Centre Updates

New photonic chip promises more robust quantum computers

Scientists have developed a topological photonic chip to process quantum information, promising a more robust option for scalable quantum computers.

The research team, led by RMIT University’s Dr Alberto Peruzzo, has for the first time demonstrated that quantum information can be encoded, processed and transferred at a distance with topological circuits on the chip. The research is published in Science Advances.

The breakthrough could lead to the development of new materials, new generation computers and deeper understandings of fundamental science.

In collaboration with scientists from the Politecnico di Milano and ETH Zürich, the researchers used topological photonics – a rapidly growing field that aims to study the physics of topological phases of matter in a novel optical context – to fabricate a chip with a ‘beamsplitter’ creating a high precision photonic quantum gate.

“We anticipate that the new chip design will open the way to studying quantum effects in topological materials and to a new area of topologically robust quantum processing in integrated photonics technology,” says Peruzzo, Chief Investigator at the ARC Centre of Excellence for Quantum Computation and Communication Technology (CQC2T) and Director, Quantum Photonics Laboratory, RMIT.

“Topological photonics have the advantage of not requiring strong magnetic fields, and feature intrinsically high-coherence, room-temperature operation and easy manipulation” says Peruzzo.

“These are essential requirements for the scaling-up of quantum computers.”

Read paper here

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Making light work of quantum computing

Light may be the missing ingredient in making usable quantum silicon computer chips, according to an international study featuring #CQC2T Professor Timothy Ralph from the University of Queensland.

The team has engineered a silicon chip that can guide single particles of light – photons – along optical tracks, encoding and processing quantum-bits of information known as ‘qubits’.

The experiment, conducted primarily at the University of Bristol, proved that it is possible to fully control two qubits of information within a single integrated silicon chip.

A surprising result of the experiment is that the quantum computing machine has become a research tool in its own right.

“The device has now been used to implement several different quantum information experiments using almost 100,000 different reprogrammed settings,” Professor Ralph said.

“This is just the beginning; we’re just starting to see what kind of exponential change this might lead to.”

The research has been published in Nature Photonics. (DOI: 10.1038/s41566-018-0236-y)

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CQC2T physicist Dr Rose Ahlefeldt named ACT Scientist of the Year

Congratulation to CQC2T researcher Dr Rose Ahlefeldt from the Australian National University (ANU) who was named ACT Scientist of the Year.

Dr Ahlefeldt's research is trying to find the right materials to build the quantum memories needed for quantum computers. These computers could solve some of the world's "impossible" problems.

"I am trying to understand how the atoms in the crystals interact with the light, so I can choose the right materials to make better quantum memories." says Dr Ahlefeldt.

"One day we're going to build quantum computers that can solve problems that are impossible for our current computers. Researchers have already identified many uses for these computers, including enhancing artificial intelligence establishing secure communications and eventually building a quantum internet."

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Hundreds of school students get exclusive insights into the world of quantum

200 primary and secondary school students got a rare peek into what life as a scientist could be like, as Professor Michelle Simmons opened the doors of the Centre for Quantum Computation and Communication Technology (CQC2T) ahead of National Science Week.

When Scientia Professor Michelle Simmons became Australian of the Year 2018, her acceptance speech touched on themes that resonated with many school students and teachers: her encouragement of all young people to pursue what they love, to set their sights high, to tackle the hardest challenges in life and to be the creators – not just the users – of technology. Following the ceremony – and numerous subsequent speech invites from schools across Australia – Professor Simmons and her team decided to open the doors of the Centre for Quantum Computation and Communication Technology for one full day, to offer students the opportunity to see the team’s ground-breaking research in action – a first in the centre’s history.

Professor Simmons said the goal of the day was to open the students’ minds to the possibilities that a career in STEM offers. “When I was younger, I got to see a fabrication plant in the US, and observed how they make semi-conductor chips. It completely opened my mind to the world of possibility that was out there. I remember thinking that all children should see this. “So here we are in Australia, we've got this great facility of building chips in-house, so I'm hoping we opened the students’ eyes to what's out there, to all the kind of jobs they can have, and just get them excited by science.”

Tuning into quantum: scientists unlock signal frequency control of precision atom qubits

CQC2T scientists, led by Prof Michelle Simmons, have achieved a new milestone in their approach to creating a quantum computer chip in silicon, demonstrating the ability to tune the control frequency of a qubit by engineering its atomic configuration.

The team from UNSW Sydney successfully implemented an atomic engineering strategy for individually addressing closely spaced spin qubits in silicon. The scientists created engineered phosphorus molecules with different separations between the atoms within the molecule allowing for families of qubits with different control frequencies. Each molecule could then be operated individually by selecting the frequency that controlled its electron spin.

“The ability to engineer the number of atoms within the qubits provides a way of selectively addressing one qubit from another, resulting in lower error rates even though they are so closely spaced,” says Professor Simmons. “These results highlight the ongoing advantages of atomic qubits in silicon.”

Tuning in and individually controlling qubits within a 2 qubit system is a precursor to demonstrating the entangled states that are necessary for a quantum computer to function and carry out complex calculations.

“We can tune into this or that molecule – a bit like tuning in to different radio stations,” says Sam Hile, lead co-author of the paper and Research Fellow at UNSW. “It creates a built-in address which will provide significant benefits for building a silicon quantum computer.”

Read paper here
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Centre researchers set world record simulating quantum power

CQC2T scientists from the University of Melbourne have set a world record in simulating quantum power on a classical computer, a key step in becoming 'quantum-ready' ahead of when actual quantum computers are scaled up in size. Deputy Director of CQC2T, Professor Lloyd Hollenberg and team members Dr Charles Hill and lead author Masters student Aidan Dang, simulated the output of a 60-qubit quantum computer, which in general would require up to 18,000 petabytes, or more than a billion laptops, to describe – capabilities well beyond the largest supercomputer.

A representation of quantum computing in action showing the “forest” of differing probabilities that the machine uses to more efficiently guide it towards the answer to a problem. The above example is a simulation of a quantum computer finding the prime factors of a number using Shor’s Algorithm.
Picture: Matthew Davis, Gregory White and Aidan Dang

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CQC2T Deputy Director Lloyd Hollenberg elected a Fellow of the Australian Academy

CQC2T Deputy Director Professor Lloyd Hollenberg

Professor Lloyd Hollenberg, who is Deputy Director of CQC2T, the Thomas Baker Chair at the University of Melbourne, and an Australian Research Council Laureate Fellow, has been elected today as a Fellow of the Australian Academy of Science.

Lloyd has created the physical-quantum information basis for a full-scale silicon quantum computer, drawing on his deep understanding of the physics involved. He has achieved major theoretical and experimental advances in the use of nitrogen-vacancy centres in diamond as quantum sensors in physical and biological applications. The Director, Chief Investigators, research staff and students congratulate Lloyd on his achievements.

More information here

CQC2T Director Professor Michelle Simmons elected Fellow of the Royal Society

CQC2T Director Professor Michelle Simmons

The Royal Society of London, the world’s oldest independent scientific academy, announced Professor Michelle Simmons has been elected to receive a Fellowship of the Royal Society.

The fellowship, which is the highest scientific honour bestowed by the academy, is a lifetime membership. Fellowships are awarded to individuals who have been judged to have made a “substantial contribution to the improvement of natural knowledge, including mathematics, engineering science and medical science.”

More information here

CQC2T researchers (Griffith Uni) report Big Bell Test work in Nature

CQC2T researchers at Griffith University have played an important role in a major international collaboration that tested quantum nonlocality – Einsten’s “spooky action at a distance” – in a suite of experiments worldwide. Nonlocal effects such as entanglement underlie the quantum computation and communication technologies being pursued in CQC2T. The joint work of the “Big Bell Test” (BBT) consortium, published in Nature today (https://www.nature.com/articles/s41586-018-0085-3) , used random numbers sourced from people’s free will to rigorously ensure unpredictability in the measurement settings required for such tests. The project used an online game through which members of the public provided random numbers to the experiments in real time. Thus, the project is a flagship for new approaches to citizen involvement in science, and for science outreach.

The Griffith University team, led by Dr Raj Patel and Professor Geoff Pryde, performed a test of "quantum steering” as part of the BBT. Steering is a practical form of quantum non-locality testing that is resistant to real-world device imperfections, and has direct application to quantum communication tasks such as verifying that entanglement has been shared between remote parties. Pryde said, “One of the things that was exciting and really interesting for us was to be part of a big project that required a large amount of coordination. From compiling random numbers from the public to disseminating them between the experiments, and receiving and using them in a timely way, the level of collaboration was remarkable. I also particularly enjoyed the outreach and public involvement side; I enjoyed that we gave people an opportunity to do something which influenced how the experiment ran.”


CQC2T CI Prof Michael Bremner (UTS) co-authors Nature Physics paper on quantum supremacy

CQC2T CI Prof Michael Bremner (UTS)

CQC2T CI Prof Michael Bremner (UTS) links with Google, NASA, UCSB on Nature Physics paper to try to define when quantum computers will overtake classical computers. The researchers said that quantum computers would need almost 50 qubits to process information exponentially faster than a classical supercomputer.

UTS said the first research marks the first clear attempt to identify a benchmark at which quantum computing will surpass the capability of classical computers - which is known as quantum supremacy.
Chief investigator of the UTS branch of the ARC Centre for Quantum Computation and Communication Technology, Professor Michael Bremner, said the line was difficult to define because the advantages offered by quantum computers can be subtle.

“Some applications can have an exponential quantum speed-up over classical computers, while others receive no benefit at all,” he said.
“Understanding when quantum computers become useful is essential, especially when we are limited to using the noisy intermediate-scale devices that currently exist.

“We attempted to find the frontier between classical and quantum computing. We wanted to find the smallest quantum circuits that can do something that cannot be done at all on a classical computer.”