Ultrabright lasers help switch single photons

March 31, 2014 by Joanna Wheatley
Cartoon of the four-way multiplexed light source showing on-chip photon generation and routing. Credit: Bernard Gay-Para.

(Phys.org) —In the search for a single photon source, researchers in Australia and France have achieved a major step towards a turn-key source of individual, precisely tailored photons from an integrated optical chip.

A high quality source of single is vital for advances in including simulation of , truly secure communication and ultimately quantum computation.

But as Macquarie PhD student and lead author Thomas Meany explains, "Unfortunately, nature is reluctant to create photons one at a time—they tend to come out in bunches. This is a serious impediment we have to overcome in order to make a useful tool."

The work, reported in Laser & Photonics Reviews, involved collaboration between researchers from the ARC Centre of Excellence for Ultrahigh bandwidth Devices for Optical Systems (CUDOS) at Macquarie University and The University of Sydney, and a team from the Laboratoire de Physique de la Matière Condensée at the Université Nice Sophia Antipolis in Nice, France.

Since no single optical device can perform all the required operations, the international team tackled the problem using an approach of hybrid integration - combining different optical materials and components into one device in order to exploit the best of each technology.

They combined passive glass routers created by femtosecond laser writing, nonlinear waveguides in a highly advanced , and fast optical switching elements. The photons were generated in a lithium niobate chip developed in the group of Professor Sébastien Tanzilli and Dr Olivier Alibart at the Université Nice Sophia Antipolis. Femtosecond laser-written glass circuits produced at Macquarie were used to embed the Nice chip into the larger experiment.

"Our chip allows the generation of up to four photons simultaneously, but as they appear randomly, we can't predict where or when the next photon will appear," said Dr Alibart. "Further, lithium niobate is a wonderful nonlinear optical material, but it doesn't interface easily with other components. The strategy of this collaboration was to use Macquarie's laser-written waveguides both to deliver pump light to our chip and to guide the outgoing single photons towards the switching array that selects the correct output channel."

In 2013, a landmark CUDOS experiment at the University of Sydney showed how to combine photons from two sources on a silicon chip, using ultrafast optical switches to break the intrinsic noise limit of photon sources. This new result shows that this approach is scalable – what works for a couple of sources can, excitingly, be extended to work with many – and can be applied to other types of waveguide, with more versatility in connecting different platforms.

"The laser-writing technology underlying this advance has numerous applications including quantum processing, as in this work, lasers for biology, and even the search for extra-solar planets" said Macquarie CUDOS Node director, Professor Michael Withford, who has been developing the writing technology for a decade.

"Our systems can build of almost arbitrary 3D form in simple glass chips. We continually find that because of this flexibility and ease of fabrication, femtosecond-written waveguides are perfect for connecting different to create a single functional device."

Explore further: Memory closes in on single photons

More information: Hybrid photonic circuit for multiplexed heralded single photons. Thomas Meany, Lutfi A. Ngah, Matthew J. Collins, Alex S. Clark, Robert J. Williams, Benjamin J. Eggleton, M. J. Steel, Michael J. Withford, Olivier Alibart, Sébastien Tanzilli. On Arxiv: arXiv:1402.7202 [quant-ph] arxiv.org/abs/1402.7202

Related Stories

Memory closes in on single photons

March 18, 2014

(Phys.org) —In a world-first, an optical memory – a key component for quantum computers – has been created within a hollow-core optical fibre and shown to operate at the level of a single particle of light (a photon).

Unavoidable disorder used to build nanolaser

March 23, 2014

Researchers the world round are working to develop optical chips, where light can be controlled with nanostructures. These could be used for future circuits based on light (photons) instead of electron - that is photonics ...

Integration brings quantum computer a step closer

January 30, 2014

An international research group led by the University of Bristol has made an important advance towards a quantum computer by shrinking down key components and integrating them onto a silicon microchip.

Recommended for you

Two teams independently test Tomonaga–Luttinger theory

October 20, 2017

(Phys.org)—Two teams of researchers working independently of one another have found ways to test aspects of the Tomonaga–Luttinger theory that describes interacting quantum particles in 1-D ensembles in a Tomonaga–Luttinger ...

Using optical chaos to control the momentum of light

October 19, 2017

Integrated photonic circuits, which rely on light rather than electrons to move information, promise to revolutionize communications, sensing and data processing. But controlling and moving light poses serious challenges. ...

Black butterfly wings offer a model for better solar cells

October 19, 2017

(Phys.org)—A team of researchers with California Institute of Technology and the Karlsruh Institute of Technology has improved the efficiency of thin film solar cells by mimicking the architecture of rose butterfly wings. ...

Terahertz spectroscopy goes nano

October 19, 2017

Brown University researchers have demonstrated a way to bring a powerful form of spectroscopy—a technique used to study a wide variety of materials—into the nano-world.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.