Scientists discover how to smash quantum limits

02 Jul 2020 | 4 mins

Scientists from The University of Western Australia’s Centre of Excellence for Gravitational Wave Discovery (OzGrav) are part of a global team of researchers that has made a surprising discovery, working out how to break quantum limits. The research was published today in the prestigious Nature journal.

A quantum limit comes about from the interaction between light and a test mass, and breaking this limit, just like breaking the sound barrier, once seemed impossible.

The scientists surpassed the limit in their quest to build better gravitational wave detectors using squeezed light technology on 40kg test masses in LIGO detectors.

The technology was pioneered by the Australian National University and refined at Massachusetts Institute of Technology, which led to the development of the squeezed light apparatus at the LIGO and the groundbreaking result.

Gravitational wave detectors are the most precise measurement devices ever built, and the result shows they are now poised to see and exploit the effects of quantum physics, which governs the smallest objects in the universe, on human-sized objects like their 40kg test masses.

UWA physicist Dr Carl Blair, who was part of the team to make the discovery said discovering how to break quantum limits was significant for physics and science.

“It’s amazing to think that sitting in the control room at LIGO, by manipulating some controls on a computer you can manipulate the quantum noise of a 40 kg mirror,” he said.

“We were able to break the limit doing something very mysterious - squeezing the quantum vacuum,” he said.

“Now that it has been proven possible, this new technology can be used to build more sensitive machines to explore the Universe.

“In breaking this limit, we are now entering a world where quantum limits on measurements can be routinely surpassed.”

Scientist Dr Xu Chen, also from UWA, said OzGrav and their collaborators were able to smash through the quantum noise barrier of gravitational-wave detectors. “At UWA, we aim to improve the sensitivity further with a white-light cavity.

This works best at higher frequencies where we can see more binary neutron stars colliding,” she said.

Australian National University PhD student Nutsinee Kijbunchoo and postdoctoral fellow Dr Terry McRae spent more than a year at the LIGO sites building and commissioning the squeezed light system that lead to the quantum physics breakthrough.

FURTHER INFORMATION:

The ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav) is funded by the Australian Government through the Australian Research Council Centres of Excellence funding scheme. OzGrav is a partnership between Swinburne University of Technology (host of OzGrav headquarters), the Australian National University, Monash University, University of Adelaide, the University of Melbourne, and the University of Western Australia, along with other collaborating organisations in Australia and overseas.

LIGO is funded by NSF and operated by Caltech and MIT, which conceived of LIGO and led the Initial and Advanced LIGO projects. Financial support for the Advanced LIGO project was led by the NSF with Germany (Max Planck Society), the U.K. (Science and Technology Facilities Council) and Australia (Australian Research Council-OzGrav) making significant commitments and contributions to the project. Nearly 1300 scientists from around the world participate in the effort through the LIGO Scientific Collaboration, which includes the GEO Collaboration. A list of additional partners is available at https://my.ligo.org/census.php.

The Virgo Collaboration is currently composed of approximately 350 scientists, engineers, and technicians from about 70 institutes from Belgium, France, Germany, Hungary, Italy, the Netherlands, Poland, and Spain. The European Gravitational Observatory (EGO) hosts the Virgo detector near Pisa in Italy and is funded by Centre National de la Recherche Scientifique (CNRS) in France, the Istituto Nazionale di Fisica Nucleare (INFN) in Italy, and Nikhef in the Netherlands. A list of the Virgo Collaboration members can be found at http://public.virgo-gw.eu/the-virgo-collaboration

The Kamioka Gravitational Wave Detector (KAGRA), formerly the Large Scale Cryogenic Gravitational Wave Telescope (LCGT), is a project of the gravitational wave studies group at the Institute for Cosmic Ray Research (ICRR) of the University of Tokyo. It will be the world's first gravitational wave observatory in Asia, built underground, and whose detector uses cryogenic mirrors. The design calls for an operational sensitivity equal to, or greater, than LIGO. The project is led by Nobelist Takaaki Kajita who had a major role in getting the project funded and constructed.

Media references

Dr Carl Blair , UWA Postdoctoral fellow, 0406 166 236 
Dr Xu Chen, UWA Postdoctoral fellow, 0402 844 072
Jess Reid, UWA Media and PR Adviser, 08 6488 6876

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