Business Web Sites
Daily BulletinHoliday Centre

The Conversation

  • Written by David Blair, Director, WA Node of the ARC Centre of Excellence for Gravitational Wave Discovery, and the Australian International Gravitational Research Centre, University of Western Australia
image

The first direct detection of gravitational waves, a phenomenon predicted by Einstein’s 1915 general theory of relativity, was reported by scientists in 2016.

Armed with this “discovery of the century”, physicists around the world have been planning new and better detectors of gravitational waves.

Physicist Professor Chunnong Zhao and his recent PhD students Haixing Miao and Yiqiu Ma are members of an international team that has created a particularly exciting new design for gravitational wave detectors.

The new design is a real breakthrough because it can measure signals below a limit that was previously believed to be an insurmountable barrier. Physicists call this limit the standard quantum limit. It is set by the quantum uncertainty principle.

The new design, published in Nature magazine this week, shows that this may not be a barrier any longer.

Using this and other new approaches may allow scientists to monitor black hole collisions and “spacequakes” across the whole of the visible universe.

How gravitational wave detectors work

Gravitational waves are not vibrations travelling through space, but rather vibrations of space itself. They have already told us about an unexpectedly large population of black holes. We hope that further study of gravitational waves will help us to better understand our universe.

But the technologies of gravitational wave detectors are likely to have enormous significance beyond this aspect of science, because in themselves they are teaching us how to measure unbelievably tiny amounts of energy.

Gravitational wave detectors use laser light to pick up tiny vibrations of space created when black holes collide. The collisions create vast gravitational explosions. They are the biggest explosions known in the universe, converting mass directly into vibrations of pure space.

It takes huge amounts of energy to make space bend and ripple. Our detectors – exquisitely perfect devices that use big heavy mirrors with scarily powerful lasers – must measure space stretching by a mere billionth of a billionth of a metre over the four kilometre scale of our detectors. These measurements already represent the smallest amount of energy ever measured.

But for gravitational wave astronomers this is not good enough. They need even more sensitivity to be able to hear many more predicted gravitational “sounds”, including the sound of the moment the universe was created in the big bang.

This is where the new design comes in.

A spooky idea from Einstein

The novel concept is founded on original work from Albert Einstein.

In 1935 Albert Einstein and co-workers Boris Podolsky and Nathan Rosen tried to depose the theory of quantum mechanics by showing that it predicted absurd correlations between widely spaced particles.

Einstein proved that if quantum theory was correct, then pairs of widely spaced objects could be entangled like two flies tangled up in a spider’s web. Weirdly, the entanglement did not diminish, however far apart you allowed the objects to move.

Einstein called entanglement “spooky action at a distance”. He was sure that his discovery would do away with the theory of quantum mechanics once and for all, but this was not to be.

Since the 1980s physicists have demonstrated time and again that quantum entanglement is real. However much he hated it, Einstein’s prediction was right and to his chagrin, quantum theory was correct. Things at a distance could be entangled.

Today physicists have got used to the “spookiness”, and the theory of entanglement has been harnessed for the sending of secret codes that cannot be intercepted.

Around the world, organisations such as Google and IBM and academic laboratories are trying to create quantum computers that depend on entanglement.

And now Zhao and colleagues want to use the concept of entanglement to create the new gravitational wave detector’s design.

A new way to measure gravitational waves

The exciting aspect of the new detector design is that it is actually just a new way of operating existing detectors. It simply uses the detector twice.

One time, photons in the detector are altered by the gravitational wave so as to pick up the waves. The second time, the detector is used to change the quantum entanglement in such a way that the noise due to quantum uncertainty is not detected.

The only thing that is detected is the motion of the distant mirrors caused by the gravitational wave. The quantum noise from the uncertainty principle does not appear in the measurement.

To make it work, you have to start with entangled photons that are created by a device called a quantum squeezer. This technology was pioneered for gravitational wave astronomy at Australian National University, and is now an established technique.

Like many of the best ideas, the new idea is a very simple one, but one that took enormous insight to recognise. You inject a miniscule amount of squeezed light from a quantum squeezer, and use it twice!

Around the world physicists are getting ready to test the new theory and find the best way of implementing it in their detectors. One of these is the GEO gravitational wave detector at Hannover in Germany, which has been a test bed for many of the new technologies that allowed last year’s momentous discovery of gravitational waves.

Authors: David Blair, Director, WA Node of the ARC Centre of Excellence for Gravitational Wave Discovery, and the Australian International Gravitational Research Centre, University of Western Australia

Read more http://theconversation.com/physicists-use-einsteins-spooky-entanglement-to-invent-super-sensitive-gravitational-wave-detector-77822


The Conversation

Politics

Prime Minister - Step up in drought budget support

Drought-hit farmers, small businesses and rural towns are set for an immediate cash injection to keep stock fed and watered, keep businesses open, keep locals in work and pump funds into local eco...

Scott Morrison - avatar Scott Morrison

David Littleproud MP interview with Tom Connell

Interview with Tom Connell – Sky News NewsDay   The Coalition’s latest drought support package   TOM CONNELL: David Littleproud, thanks for your time. We've got this drought package going throug...

Tom Connell - avatar Tom Connell

Prime Minister Address Tom Hughes Oration Dinner

Thank you very much, Julian, for that very kind introduction.  It was very generous. Thank you very much for those words.  It's great to be here with you.  I'm here today to give the vote of thank...

Scott Morrison - avatar Scott Morrison

Business News

Decathlon Group: Global sporting brand opens its third store

International sporting brand Decathlon today opened its much anticipated third store in Victoria.    Located at 405 Boundary Road, Moorabbin Airport, the store extends the brand’s footprint across V...

Tess Sanders Lazarus - avatar Tess Sanders Lazarus

How to grow your construction business into an empire

If construction is the business that you are in and you are looking to make the transition from being a small operator to a major player, you are going to have to ask some tough questions. And qui...

News Company - avatar News Company

Acciona And Surfing Australia Partnership

Acciona Ambassador and 2020 World Surf League (WSL) Women’s World Tour rookie Isabella Nichols with Bede Noonan, Managing Director of Acciona Geotech at today's launch. CASUARINA/NSW (N...

Blainey Woodham - avatar Blainey Woodham

Travel

Planning a High School Educational Trip: Useful Pointers to Keep in Mind

Planning and managing an educational trip is not an easy job for teachers, especially if the group consists of high school teenagers! At the same time, high schoolers are also at an age where they...

News Company - avatar News Company

Why Do So Many Brits Travel To Australia?

Australia is one of the most popular destinations for travellers around the world, but maybe none more so that British travellers. Hundreds of thousands of Brits leave the UK on a yearly basis to sw...

News Company - avatar News Company

Hen Weekends Abroad- Top 5 cities for a perfect hen party

All good things end. It’s not to say that marriage shouldn’t be treated as something absolutely exceptional - on the contrary. Unfortunately though, once we find the person we couldn’t imagine our l...

Monika Rose - avatar Monika Rose

ShowPo