Emblem of the Birmingham GW Institute

Overview

The LIGO and Virgo gravitational-wave (GW) detectors are the most sensitive distance meters ever buit. During the latest science run, they achieved a precision of 1 part in 1023 for the distance fluctuations between the two mirrors separated by 4 km. This precision has allowed the astrophysics community to observe GW from black holes and neutron stars, test the general theory of relativity in the strongest gravitational regime, estimate population of compact objects in the universe, and even measure the Hubble constant.

The LIGO detectors became successful due the state-of-the-arm technologies developed by the collaborators world-wide. Birmingham has been a part of the Advanced LIGO UK Project from the outset. We developed and built sensors, actuators and control electronics for the instrument’s suspensions, a decisive sub-system that enabled the detections. The next generation of these devices for the A+ upgrade are under development in our group now. In parallel, we have carried out a much broader range of commissioning activities throughout LIGO O1-O3 observing runs.

Our experimental group is a part of the Birmingham Institute for Gravitational Wave Astronomy and Astrophysics and Space Research Group, where we apply our expertise in instrumentation and LIGO commissioning to the wide-ranging experimental R&D programme. Join our group to develop new technologies for future GW detectors, study quantum optomechanics, and search for axion dark matter. We are members of the Quantum Interferometry (QI) collaboration where apply precision measurement techniques to fundamental physics problems.

Research

LIGO chambers

Future detectors

The discoveries made by the LIGO and Virgo gravitational-wave detectors have had a transformative impact and triggered a new era in astronomy. Taking full advantage of the GW window requires a new network of observatories that can survey the Universe on its largest scales and provide information of broad interest in astrophysics, cosmology, and nuclear physics.

In our group, we work on the design of the future gravitational-wave detectors which can be hosted in the current or future facilities. In particular, we proposed an optical layout for observing signals from neutron star oscillations above 1 kHz. We also studied the low-frequency performance of the LIGO detectors and proposed a strategy to observe signals from intermediate-mass black holes below 30 Hz.

Figure: LIGO vacuum equipment. Credit: LIGO MIT.

Selected publications:

Exploring the sensitivity of gravitational wave detectors to neutron star physics

Prospects for Detecting Gravitational Waves at 5 Hz with Ground-Based Detectors

Towards the design of gravitational-wave detectors for probing neutron-star physics

Related experimental projects: Cryogenic silicon, 6D Seismometer

For more information contact: Haixing Miao, Denis Martynov

LIGO optics

Quantum optics

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: LIGO vacuum equipment. Credit: EGO/Virgo Collaboration/Perciballi.

Selected publications:

Proposal for Gravitational-Wave Detection Beyond the Standard Quantum Limit via EPR Entanglement

Quantum correlation measurements in interferometric gravitational-wave detectors

Related experimental projects: Cryogenic silicon, Quantum amplifiers

For more information contact: Haixing Miao, Denis Martynov, Teng Zhang.

L4C with optical readout

Seismic isolation

Sensors and actuators are the key pieces of hardware responsible for keeping the LIGO detectors in the linear regime. State-of-the-art seismic isolation system in the LIGO detectors is particularly important for studying intermediate-mass black holes, for localisation, and for accumulating signal-to- noise ratio from lighter sources.

In our group, we pursuits three research directions to improve seismic isolation of the future LIGO detectors: (i) a 6D seismometer for isolating the LIGO optical tables from the environment, (ii) cryogenic position sensors for future gravitational-wave detectors, (iii) interferometric position sensors to improve the sensitivity of the LIGO detectors at low frequencies.

Figure: L4C geophones with optical readout. Credit: Sam Cooper.

Selected publications:

A 6D interferometric inertial isolation system

A compact, large-range interferometer for precision measurement and inertial sensing

Sensors and actuators for the Advanced LIGO mirror suspensions

Related experimental projects: Position sensors, 6D Seismometer

For more information contact: Haixing Miao, Denis Martynov

Axion field

Dark matter

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. It is essential to increase the number of searches for the other very promising non-baryonic dark matter candidates: axions and axion-like-particles.

In our group, we build a novel quantum-enhanced interferometer to measure this axion-like-particle-induced phase difference between the two polarisation eigen modes of the optical cavity. If successful, our layout can be utilised in the LIGO facilities for the axion searches when new longer gravitational-wave facilities become available in the 2030s.

Figure: Artist's representation of axions. Credit: Quanta magazine.

Selected publications:

Quantum-enhanced interferometry for axion searches

Related experimental projects: Axion interferometer

For more information contact: Haixing Miao, Denis Martynov

Projects

SQL cryostat
SQL sus model
SQL layout

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: Manufactured parts of the suspension system

Figure 2: CAD model of the suspension system

Figure 3: Layout of the experiment

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, Denis Martynov

6D design
6D tank
6D ISI motion

6D seismometer

Pushing this seismic wall in GW detectors to lower frequencies will have two critical effects: expansion of the astrophysical reach and reduction of the impact of environmental disturbances on the observatories. We propose to solve the problem of ground vibrations with a 6D seismometer which measures the bench motion in all 6 degrees of freedom with optical sensors.

In our group, we perform the full set of tasks related to the development of the 6D seismometer: simulations, CAD modelling, and experimental research.

Figures:

Figure 1: CAD model of the experiment

Figure 2: Picture of the vacuum tank and crane

Figure 3: Predicted improvement of the isolation

Selected publications:

A 6D interferometric inertial isolation system

For more information contact: Leonid Prokhorov, Sam Cooper, Amit Ubhi, Chiara Di Fronzo, Denis Martynov

CTN modes
CTN layout
CTN reference cavities

Optical coatings

Optical coatings are formed by alternating layers of materials with different refractive indices and are utilised to reflect light from the mirror surfaces. Thermal motion of atoms inside optical coatings leads to the random phase modulation of light and noise in the readout channel of the gravitational-wave detectors, optical atomic clocks, and quantum optomechanical systems.

In collaboration with the UK National Quantum Hub in Sensors and Timing, we build an MIT-type experiment to measure properties of the key interferometric components: optical coatings, at 1550 nm. The key idea of the measurement is to resonate two beams in the same optical cavity and make all noises common to these beams, except for the thermal noises.

Figures:

Figure 1: Simulated beam profile on the sample mirror

Figure 2: Optical layout of the experiment

Figure 3: Stability of reference cavities with current and future coatings

Selected publications:

Audio-band coating thermal noise measurement for Advanced LIGO with a multimode optical resonator.

For more information contact: Teng Zhang, Denis Martynov

Axion layout
Axion sensitivity
Axion detection scheme

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: Experimental layout

Figure 2: Scheme of the laboratory (currently under construction)

Figure 3: Expected sensitivity

Selected publications:

Quantum-enhanced interferometry for axion searches

For more information contact: Haixing Miao, Denis Martynov

Sensors tank
Sensors BOSEM
Sensors HoQI

Position sensors

Operation of GW detectors at low temperature offers potentially great benefits, as well as major challenges. The GW community is exploring the Voyager concept, which has silicon test masses operating at 123 K. We work on expanding of our existing programme in suspension sensing and actuation hardware into cryogenic operation.

Improvements in the LIGO low-frequency band call for new position sensors with a low self-noise. We explore an application of interferometric readout to the LIGO suspensions and seismometers. Compact interferometers have the potential to improve the self-noise of existing LIGO position sensors by two orders of magnitude.

Figures:

Figure 1: Picture of the vacuum tank for tests of the position sensors

Figure 2: BOSEM shadow sensors and actuators

Figure 3: HoQI interferometric sensors

Selected publications:

A compact, large-range interferometer for precision measurement and inertial sensing

Sensors and actuators for the Advanced LIGO mirror suspensions

For more information contact: Sam Cooper, Amit Ubhi, Denis Martynov

Amplifier: interaction
Amplifier: layout
Amplifier: sensitivity

Quantum amplifiers

Quantum noise limits the sensitivity of modern precision measurements, such as observation of gravitational waves and dark matter searches. In order to advance precision measurements, we study quantum phase-insensitive amplifiers that have the potential to improve the performance of optical interferometers.

In our group, we build an active optical system that amplifies signal and noise asymmetrically and improves the signal-to-noise ratio compared to passive optical resonators. We embed a quantum filter with an active medium in the optical cavity to demonstrate the performance of the coupled cavity system with a particular gain.

Figures:

Figure 1: Optomechanical interaction

Figure 2: Photo of the experiment

Figure 3: Quantum noise suppression

Selected publications:

Enhancing the bandwidth of gravitational-wave detectors with unstable optomechanical filters

Converting the signal-recycling cavity into an unstable optomechanical filter to enhance the detection bandwidth of gravitational-wave detectors

For more information contact: Joe Bentley, Jiri (George) Smetana, Amit Ubhi, Teng Zhang, Denis Martynov Haixing Miao

Group

Denis Denis Martynov
Senior Lecturer
Haixing Haixing Miao
Senior Lecturer
Alberto Alberto Vecchio
Prof, Head of Institute
Kazu Kazuhiro Agatsuma
Research staff
Phase cameras
Sam Sam Cooper
Research staff
Seismic isolation
Artemiy Artemiy Dmitriev
Research staff
Optomechanics
Leo Leonid Prokhorov
Research staff
Seismic isolation
Teng Teng Tzang
Research staff
Quantum optics
Joe Joe Bentley
PhD student
Quantum optics
Chiara Chiara Di Fronzo
PhD student
Seismic isolation
Philip Philip Jones
PhD student
Future detectors
Riccardo Riccardo Maggiore
PhD student
Optomechanics
Samuel Samuel Rowlinson
PhD student
Future detectors
George Jiri (George) Smetana
PhD student
Cryogenic silicon
Amit Amit Ubhi
PhD student
Seismic isolation
Tom Rocke Thomas Rocke
Year 4 student
Machine learning
Jake Ward Jake Ward
Year 4 student
Machine learning
John Bryant John Bryant
Research assistant
Ken Dawkings Ken Dawkings
Research assistant
Steve Hately Steve Hately
Research assistant
David Hoyland David Hoyland
Research assistant

Join us

MSc positions:

Every year we offer 3-5 experimental projects for Birmingham Master students.

PhD positions:

Every year we offer 1-2 PhD positions to drive our experimental effort forward. Apply now. The list of available 2021 PhD projects is listed below:

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.

6D seismometer:

An ideal gravitational-wave detector would measure fluctuations of the distance between a set of free masses, i.e. masses with no external forces acting on them. Since it is not possible to have free masses on Earth, test masses are suspended from the ground in the LIGO detectors. This approach allows observation of gravitational waves above 30 Hz but couples ground vibrations at lower frequencies which move test masses through the suspension system. One possible solution to the problem is to suspend test masses from an intermediate platform and actively stabilise its motion using quite inertial sensors. The key challenge is that even state-of-the-art inertial sensors are still not good enough to suppress the coupling of the ground motion to the desired level. In this project, we develop a novel isolation system with an interferometric readout which should reach the requirements. PhD student will learn the basic principles of optical interferometry, inertial isolation, and control theory and develop the novel precision sensors for the LIGO detectors.

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.

Axion interferometer:

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. 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. Axions and axion-like-particles are promising dark matter candidates. PhD student will help build a tabletop optical interferometer to hunt for axion-like-particles and acquire skills in precision measurements, quantum optics, data analysis, control theory, and laser physics.

Postdoc positions:

Three new post-doctoral positions to start in 2021 are available. Advertisements coming soon!

Faculty positions:

No openings at the moment.

Send your questions about jobs to

Alberto Vecchio

Denis Martynov

Haixing Miao