Gravitational Wave Astronomy at the University of Birmingham, STFC Equipment Call 2018

Lead Research Organisation: University of Birmingham
Department Name: School of Physics and Astronomy


On September 14, 2015 LIGO directly detected gravitational waves (GWs), completing the quest for the experimental confirmation of a fundamental prediction of Einstein's theory of general relativity.
With this observation, followed by another five signals, we have shown the existence of heavy stellar-mass black holes, and established that binary black holes can form and merge within a Hubble time. On August 17, 2017, we detected GW170817, the first observed coalescence of a binary neutron star. The LIGO-VIRGO low-latency 3-dimensional sky localisation enabled the discovery of its optical counterpart and the identification of its host galaxy, which was followed by a remarkable observational campaign of the post-merger remnant across the full electromagnetic spectrum

GW observations are already transforming our understanding of black holes, neutron stars, their formation and evolution, the state of matter in the most extreme conditions, and the behaviour of dynamical, strong-field gravity in previously untested regimes. However, this knowledge will be even further advanced once the sensitivity of the GW detectors is improved. Currently, the LIGO sensitivity is diminished by technical control noises below 30 Hz. At higher frequencies, the sensitivity is limited by the quantum noises which are triggered by fundamental vacuum fluctuations of electromagnetic fields. If no new technology is developed, future GW observatories, such as the Einstein Telescope in Europe or LIGO Voyager and Cosmic Explorer in the U.S., will face similar limits. In this proposal, we seek to experimentally demonstrate two new technologies: a 6 degree-of-freedom (6D) seismometer and a quantum filter. In the future, 6D seismometers and quantum filters will increase the signal-to-noise ratio of individual GW sources, expanding the astrophysical reach of the detectors, and will vastly augment the amount of time the source is in band, with spectacular consequences for electromagnetic follow-up campaigns.

Planned Impact

In terms of academic impact, the immediate beneficiaries include the UK (and international) astronomy and physics community, extending far beyond the applicant group. Research in gravitational-wave astronomy is expected to continue to transform our understanding of the Universe, including information on the properties of neutron stars and black holes, and the behaviour of gravity in extreme conditions; in the long-term it will offer a new window on the very early Universe, when it is was a fraction of a second old. This will benefit the widest astronomy/astrophysics community, internationally.

With regard to societal impact, astrophysics and black holes, are exciting areas and reliably excellent topics for public outreach. We have directly experienced the broad high-impact generated by the direct detection of gravitational waves and the first multi-messenger observation of a double neutron star coalescence. New activities have been flourishing and we expect this to continue and increase in the future. This progress should also help revitalise public interest in science as a whole at a time when economic pressure could potentially shrink investment in science in general. Our public engagements activities have already generated new online media for education and outreach, such as interactive computer games. They have attracted considerable attention and we have been developing these games for tablets and other platforms, which are reaching an even wider audience.

Work that we have carried out in the experimental area has already provided direct benefit to UK industry, such as local SMEs with contacts for about £1M. We are developing new quantum technologies and inertial sensors that have the potential of a variety of industrial applications for quantum systems, new gravity-gradient sensors and integrated system models for navigation systems. Although designed for interferometric GW detectors, the proposed 6D isolation system can also reduce vibrational noise, that couples though aliasing and Doppler-shifting, in atom- interferometer instruments such as MIGA. Our analysis of the inertial isolation performance is directly applicable to other laboratory experiments that require a low acceleration environment, from space-borne accelerometer development, to measurements of small forces such as inverse-square-law tests. The quantum filter IS being developed specifically for GW detectors, but can also be used to generate squeezed states of light by means of amplitude and phase quadrature conversion of the laser field by the mechanical oscillator. Squeezed states of light have already found applications in quantum communication and continuous-variable quantum computing. For instance, the Xanadu photonic quantum computer design uses squeezed light to allow continuous variable quantum computing for applications in machine learning, chemistry, finance and optimisation. We plan to carry out a dedicated programme of knowledge transfer and industrialisation together with the Birmingham Quantum Hub and NPL.

Of course, the training which post-doctoral research assistants and PhD students receive within our grant-funded programme is also of much wider benefit to the academic and non-academic communities. For example many of our students and post-doctoral researchers have secured high-profile jobs in the high-tech and data-intensive sectors.


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