in fundamental physics, such as searching for the potential quantization of spacetime, dark matter, and ultra-high frequency gravitational waves. In our labs in Cardiff we are in the process of building the most sensitive table-top interferometer to date, including non-classical states of light such as squeezed light to improve sensitivity. Should you join our team, a potential project could be the development of our high-frequency data-acquisition system (which samples 8 channels with 500 Million samples per second each) and its data-analysis pipelines. These pipelines search for signs of quantization of spacetime, dark matter, and high-frequency gravitational waves. This unique precision experiment also provides exciting opportunities for working on other systems, such as adaptive optics that can be controlled with machine learning techniques, and adaptive interferometer feedback control and noise analysis techniques.
University of Birmingham: Cryogenic Silicon Optomechanics
Quantum mechanics has triggered the development of the crucial technology for modern optical precision measurements: lasers. However, the Heisenberg uncertainty principle for the amplitude and phase quadrature of the laser field sets fundamental limits on the precision of the interferometric measurements. Quantum back-action noise on the LIGO mirrors from the laser field degrades the detector sensitivity below 30 Hz. Quantum shot noise in the LIGO photodetectors limits its sensitivity above 100 Hz. The aim of this project is to experimentally observe quantum noises and investigate its properties, such as quantum correlations. The quantum noise arises due to the interference of vacuum fields and static laser fields inside optical cavities and drives suspended mirrors with a random force. Members of our group currently set up an experiment with high-finesse suspended optical cavities which are compact prototypes of the km-scale LIGO detectors. PhD student will acquire skills in quantum optics, electronics, laser physics, feedback control, vibration isolation systems, data analysis. The project will include both experimental and theoretical work as well as simulations of quantum interactions.
University of Birmingham: Optical Coatings
Optical cavities are in the core of many precision instruments, such as optical atomic clocks, gravitational-wave detectors, optical rotation sensors, and quantum opto-mechanical setups. In this project, PhD student will investigate the properties of the key components of optical resonators: optical coatings. These thin films reflect light from the mirror surfaces and are formed by alternating layers of materials with different refractive indices. Optical coatings can be manufactured in a variety of configurations. In particular, number, thickness, and even material of alternative layers can be varied to minimise optical losses and coating noises. PhD student will experimentally investigate properties of the state-of-the-art coatings in a multi-mode optical resonator in collaboration with the members of UK National Quantum Hub in Sensors and Timing.
Postdoc positions:
University of Birmingham: research fellow in precision measurements. Apply now!
Optical cavities are in the core of many precision instruments, such as optical atomic clocks, gravitational-wave detectors, optical rotation sensors, and quantum opto-mechanical setups. In order to advance precision measurements, we are building a facility to measure properties of the key components of optical resonators: optical coatings. Our measurement procedure is a crucial step in manufacturing high-quality coatings because we need to experimentally explore the whole parameter space of coating production, such as deposition rate, doping materials, and annealing.
Faculty positions:
University of Birmingham: Assistant/assosiate professor in experimental physics. Apply now!
The School of Physics and Astronomy and Institute for Gravitational Wave Astronomy invite applications for three faculty positions in areas relevant to gravitational-wave and multi-messenger astronomy, including experimental physics, gravitational-wave instrumentation, observational astronomy, theoretical astrophysics and general relativity. The Institute for Gravitational Wave Astronomy has a rich portfolio of research activities in experimental physics, instrumentation, data analysis and observations, theoretical astrophysics and general relativity, and transients and multi-messenger astronomy. Institute members play active roles in the GEO Collaboration and the LIGO Scientific Collaboration – including the development of next generation ground-based gravitational-wave observatories – the LISA Consortium, the European and International Pulsar Timing Array Collaboration, and surveys such as ENGRAVE, ePESSTO+ and LSST. The Institute has excellent laboratory and computer facilities. The Institute is affiliated with the Astrophysics and Space Research group, one of the eight research groups in the School of Physics and Astronomy.
Send your questions about jobs to
Warwick: Animesh Datta
Cardiff: Hartmut Grote
Glasgow: Robert Hadfield
Birmingham: Denis Martynov
Strathclyde: Stuart Reid
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