Nav: Home

Precise quantum cloning: Possible pathway to secure communication

October 26, 2016

Physicists at The Australian National University (ANU) and University of Queensland (UQ) have produced near-perfect clones of quantum information using a new method to surpass previous cloning limits.

A global race is on to use quantum physics for ultra-secure encryption over long distances according to Prof Ping Koy Lam, node director of the ARC Centre of Excellence for Quantum Computation and Communication Technology (CQC2T) at ANU.

The new cloning method uses high performance optical amplifiers to clone light encoded with quantum information -- it is possible this technique could allow quantum encryption to be implemented with existing fibre optic infrastructure.

"One obstacle to sending quantum information is that the quantum state degrades before reaching its destination. Our cloner has many possible applications, and could help overcome this problem to achieve secure long distance communication," said Prof Lam.

The laws of physics -- in particular the 'No Cloning Theorem' -- prevent high quality clones being produced with a 100 percent success rate. The team, led by Prof Lam, uses a probabilistic method to demonstrate that it's possible to produce clones that exceed theoretical quality limits. The method was initially proposed by CQC2T researchers led by Prof Timothy Ralph at UQ.

"Imagine Olympic archers being able to choose the shots that land closest to the target's centre to increase their average score," said Prof Ralph.

"By designing our experiment to have probabilistic outputs, we sometimes 'get lucky' and recover more information than is possible using existing deterministic cloning methods. We use the results closest to a 'bullseye' and discard the rest," he said.

A distinct difference between archery and quantum information information is that the probabilistic method is permitted, and is useful in many crypto-communication situations, such as generating secret keys.

"Our probabilistic cloning method generates higher quality quantum clones than have ever been made before, with a success rate of about 5 percent. We can now create up to five clones of a single quantum state," said lead author Jing Yan Haw, ANU PhD researcher.

"We first encode information onto a light beam. Because this information is in a fragile quantum state, it is difficult to observe or measure," said Haw.

"At the heart of the demonstration is a 'noiseless optical amplifier'. When the amplification is good enough, we can then split a light beam into clones. 'Amplify-then-split' allows us to clone the light beam with minimal distortion, so that it can still be read with exquisite precision," said Prof Ralph.

Quantum cloning opens up important experimental possibilities as well as having applications in ultra-secure long distance quantum networks.

"One of the problems with quantum encryption is its limited communication range. We hope this technology could be used to extend the range of communication, and one day lead to impenetrable privacy between two communicating parties," said Prof Lam.

This latest achievement follows the success of fellow CQC2T researchers at ANU, who last month were the first to demonstrate self-stabilising stationary light.

The quantum cloning results are published in Nature Communications.

Watch a video interview with the researchers about their light cloning technique.
-end-


Centre for Quantum Computation & Communication Technology

Related Quantum Information Articles:

The multi-colored photons that might change quantum information science
With leading corporations now investing in highly expensive and complex infrastructures to unleash the power of quantum technologies, INRS researchers have achieved a breakthrough in a light-weight photonic system created using on-chip devices and off-the-shelf telecommunications components.
Celebrating a high performing new journal in quantum information
UNSW Sydney is proud of the early publication performance, influence and reach of its Nature Partner Journal npj Quantum Information, from advancing discovery to affecting public discourse.
Quantum nanoscope
Researchers have studied how light can be used to 'see' the quantum nature of an electronic material.
Testing quantum field theory in a quantum simulator
Quantum field theories are often hard to verify in experiments.
Looking for the quantum frontier
Researchers have developed a new theoretical framework to identify computations that occupy the 'quantum frontier' -- the boundary at which problems become impossible for today's computers and can only be solved by a quantum computer.
Information avoidance
People deliberately avoid information that threatens their happiness and wellbeing.
More reliable way to produce single photons for quantum information imprinting
Physicists at the University of Bath have developed a technique to more reliably produce single photons that can be imprinted with quantum information.
New quantum states for better quantum memories
How can quantum information be stored as long as possible?
Tracking the flow of quantum information
A Yale-led group of researchers has derived a formula for understanding where quantum objects land when they are transmitted.
Breakthrough in the quantum transfer of information between matter and light
From stationary to flying qubits at speeds never reached before...This feat, achieved by a team from Polytechnique Montréal and France's Centre national de la recherche scientifique, brings us a little closer to the era when information is transmitted via quantum principles.

Related Quantum Information Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Changing The World
What does it take to change the world for the better? This hour, TED speakers explore ideas on activism—what motivates it, why it matters, and how each of us can make a difference. Guests include civil rights activist Ruby Sales, labor leader and civil rights activist Dolores Huerta, author Jeremy Heimans, "craftivist" Sarah Corbett, and designer and futurist Angela Oguntala.
Now Playing: Science for the People

#521 The Curious Life of Krill
Krill may be one of the most abundant forms of life on our planet... but it turns out we don't know that much about them. For a create that underpins a massive ocean ecosystem and lives in our oceans in massive numbers, they're surprisingly difficult to study. We sit down and shine some light on these underappreciated crustaceans with Stephen Nicol, Adjunct Professor at the University of Tasmania, Scientific Advisor to the Association of Responsible Krill Harvesting Companies, and author of the book "The Curious Life of Krill: A Conservation Story from the Bottom of the World".