Exploring quantum aspects of gravitational-wave detectors
Lead Research Organisation:
University of Birmingham
Department Name: School of Physics and Astronomy
Abstract
Einstein's general theory of relativity is currently our fundamental theory about spacetime and matter. It is an elegant theory and explains the observed astronomical phenomena very well. It also predicts the existence of gravitational waves, which are ripples in spacetime propagating at the speed of light. By detecting gravitational waves created by cosmic objects such as black holes, we aim to open a new window on the Universe through gravitational-wave astronomy. The efforts for detecting gravitational waves started almost half a century ago and have turned out to be one of the most challenging endeavours in experimental science, because the amplitudes of the expected waves are extremely small. The state-of-the-art approach for gravitational wave detection is using kilometre-scale laser interferometer with tens-of-kilograms mirrors as test masses. Several such interferometric detectors have been built around the world. Their sensitivity is so great that, even though they use macroscopic components, their performance is affected and limited by tiny quantum effects. The proposed research is aiming at better understanding the various quantum aspects of gravitational wave detectors. On the one hand, this leads to new approaches to overcome the quantum-limits of current detectors, which is an essential step for realizing the ultimate goal of gravitational-wave astronomy. On the other hand, it opens up the possibility to explore quantum behaviours of macroscopic objects in a new regime.
Publications
Miao H
(2017)
Towards the Fundamental Quantum Limit of Linear Measurements of Classical Signals.
in Physical review letters
Miao H
(2018)
Towards the design of gravitational-wave detectors for probing neutron-star physics
in Physical Review D
Miao Haixing
(2017)
Towards the Design of Gravitational-Wave Detectors for Probing Neutron-Star Physics
in ArXiv e-prints
Töyrä D
(2017)
Multi-spatial-mode effects in squeezed-light-enhanced interferometric gravitational wave detectors
in Physical Review D
Description | Advanced gravitational-wave detectors have made breakthrough discoveries by directly detecting gravitational waves from compact binaries, including binary black holes and neutron stars. These discoveries have confirmed the validation of Einstein's general theory of relativity in the strong gravity regime near the vicinity of black hole horizon, and have revolutionized our understanding of neutron stars with the joint electromagnetic observations. In the heart of the advanced detectors, there are kilometer scale Michelson-type laser interferometers, and they are extremely sensitive scientific instruments. It turns out that the quantum nature of light starts to play a significant role in constraining the detector sensitivity. Quantum techniques, e.g., the squeezed state of light, have been studied and implemented for enhancing the sensitivity. The objectives of this project are to (i) study a new active quantum optomechanical filter for improving the detection bandwidth, (ii) understand the fundamental quantum limit of laser interferometers, and (iii) explore the quantum measurement techniques developed by the gravitational-wave community for studying the quantum behaviors of macroscopic objects. The key findings go as follows: For the first objective, we found that the optomechanical filter can improve the detector sensitivity around kHz for detecting signals from binary neutron star mergers [Phys. Rev. D 98, 044044 (2018)]. The key challenge is to reduce the thermal noise from the mechanical oscillator in the optomechanical filter, which requires cryogenic operation. By collaborating with the Caltech group, we found that embedding the optomechanical filter in a parity-time symmetric configuration allows us to operate the system in a stable regime rather than being unstable in the early-proposed configuration [Phys. Rev. D 103, 122001 (2021)]. For the second objective, we first derived the general Heisenberg uncertainty relation for continuous linear quantum measurements [Phys. Rev. A 95, 012103 (2017)]. Using this result, we were able to obtain the general condition for achieving the fundamental quantum limit in laser interferometric gravitational-wave detectors [Phys. Rev. Lett. 119, 050801 (2017)], which is the dream result of this proposal. In the ideal scenario, the only limit to the detector sensitivity comes from the quantum fluctuation of the optical power inside the cavity, which can be significantly enhanced by using the squeezed state of light or coherent optical feedback. The ultimate limit arises from the optical loss inside the detector [Phys. Rev. X 9, 011053 (2019)]. This understanding allows us to have a unified picture of different quantum techniques for improving the detector sensitivity in the quantum regime. For the third objective, we studied the gravitational aspect of the macroscopic objects. We proposed the use of two optomechanical devices located nearby to explore the quantum nature of gravity [Phys. Rev. A 101, 063804 (2020), Quantum Sci. Technol. 6, 045014 (2021)]. If gravity were quantum, the optical fields inside the two cavities will be quantum correlated. By detecting such a correlation we will be able to test some classical models of gravity, which claims that there will be no gravity-induced quantum correlations. Our finding provides a new alternative path to study the quantum aspect of gravitational interaction in the Newtonian limit with tabletop experiments. In conclusion, we have achieved the initial objectives of the proposal. The strong supports from the Ernest Rutherford Fellowship have made such an outcome possible. |
Exploitation Route | There are several ongoing experiments that are trying to test the proposed ideas mentioned in the key findings. The understanding of the fundamental quantum limit provides a unified framework for implementing quantum techniques to improve the detector sensitivity. This will provide guideline in the design of next-generation gravitational-wave observatories. |
Sectors | Education Other |
Description | Birmingham Fellow (permanent faculty position) |
Amount | |
Organisation | University of Birmingham |
Sector | Academic/University |
Country | United Kingdom |
Start | 03/2016 |
Description | Birmingham-Beijing Normal University Instrumentation Fund |
Amount | £269,638 (GBP) |
Organisation | Beijing Normal University |
Sector | Academic/University |
Country | China |
Start | 03/2020 |
End | 12/2020 |
Description | Enhancing gravitational wave detector sensitivity and bandwidth for astronomy |
Amount | $1,097,000 (AUD) |
Funding ID | DP170104424 |
Organisation | Australian Research Council |
Sector | Public |
Country | Australia |
Start | 01/2017 |
End | 12/2021 |
Description | Phase-insensitive amplifier for quantum measurements |
Amount | £260,000 (GBP) |
Funding ID | EP/V048872/1 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 01/2021 |
End | 12/2022 |
Description | Quantum-enhanced interferometry for new physics |
Amount | £1,587,727 (GBP) |
Funding ID | ST/T006609/1 |
Organisation | Science and Technologies Facilities Council (STFC) |
Sector | Public |
Country | United Kingdom |
Start | 12/2020 |
End | 04/2025 |
Description | The Royal Society International Exchanges Scheme |
Amount | £12,000 (GBP) |
Funding ID | IEC\NSFC\170345 |
Organisation | The Royal Society |
Sector | Charity/Non Profit |
Country | United Kingdom |
Start | 03/2018 |
End | 03/2019 |
Description | LIGO Scientific Collaboration |
Organisation | LIGO Scientific Collaboration |
Country | United States |
Sector | Academic/University |
PI Contribution | I have been working on different approaches to improving quantum-limited sensitivity of advanced gravitational-wave detectors. My research outcome provides direct inputs to current R&D of techniques for both near-term upgrade of current detectors and building the next-generation gravitational-wave observatories. |
Collaborator Contribution | They provide complimentary sets of expertise to my research. For example, my theoretical analysis is focusing on experimental setups that my partners are working on, and their feedback is essential to my research. |
Impact | Please refer to the publications with LIGO Scientific Collaboration as the author list. The most significant output is the recent breakthrough discovery of gravitational waves from merging of binary black holes. |
Description | LIGO Scientific Collaboration |
Organisation | LIGO Scientific Collaboration |
Country | United States |
Sector | Academic/University |
PI Contribution | I have been working on different approaches to improving quantum-limited sensitivity of advanced gravitational-wave detectors. My research outcome provides direct inputs to current R&D of techniques for both near-term upgrade of current detectors and building the next-generation gravitational-wave observatories. |
Collaborator Contribution | They provide complimentary sets of expertise to my research. For example, my theoretical analysis is focusing on experimental setups that my partners are working on, and their feedback is essential to my research. |
Impact | Please refer to the publications with LIGO Scientific Collaboration as the author list. The most significant output is the recent breakthrough discovery of gravitational waves from merging of binary black holes. |
Description | A unified framework for improving quantum-limited detector sensitivity |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | This is a talk that I gave at Amaldi 12 Gravitational-Wave Conference held at Pasadena California. This is one of the largest international conference on gravity-related research. I talked about a unified framework for improving quantum-limited sensitivity of gravitational-wave detectors. This is based upon the recent breakthrough understanding of fundamental quantum limit of detector sensitivity. The audiences showed great interests to the topic, and asked many detailed questions after the talk. |
Year(s) Of Engagement Activity | 2017 |
URL | http://amaldi12.org |
Description | An interview by China Global Television Network |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | On March 14, 2017, I was interviewed by China Global Television Network (formerly CCTV International) to comment on Steven Hawking's life and legacy. |
Year(s) Of Engagement Activity | 2017 |
URL | https://www.youtube.com/watch?v=FzAvyDiFalw |
Description | CCTV America Interview |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | I was interviewed by CCTV America to report on the breakthrough discovery of gravitational waves by LIGO. |
Year(s) Of Engagement Activity | 2016 |
URL | https://www.youtube.com/watch?v=lrVfHStGVlU |
Description | Conditional Frequency Dependent Squeezing via EPR Entanglement |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | This is a talk given at the LSC-VIRGO Collaboration September Meeting in Geneva, where I presented an new idea of improving gravitational-wave detector sensitivity based upon quantum entanglement. |
Year(s) Of Engagement Activity | 2017 |
Description | Conditional frequency dependent squeezing via EPR entanglement |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | This is a talk that I gave at the largest annual meeting of LIGO Scientific Collaboration and VIRGO Collaboration which was held at CERN Geneva. I talked about a new idea of improving the quantum-limited sensitivity of advanced gravitational-wave detectors by using the famous Einstein-Podolsky-Rosen quantum entanglement. |
Year(s) Of Engagement Activity | 2017 |
URL | http://www.et-gw.eu/index.php/news/119-lsc-virgo-meeting-2017 |
Description | Design Concepts for High-Frequency Gravitational Wave Detectors |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | This is an invited talk at the KITPC Workshop on Gravitational Waves 2018 in Beijing. The audiences are international colleagues in the gravitational-wave community. |
Year(s) Of Engagement Activity | 2018 |
URL | http://2018gw.csp.escience.cn/ |
Description | Fundamental Quantum Limit of Gravitational-wave Detectors |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Other audiences |
Results and Impact | This is a talk presented in the 9th Nottingham Symposium on Quantum Systems held by the University of Nottingham. The audiences are colleagues from the University of Nottingham. |
Year(s) Of Engagement Activity | 2017 |
Description | Fundamental quantum limit of gravitational-wave detectors |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Postgraduate students |
Results and Impact | This is an invited talk that I gave at 9th Nottingham Symposium on Quantum Systems which was held in University of Nottingham. |
Year(s) Of Engagement Activity | 2017 |
Description | GWADW 2016 |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | This is a workshop on advanced gravitational-wave detectors. I have been actively involved in group discussions about techniques for improving quantum-limited detector sensitivity. |
Year(s) Of Engagement Activity | 2016 |
URL | https://agenda.infn.it/conferenceDisplay.py?confId=10512 |
Description | Gravitational-wave Astronomy and Quantum-limited Instruments |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Postgraduate students |
Results and Impact | This is a talk given at Tianqin Research Centre in the Sun Yat-Sen University. I gave an overview of the research in our Insititute for Gravitational-Wave Astronomy at Birmingham. |
Year(s) Of Engagement Activity | 2017 |
Description | Gravitational-wave astronomy and quantum-limited instruments |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Postgraduate students |
Results and Impact | This is a talk that I gave at the Tianqin Research Centre in the Sun Yat-Sen University (SYSU). It provided an overview of research activities of Birmingham Institute of Gravitational Wave Astronomy, and aimed at establishing collaborations between Birmingham and SYSU which hosts a strong gravitational-wave group. |
Year(s) Of Engagement Activity | 2017 |
Description | Interview for the breakthrough discovery of merging binary neutron stars |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Media (as a channel to the public) |
Results and Impact | I was interviewed by the media of University of Birmingham to comment on the breakthrough discovery of binary neutron stars, which marks the dawn of multi-messenger astronomy. |
Year(s) Of Engagement Activity | 2017 |
URL | https://www.birmingham.ac.uk/news/latest/2017/10/Scientists-celebrate-first-direct-observation-of-co... |
Description | LVC Meeting September 2016 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | I gave a talk to report on the fundamental quantum limit to the sensitivity of gravitational-wave detectors. This is one of the key topics proposed in this funding award. |
Year(s) Of Engagement Activity | 2016 |
URL | http://einstein.astro.gla.ac.uk/lvc2016/ |
Description | LVC meeting September 2016 |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Postgraduate students |
Results and Impact | I gave a tutorial on future advanced gravitational-wave detectors to postgraduate students. This is a part of the LIGO Academic Affairs Council (LAAC) tutorials to inform students in the collaboration of advanced topics. |
Year(s) Of Engagement Activity | 2016 |
URL | http://einstein.astro.gla.ac.uk/lvc2016/ |
Description | Laser Interferometric Gravitational Wave Detectors-Where Gravity Meets Quantum |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Postgraduate students |
Results and Impact | I was invited to give a seminar on quantum aspects of laser interferometric gravitational wave detectors at the Quantum Engineering Technology Labs in the University of Bristol. |
Year(s) Of Engagement Activity | 2019 |
Description | Optomechanics for Gravity |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Other audiences |
Results and Impact | This is a talk presented at The British Optomechanical Research Network workshop organised by University of Nottingham. I provided an overview talk on how to study gravitational physics using optomechanics/ |
Year(s) Of Engagement Activity | 2019 |
Description | Path Towards kHz Gravitational-Wave Astronomy |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | This is a talk given at the China-UK GREAT Network Workshop organised by University of Glasgow. In the talk, I presented ideas to improve the sensitivity of gravitational-wave detectors at kHz for probing neutron star physics. |
Year(s) Of Engagement Activity | 2019 |
Description | Prospects of Improving Detector at Low Frequencies and High Frequencies |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | This is an invited talk given at the LSC-VIRGO Collaboration March Meeting in Sonoma State University, which is the largest annual meeting of the collaboration. |
Year(s) Of Engagement Activity | 2018 |
URL | http://ligo.sonoma.edu/ |
Description | Quantum Correlations of Light Mediated by Gravity |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Other audiences |
Results and Impact | This is a talk presented at the Macroscopic quantum superpositions (MaQS) worshop organised by Imperial College London. I presented an approach to probing the quantum nature of gravity using optomechanical devices. |
Year(s) Of Engagement Activity | 2019 |
URL | https://www.imperial.ac.uk/quantum-engineering-science-technology/maqs-workshop/ |
Description | Quantum Limits of Laser Interferometric Gravitational Wave Detectors |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Postgraduate students |
Results and Impact | This is a seminar given at Tsinghua State Key Laboratory of Low-Dimensional Quantum Physics. |
Year(s) Of Engagement Activity | 2018 |
Description | Quantum Techniques in Laser interferometric Gravitational Wave Detectors |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Other audiences |
Results and Impact | This is a talk given at the Workshop on Quantum Sensors for Fundamental Physics held in Oxford. The audiences are colleagues from both quantum measurement and particle physics community. |
Year(s) Of Engagement Activity | 2018 |
Description | Testing quantum nature of Newtonian gravity with optomechanics |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Postgraduate students |
Results and Impact | In this talk, I discussed the use of optomechanics for testing the quantum nature of gravity in the strong gravity seminar organised by the Perimeter Institute in Canada. This seminar was delivered via Zoom. |
Year(s) Of Engagement Activity | 2021 |
Description | Towards the Design of Gravitational-wave Detectors for Neutron-star Physics |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Postgraduate students |
Results and Impact | This is a seminar given at Tsinghua University Centre for Astrophysics (THCA), where I reported a new design of gravitational-wave detector for probing neutron star physics. |
Year(s) Of Engagement Activity | 2017 |
Description | Towards the design of gravitational-wave detectors for neutron-star physics |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Postgraduate students |
Results and Impact | This is a seminar that I gave at the Tsinghua University Centre for Astrophysics (THCA). It was about a new conceptual design of a gravitational-wave detector for probing new physics during the merger phase of binary neutron stars. |
Year(s) Of Engagement Activity | 2017 |