News

By looking for evidence of steering, Bob can check if he and Alice share entanglement, even if the source of light and Alice's detectors are untrustworthy black-boxes (as shown in the image above). Image credit: Alessandro Fedrizzi.

Experiments with entangled photons have led the way in the burgeoning fields of quantum information, communication and computation in the last decade.

Their biggest drawback has always been low photon-detection efficiencies, which has limited their potential applications.

Now, a joint experiment by Australian and US labs has fixed this problem, doubling the previous record in entangled photon detection ratio to 62 per cent, and closing the detection “loophole” in the strange phenomenon of quantum steering.

The experiment was conducted by researchers from the ARC Centre for Engineered Quantum Systems (EQuS) and the ARC Centre for Quantum Computation and Communication Technology (CQC2T) in Australia; and the National Institute of Standards and Technology (NIST) in Boulder, USA.

Austrian physicist Erwin Schrödinger first introduced the term steering in 1935 to highlight the ability of certain quantum particles to influence—or steer—each other no matter how far they are apart.

This striking effect is the result of quantum entanglement—a phenomenon that connects two particles in such a way that changes to one of the particles are instantly reflected in the other—something that Einstein famously described as “spooky action-at-a-distance”.

Steering allows two parties to verify if they have received quantum particles that share this quantum entanglement—even if one of the parties cannot be trusted.

However, if there are any loopholes—which occur due to problems with the experimental design or set-up—the parties will not be able to say that they have conclusively observed quantum steering.

“We overcame the detection loophole—where not all the photons can be detected—by combining a highly-efficient entangled photon source with state-of-the-art photon detectors,” said Dr Marcelo de Almeida from EQuS.

These detectors—called transition edge sensors —were developed by Dr Sae Woo Nam and his team at the National Institute of Standards and Technology.

“The absorption of a single photon in such detectors causes a tiny change in the temperature which is sensed using superconducting effects,” Dr Almeida said.

“Closing the detection loophole requires efficiencies of above 50 per cent.

“The remarkably high efficiency of 62 per cent achieved in our experiment allows us to demonstrate conclusive steering.”

Dr Almeida’s co-authors include PhD students Devin H. Smith, Geoff Gillett, Drs Alessandro Fedrizzi, Till J. Weinhold, and Cyril Branciard, and Professor Andrew G. White from the ARC Centre for Engineered Quantum Systems (EQuS) and the ARC Centre for Quantum Computation and Communication Technology (CQC2T), as well as Professor Howard M. Wiseman from Griffith University, also of CQC2T.

This record-breaking achievement, published in Nature Communications today, brings the researchers a step closer toward achieving even higher detection efficiency levels in the near future.

“If we can achieve 66 per cent, then we could perform secure quantum communication even if one party has untrustworthy equipment. Five years ago I would have thought that was impossible,” said Dr Almeida.

Did you know that by manipulating the use of light in a photograph, you can dramatically affect whether that picture will be spectacular or terrible!

We want you to use your knowledge of light to capture the work, the people, and the facilities of your Centre.

Images submitted to the competition will be used by EQuS in our annual report, website, and other documents. If your image/s contain people, please obtain the names and contact details to ensure we can obtain permission to publish their image.

There will be two categories

•           Best image – winner receives an iPad 2 (16GB Wifi)

•           This is a People’s choice award – winner receives a $250 amazon voucher

To enter

1. Take your photo
2. Email your entry to does97haw@photos.flickr.com – Attach the image to your email and include your name, description of the image, and the node you represent in the body of your email.
   

People’s Choice Award

The people’s choice award is determined by the most popular image. Visit www.flickr.com/photos/equs/ to see all the entries and comment on your favourite.

Eligibility

1. The competition is open to Australian Research Council Centre of Excellence for Engineered Quantum Systems students and postdoctoral researchers.
2. The competition is open from Thursday 15 December 2011 and closes at midnight on Friday 3 February.
3. The decisions are final and no correspondence will be entered into.
4. Photographs and images must be your own work.
5. Photographs and images must not be already in the public domain, submitted to other competitions or used elsewhere in publications, websites etc.
6. Entries without name, description and node will not be eligible.

Physics of Ultra-Cold Quantum Gases, The University of Queensland

In the last fifteen years the trapping and cooling of tiny samples of gases down to temperatures a few billionths of a degree above absolute zero has become routine.  Under these extreme conditions a new state of matter known as a Bose-Einstein condensate (BEC) may form. Associate Professor Davis’ research focuses on studying the non-equilibrium behaviour of BEC’s and in particular how they form from an ordinary gas.  This work provides quantitative insights into the dynamics of phase transitions, relevant to many aspects of nature from the unraveling of DNA to the birth of the universe, but they are still poorly understood.

Matthew initiated and ran a “Quantum Science” seminar series as well as being involved in the Siemens Science Experience. He has a knack for understanding his audience, and gives accessible presentations to a wide range of audiences from colleagues to undergraduate students to the general public. He has also introduced active learning to the lecture room of his first year Physics course.

Source: www.aips.net.au/tall-poppies/qld-tall-poppies/

The mining industry could one day be using quantum-enabled technologies to speed up the mineral exploration process.

Dr Michael J. Biercuk from the ARC Centre of Excellence for Engineered Quantum Systems, along with colleagues in the US, have developed the world’s most sensitive detector of force; a technology that could lead to faster and more accurate sensing for minerals exploration.

Dr Biercuk’s work has also sparked interest in the innovation sector making the finals of the Australian Innovation Challenge Awards, in the Minerals and Energy category.

“The ability to measure tiny forces at a dramatically enhanced speed may spark a new interest in ion-based sensors for applications such as material composition analysis and standoff detection for the mining industry,” explain Dr Biercuk.

The sensor utilises atomic ions trapped using electromagnetic fields.

Electric, magnetic or gravitational fields, such as the magnetic signals generated by iron ore, interact with the sensor causing measurable changes in the metal ions.

The core development was characterising just how sensitive this kind of detector could be. Dr Biercuk’s research showed that it can detect at the scale of the yoctonewton (per square root hertz): a measurement that is a thousand times more sensitive than anything previously possible.

“Yocto” is the smallest prefix used in the Standard International System of Units, making a yoctonewton the smallest unit of force defined in this system.

The work also provides an opportunity to address new challenges arising in materials science and nanotechnology.

The research, part of an effort in quantum-enabled sensing in the ARC Centre of Excellence for Engineered Quantum Systems, demonstrates how cutting-edge science can have a real impact on Australian industries.

“It shows how strategic, long-term research can have unexpected near-term applications,” says Dr Biercuk.

Previously earned Dr. Biercuk the 2011 NMI Prize for excellence in Measurement Science, sponsored by the Federal Government’s Department of Innovation, Industry and Science and Research (DIISR).

The Australian Innovation Challenge is run in association with Shell and is supported by DIISR. Winners will be published in The Australian on December 11.

ARC Engineered Quantum Systems (EQuS) Chief Investigators have broken through a long-standing barrier in diamond science to win the prestigious Macquarie University Research Award in Excellence in Research- Science and Engineering

The team, led by Dr James Rabeau, Associate Professor in Physics at Macquarie University, has demonstrated that nano-diamonds, 5000 times smaller than a human hair, can be isolated and made to emit light.

This breakthrough has made strong impacts worldwide due to the current rush to design and implement new technologies in quantum and biological science that rely on the use of small diamonds.

The team at Macquarie University is part of a national Australia Research Council (ARC) Centre of Excellence for Engineered Quantum Systems (EQuS) focused on quantum-based technologies.

The team is interested in making and measuring small diamonds in order to exploit quantum properties of light and matter, for example using single light particles for quantum communication or information processing.

This work is part of a strategic research focus on quantum-enhanced sensing within the Centre of Excellence.

Other applications of this innovative research lie in the discipline of biology.

The tiny, light emitting diamond particles can potentially be attached to molecules like proteins to track how they move around in a biological environment.

“This is what excites us about our research, we are doing all the very basic fundamental work needed to underpin these new cutting edge applications,” said Dr Rabeau.

The team consists of Mr Carlo Bradac, Dr Torsten Gaebel, Miss Jana Say, Dr Nishen Naidoo, Professor Jason Twamley, Dr Louise Brown, and Dr Andrei Zvyagin.

The National Measurement Institute Prize for Excellence in Measurement Techniques has been awarded to ARC Engineered Quantum Systems (EQuS) Chief Investigator, Dr Michael J. Biercuk.

Dr Michael Biercuk

Dr Biercuk was acknowledged for his collaborative research into sensitive measurements of force.

The research team consisting of Dr Biercuk, the Ion Storage Group and the US National Institute of Standards and Technology, demonstrated it is possible to use trapped atomic ions as extremely sensitive detectors of applied forces and electromagnetic fields.

The researchers were able to measure forces with extraordinary sensitivity – down to the yoctonewton (yN) level. The yoctonewton represents one septillionth of a newton, the unit of force named after physicist Sir Isaac Newton.

Innovation Minister Senator Kim Carr, who announced the award early in September said the award recognised Dr Biercuk’s contribution to science.

“This award recognises Dr Biercuk’s research in the most sensitive measurement of force to date – the yoctonewton,” Innovation Minister Senator Kim Carr.

“This is an incredibly small force – about a million million billion times smaller than the force exerted by a feather lying on a table. The measurement is a thousand times more sensitive than anything previously possible,” Minister Carr said.

This work is part of a strategic research focus on quantum-enhanced sensing within the Centre for Engineered Quantum Systems (EQuS).

It contributes the Centre’s efforts to usher-in a new generation of advanced sensor technologies for scientific and technological applications.

Dr Biercuk said the discovery provides an opportunity to address new challenges in materials science, nanotechnology and industrial sensing.

“By characterising the detector’s sensitivity, a term with technical importance, rather than just the minimum force we could detect, we touched on an important area for industrial applications – the speed with which a measurement can be performed,” Dr Biercuk said.

Dr Biercuk said this has the potential to dramatically improve the speed and efficiency of standoff detection of small forces and fields – for instance geophysical anomalies useful in mineral exploration.

“I am extremely grateful and humbled that this work was deemed significant enough to warrant this distinction, and I’m very pleased that the exciting new field of quantum science is having impacts on a variety of disciplines, including measurement science,” Dr Biercuk said.

The interior of a powerful machine newly installed at The University of Western Australia is not only the coldest place in the State, it is colder by far than anywhere in Antarctica or even in outer space.

In fact, the temperature inside the machine is less than eight thousandths of a degree above the coldest temperature possible (minus 273 degrees Celcius).

The machine, a $400,000 BlueFors dry dilution refrigerator manufactured in Finland and filled with $50,000 worth of Helium 3 gas from the United States, is a key piece of equipment to be used by Australian Laureate Fellow Winthrop Professor Mike Tobar and his team.

Based in UWA’s School of Physics, Professor Tobar’s group in the Australian Research Council Centre of Excellence in Engineered Quantum Systems (EQuS) will use the machine to cool devices down to phenomenally low temperatures to examine their behaviour.

In doing so, they will better understand the sophisticated workings of quantum mechanics, the basics of which have enabled technology we now take for granted: computers and the internet.

“The strangeness of quantum mechanics could be used as a new and untapped resource,” Professor Tobar said.

“To use a simple analogy: where once we were looking through a pea-soup fog, now we’ve got a clear blue sky,” Professor Tobar said.

“We’ll be able to engineer complex, multi-component, quantum systems for new science and new applications.  Long-standing questions in fundamental physics will be addressed; cross-disciplinary scientific advances will be made linking quantum physics with engineering, chemistry, and biology; and sophisticated technologies will be developed for 21^st century Australian industries.”

The BlueFors refrigerator, the only one of its kind in the southern hemisphere, is the most powerful ever built by the Finnish company whose co-founder Dr Rob Blaauwgeers accompanied it to UWA and supervised the installation.

MEDIA REFERENCE

Winthrop Professor Mike Tobar (+61 8)  6488 3443  /  (+61 4) 04 872 944

(UWA School of Physics)

Sally-Ann Jones (UWA Public Affairs)                           (+61 8)  6488 7975  /  (+61 4) 20 790 098