Tiny camera lens may help link quantum computers to network


Tiny Camerra Lens 180913142057_1_540x360
Kai Wang holding a sample that has multiple metasurface camera lenses.
Credit: Lannon Harley, ANU

An international team of researchers led by The Australian National University (ANU) has invented a tiny camera lens, which may lead to a device that links quantum computers to an optical fibre network.

Quantum computers promise a new era in ultra-secure networks, artificial intelligence and therapeutic drugs, and will be able to solve certain problems much faster than today’s computers.

The unconventional lens, which is 100 times thinner than a human hair, could enable a fast and reliable transfer of quantum information from the new-age computers to a network, once these technologies are fully realised.

The device is made of a silicon film with millions of nano-structures forming a metasurface, which can control light with functionalities outperforming traditional systems.

Associate Professor Andrey Sukhorukov said the metasurface camera lens was highly transparent, thereby enabling efficient transmission and detection of information encoded in quantum light.

“It is the first of its kind to image several quantum particles of light at once, enabling the observation of their spooky behaviour with ultra-sensitive cameras,” said Associate Professor Sukhorukov, who led the research with a team of scientists at the Nonlinear Physics Centre of the ANU Research School of Physics and Engineering.

Kai Wang, a PhD scholar at the Nonlinear Physics Centre who worked on all aspects of the project, said one challenge was making portable quantum technologies.

“Our device offers a compact, integrated and stable solution for manipulating quantum light. It is fabricated with a similar kind of manufacturing technique used by Intel and NVIDIA for computer chips.” he said.

The research was conducted at the Nonlinear Physics Centre laboratories, where staff and postgraduate scholars developed and trialled the metasurface camera lens in collaboration with researchers at the Oak Ridge National Laboratory in the United States and the National Central University in Taiwan.

Story Source:

Materials provided by Australian National UniversityNote: Content may be edited for style and length.


Journal Reference:

  1. Kai Wang, James G. Titchener, Sergey S. Kruk, Lei Xu, Hung-Pin Chung, Matthew Parry, Ivan I. Kravchenko, Yen-Hung Chen, Alexander S. Solntsev, Yuri S. Kivshar, Dragomir N. Neshev, Andrey A. Sukhorukov. Quantum metasurface for multiphoton interference and state reconstructionScience, 2018; 361 (6407): 1104-1108 DOI: http://dx.doi.org/10.1126/science.aat8196
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Australian National University Claim: Hydro storage can secure 100 percent renewable electricity -What Do You Think?


hydrostoragePumped hydro storage can be used to help build a secure and cheap Australian electricity grid with 100 per cent renewable energy, a new study from The Australian National University (ANU) has found.

 

Lead researcher Professor Andrew Blakers from ANU said the zero-emissions grid would mainly rely on wind and solar photovoltaic (PV) technology, with support from pumped hydro storage, and would eliminate Australia’s need for coal and gas-fired power.

“With Australia wrestling with how to secure its energy supply, we’ve found we can make the switch to affordable and reliable clean power,” said Professor Blakers from the ANU Research School of Engineering.

Professor Blakers said wind and solar PV provided nearly all new generation capacity in Australia and half the world’s new generation capacity each year. At present, renewable energy accounts for around 15 per cent of Australia’s electricity generation while two thirds comes from coal-fired power stations.

“However, most existing coal and gas stations will retire over the next 15 years, and it will be cheaper to replace them with wind and solar PV,” he said.

The ANU research considers the potential benefits of using hydro power , where water is pumped uphill and stored to generate electricity on demand.

“Pumped hydro energy storage is 97 per cent of all storage worldwide, and can be used to support high levels of solar PV and wind,” Professor Blakers said.

Hydro storage can secure 100% renewable electricity
Map showing South Australia’s extensive array of potential pumped hydro energy storage sites (excluding national parks and other protected areas). In general, larger heads (red areas) lead to lower cost. Credit: Australian National University

Professor Blakers said the cost of a 100 per cent stabilized renewable electricity system would be around AU$75/MWh, which is cheaper than coal and gas-fueled power.

ANU is leading a study to map potential short-term off-river pumped hydro energy storage (STORES) sites that could support a much greater share of in the grid.

STORES sites are pairs of reservoirs, typically 10 hectares each, which are separated by an altitude difference of between 300 and 900 metres, in hilly terrain, and joined by a pipe with a pump and turbine. Water is circulated between the upper and lower reservoirs in a closed loop to store and generate power.

Dr Matthew Stocks from the ANU Research School of Engineering said STORES needed much less water than power generated by fossil fuels and had minimal impact on the environment because water was recycled between the small reservoirs.

“This hydro power doesn’t need a river and can go from zero to full in minutes, providing an effective method to stabilise the grid,” he said.

“The water is pumped up from the low reservoir to the high reservoir when the sun shines and wind blows and electricity is abundant, and then the can run down through the turbine at night and when electricity is expensive.”

Co-researcher Mr Bin Lu said Australia had hundreds of potential sites for STORES in the extensive hills and mountains close to population centres from North Queensland down the east coast to South Australia and Tasmania.

Explore further: How South Australia can function reliably while moving to 100% renewable power

More information: 100% renewable electricity in Australia: energy.anu.edu.au/files/100%25%20renewable%20electricity%20in%20Australia.pdf

 

New material to revolutionize water proofing


 

 

AUSTRALIAN NATIONAL UNIVERSITY

Scientists at The Australian National University (ANU) have developed a new spray-on material with a remarkable ability to repel water.

The new protective coating could eventually be used to waterproof mobile phones, prevent ice from forming on aeroplanes or protect boat hulls from corroding.

“The surface is a layer of nanoparticles, which water slides off as if it’s on a hot barbecue,” said PhD student William Wong, from the Nanotechnology Research Laboratory at the ANU Research School of Engineering.

The team created a much more robust coating than previous materials by combining two plastics, one tough and one flexible.

“It’s like two interwoven fishing nets, made of different materials,” Mr Wong said.

The water-repellent or superhydrophobic coating is also transparent and extremely resistant to ultraviolet radiation.

Lead researcher and head of the Nanotechnology Research Laboratory, Associate Professor Antonio Tricoli, said the new material could change how we interact with liquids.

“It will keep skyscraper windows clean and prevent the mirror in the bathroom from fogging up,” Associate Professor Tricoli said.

“The key innovation is that this transparent coating is able to stabilise very fragile nanomaterials resulting in ultra-durable nanotextures with numerous real-world applications.”

The team developed two ways of creating the material, both of which are cheaper and easier than current manufacturing processes.

One method uses a flame to generate the nanoparticle constituents of the material. For lower temperature applications, the team dissolved the two components in a sprayable form.

In addition to waterproofing, the new ability to control the properties of materials could be applied to a wide range of other coatings, said Mr Wong.

“A lot of the functional coatings today are very weak, but we will be able to apply the same principles to make robust coatings that are, for example, anti-corrosive, self-cleaning or oil-repellent,” he said.

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The research is published in ACS Appl. Mater. Interfaces 2016, 8, 13615?13623.

Images and videos, including a slow motion demonstration, are available at https://www.dropbox.com/sh/s9fe42t74zoxv54/AAD2ZYRCjMK-0gOGvZ7F8nNca?dl=0.

NEW Nanomaterial Holds Promise for Highly Efficient Thermo-Photovoltaic Solar Cells – Solar Energy at Night?


Thermo 041816 nanomaterialDr Kruk next to a diagram of the metamaterial structure. Credit: Stuart Hay, ANU

Overview: “Thermophotovoltaic cells have the potential to be much more efficient than solar cells,” said Dr Sergey Kruk from the ANU Research School of Physics and Engineering.

” … a nanomaterial which opens new possibilities for highly efficient thermophotovoltaic cells, which could one day harvest heat in the dark and turn it into electricity.” – Dr. Kruk

Physicists have discovered radical new properties in a nanomaterial which opens new possibilities for highly efficient thermophotovoltaic cells, which could one day harvest heat in the dark and turn it into electricity.

The research team from the Australian National University (ARC Centre of Excellence CUDOS) and the University of California Berkeley demonstrated a new artificial material, or metamaterial, that glows in an unusual way when heated.

The findings could drive a revolution in the development of which convert radiated heat into electricity, known as thermophotovoltaic cells.

“Thermophotovoltaic cells have the potential to be much more efficient than solar cells,” said Dr Sergey Kruk from the ANU Research School of Physics and Engineering.

“Our metamaterial overcomes several obstacles and could help to unlock the potential of thermophotovoltaic cells.”

Thermophotovoltaic cells have been predicted to be more than two times more efficient than conventional . They do not need direct sunlight to generate electricity, and instead can harvest heat from their surroundings in the form of infrared radiation.

They can also be combined with a burner to produce on-demand power or can recycle heat radiated by hot engines.

The research is published in Nature Communications.

The team’s metamaterial, made of tiny nanoscopic structures of gold and magnesium fluoride, radiates heat in specific directions. The geometry of the metamaterial can also be tweaked to give off radiation in specific spectral range, in contrast to standard materials that emit their heat in all directions as a broad range of infrared wavelengths. This makes it ideal for use as an emitter paired with a thermophotovoltaic cell.

The project started when Dr Kruk predicted the new metamaterial would have these surprising properties. The ANU team then worked with scientists at the University of California Berkeley, who have unique expertise in manufacturing such materials.

“To fabricate this material the Berkeley team were operating at the cutting edge of technological possibilities,” Dr Kruk said.

“The size of individual building block of the metamaterial is so small that we could fit more than twelve thousand of them on the cross-section of a human hair.”

The key to the metamaterial’s remarkable behaviour is its novel physical property, magnetic hyperbolic dispersion. Dispersion describes the interactions of light with materials and can be visualized as a three-dimensional surface representing how electromagnetic radiation propagates in different directions. For natural materials, such as glass or crystals the dispersion surfaces have simple forms, spherical or ellipsoidal.

The dispersion of the new metamaterial is drastically different and takes hyperbolic form. This arises from the material’s remarkably strong interactions with the magnetic component of light.

The efficiency of thermovoltaic cells based on the metamaterial can be further improved if the emitter and the receiver have just a nanoscopic gap between them. In this configuration, radiative transfer between them can be more than ten times more efficient than between conventional materials.

Explore further: ‘Darker-than-black’ metamaterial could lead to more efficient solar cells

More information: Sergey S. Kruk et al. Magnetic hyperbolic optical metamaterials, Nature Communications (2016). DOI: 10.1038/ncomms11329

 

ITMO & Australia National University: Invisible Hobbits & Harry Potter? Creating Invisible Objects Without Metamaterial Cloaking


Invisible Meta Cloaking 041415 id39742Physicists from ITMO University, Ioffe Institute and Australian National University managed to make homogenous cylindrical objects completely invisible in the microwave range. Contrary to the now prevailing notion of invisibility that relies on metamaterial coatings, the scientists achieved the result using a homogenous object without any additional coating layers. The method is based on a new understanding of electromagnetic wave scattering. The results of the study were published in Scientific Reports (“Switching from Visibility to Invisibility via Fano Resonances: Theory and Experiment”).
Radio Anechoic Chamber at Metamaterials Laboratory
This is the radio-frequency anechoic chamber used for the experiment. (Research: ITMO University)
The scientists studied light scattering from a glass cylinder filled with water. In essence, such an experiment represents a two-dimensional analog of a classical problem of scattering from a homogeneous sphere (Mie scattering), the solution to which is known for almost a century. However, this classical problem contains unusual physics that manifests itself when materials with high values of refractive index are involved. In the study, the scientists used ordinary water whose refractive index can be regulated by changing temperature.
As it turned out, high refractive index is associated with two scattering mechanisms: resonant scattering, which is related to the localization of light inside the cylinder, and non-resonant, which is characterized by smooth dependence on the wave frequency. The interaction between these mechanisms is referred to as Fano resonances. The researchers discovered that at certain frequencies waves scattered via resonant and non-resonant mechanisms have opposite phases and are mutually destroyed, thus making the object invisible.
The work led to the first experimental observation of an invisible homogeneous object by means of scattering cancellation. Importantly, the developed technique made it possible to switch from visibility to invisibility regimes at the same frequency of 1.9 GHz by simply changing the temperature of the water in the cylinder from 90 °C to 50 °C.
“Our theoretical calculations were successfully tested in microwave experiments. What matters is that the invisibility idea we implemented in our work can be applied to other electromagnetic wave ranges, including to the visible range. Materials with corresponding refractive index are either long known or can be developed at will,” said Mikhail Rybin, first author of the paper and senior researcher at the Metamaterials Laboratory in ITMO University.
The discovery of invisibility phenomenon in a homogenous object and not an object covered with additional coating layers is also important from the engineering point of view. Because it is much easier to produce a homogeneous cylinder, the discovery could prompt further development of nanoantennas, wherein invisible structural elements could help reduce disturbances. For instance, invisible rods could be used as supports for a miniature antenna complex connecting two optical chips.
The subject of invisibility came into prominence with the development of metamaterials – artificially designed structures with optical properties that are not encountered elsewhere in nature. Metamaterials are capable of changing the direction of light in exotic ways, including making light curve around the cloaked object. Nevertheless, coating layers based on metamaterials are extremely hard to fabricate and are not compatible with many other invisibility ideas. The method developed by the group is based on a new understanding of scattering processes and leaves behind the existing ones in simplicity and cost-effectiveness.
Source: ITMO University

Read more: Scientists create invisible objects without metamaterial cloaking

Vaporware: Scientists Use Cloud of Atoms as Optical Memory Device


QDOTS imagesCAKXSY1K 8Talk about storing data in the cloud. Scientists at the Joint Quantum Institute (JQI) of the National Institute of Standards and Technology (NIST) and the University of Maryland have taken this to a whole new level by demonstrating* that they can store visual images within quite an ethereal memory device—a thin vapor of rubidium atoms. The effort may prove helpful in creating memory for quantum computers.

This brief animation (click link to launch mp4) by the NIST/JQI team shows the NIST logo they stored within a vapor of rubidium atoms and three different portions of it that they were able to extract at will. Animation combines three actual images from the vapor extracted at different times.

Their work builds on an approach developed at the Australian National University, where scientists showed that a rubidium vapor could be manipulated in interesting ways using magnetic fields and lasers. The vapor is contained in a small tube and magnetized, and a laser pulse made up of multiple light frequencies is fired through the tube. The energy level of each rubidium atom changes depending on which frequency strikes it, and these changes within the vapor become a sort of fingerprint of the pulse’s characteristics. If the field’s orientation is flipped, a second pulse fired through the vapor takes on the exact characteristics of the first pulse—in essence, a readout of the fingerprint.

“With our paper, we’ve taken this same idea and applied it to storing an image—basically moving up from storing a single ‘pixel’ of light information to about a hundred,” says Paul Lett, a physicist with JQI and NIST’s Quantum Measurement Division. “By modifying their technique, we have been able to store a simple image in the vapor and extract pieces of it at different times.”

It’s a dramatic increase in the amount of information that can be stored and manipulated with this approach. But because atoms in a vapor are always in motion, the image can only be stored for about 10 milliseconds, and in any case the modifications the team made to the original technique introduce too much noise into the laser signal to make the improvements practically useful. So, should the term vaporware be applied here after all? Not quite, says Lett—because the whole point of the effort was not to build a device for market, but to learn more about how to create memory for next-generation quantum computers.

“What we’ve done here is store an image using classical physics. However, the ultimate goal is to store quantum information, which a quantum computer will need,” he says. “Measuring what the rubidium atoms do as we manipulate them is teaching us how we might use them as quantum bits and what problems those bits might present. This way, when someone builds a solid-state system for a finished computer, we’ll know how to handle them more effectively.”

*J.B. Clark, Q. Glorieux and P.D. Lett. Spatially addressable readout and erasure of an image in a gradient echo memory. New Journal of Physics, doi: 10.1088/1367-2630/15/3/035005, 06 March 2013.