“Beam Me Up Scotty” ~ Teleportation of light particles across cities in China and Canada a ‘technological breakthrough’!


teleportation-091916-7853834-3x2-700x467

Scientists have shown they can teleport matter across a city, a development that has been hailed as “a technological breakthrough”.

However, do not expect to see something akin to the Star Trek crew beaming from the planet’s surface to the Starship Enterprise. star-trek-transporter-1280jpg-883390_1280w

Instead, in the two studies, published today in Nature Photonics, separate research groups have used quantum teleportation to send photons to new locations using fibre-optic communications networks in the cities of Hefei in China and Calgary in Canada.

Quantum teleportation is the ability to transfer information such as the properties or the quantum state of an atom — its energy, spin, motion, magnetic field and other physical properties — to another location without travelling in the space between.

Key points

  • Two experiments demonstrate teleportation of particles across real optical fibre networks for first time
  • Chinese experiment transports two photons per hour across seven kilometres
  • Canadian experiment transports 17 photons per minute across 6.2 kilometres

 

While it was first demonstrated in 1997, today’s studies are the first to show the process is technologically possible via a mainstream communications network.

The development could lead to future city-scale quantum technologies and communications networks, such as a quantum internet and improved security of internet-based information.

Dr. Ben Buchler, Associate Professor with the Centre for Quantum Computation and Communication Technology at the Australian National University, said the technical achievement of completing the experiments in a “non-ideal environment” was “pretty profound”.

“People have known how to do this experiment since the early 2000s, but until these papers it hasn’t been performed in fibre communication networks, in situ, in cities,” said Dr. Buchler, who was not involved in the research.

“It’s seriously difficult to do what they have done.”

Watch the YouTube Video: “The Metaphysics of Teleportation” – Dr. Michio Kaku

 

A cornerstone of quantum teleportation is quantum entanglement, where two particles are intimately linked to each other in such a way that a change in one will affect the other.

Dr. Buchler said quantum teleportation involved mixing a photon with one branch of the entanglement and this joint element was then measured. The other branch of the entanglement was sent to the receiving party or new location.

This original ‘joint’ measurement is sent to the receiver, who can then use that information to manipulate the other branch of the entanglement.

“The thing that pops out is the original photon, in a sense it has indistinguishable characteristics from the one you put in,” Dr Buchler said.

Overcoming technical barriers

He said both teams had successfully overcome technical barriers to ensure the precise timing of photon arrival and accurate polarisation within the fibres.

The Chinese team teleported single protons using the standard telecommunications wavelength across a distance of seven kilometres, whiled the Canadian team teleported single photons up to 6.2 kilometres.

But work remained to increase the speed of the system with the Chinese group teleporting just two photons per hour and the Canadians a faster rate of 17 photons per minute.

Dr. Buchler said the speeds meant the development had little immediate practical value, but “this kind of teleportation is part of the protocol people imagine will be able to extend the range of quantum key distribution” — a technique used to send secure encrypted messages.

In the future scientists envision the evolution of a quantum internet that would allow the communication of quantum information between quantum computers.

Quantum computers on their own would allow fast computation, but networked quantum computers would be more powerful still.

Dr. Buchler said today’s studies were a foundation stone toward that vision as it showed it was possible to move quantum information from one location to another within mainstream networks without destroying it.

Yes … a LOT more work has to be done however before we “Warp” and “Beam” … but to put it into the words of ‘The Good Doctor’ …

“Damit Jim, I’m ONLY a doctor!” (Highly Logical) “Live long and Prosper!”

star_trek_bridge_crew_vr_ubisoft_screen_shot

 

 

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MIT: Seeking sustainable solutions through Nanotechnology – Engineer’s designs may help purify water, diagnose disease in remote regions of world.


mit-karnik-rohit-1“I try to guide my research by … asking myself the question, ‘What can we do today that will have a lasting impact and be conducive to a sustainable human civilization?’” says Rohit Karnik, an associate professor in MIT’s Department of Mechanical Engineering. Photo: Ken Richardson

In Rohit Karnik’s lab, researchers are searching for tiny solutions to some of the world’s biggest challenges.

In one of his many projects, Karnik, an associate professor in MIT’s Department of Mechanical Engineering, is developing a new microfluidic technology that can quickly and simply sorts cells from small samples of blood. The surface of a microfluidic channel is patterned to direct certain cells to roll toward a reservoir for further analysis, while allowing the rest of the blood sample to pass through. With this design, Karnik envisions developing portable, disposable devices that doctors may use, even in remote regions of the world, to quickly diagnose conditions ranging from malaria to sepsis.

Karnik’s group is also tackling issues of water purification. The researchers are designing filters from single layers of graphene, which are atom-thin sheets of carbon known for their exceptional strength. Karnik has devised a way to control the size and concentration of pores in graphene, and is tailoring single layers to filter out miniscule and otherwise evasive contaminants. The group has also successfully filtered salts using the technique and hopes to develop efficient graphene filters for water purification and other applications. Silver Nano P clean-drinking-water-india

In looking for water-purifying solutions, Karnik’s group also identified a surprisingly low-tech option: the simple tree branch. Karnik found that the pores within a pine branch that normally help to transport water up the plant are ideal for filtering bacteria from water. The group has shown that a peeled pine branch can filter out up to 99.00 percent of E. coli from contaminated water. Karnik’s group is building up on this work to explore the potential for simple and affordable wood-based water purification systems.

“I try to guide my research by long-term sustainability, in a specific sense, by asking myself the question, ‘What can we do today that will have a lasting impact and be conducive to a sustainable human civilization?’ Karnik says. “I try to align myself with that goal.”

From stargazer to tinkerer

Karnik was born and raised in Pune, India, which was then a relatively quiet city 100 miles east of Mumbai. Karnik describes himself while growing up as shy, yet curious about the way the world worked. He would often set up simple experiments in his backyard, seeing, for instance, how transplanting ants from one colony to another would change the ants’ behavior. (The short answer: They fought, sometimes to the death.) He developed an interest in astronomy early on and often explored the night sky with a small telescope, from the roof of his family’s home.

“I used to take my telescope up to the terrace in the middle of the night, which required three different trips up six or seven flights of stairs,” Karnik says. “I’d set the alarm for 3 a.m., go up, and do quite a bit of stargazing.”

That telescope would soon serve another use, as Karnik eventually found that, by inverting it and adding another lens, he could repurpose the telescope as a microscope.

“I built a little setup so I could look at different things, and I used to collect stuff from around the house, like onion peels or fungus growing on trees, to look at their cells,” Karnik says.

When it came time to decide on a path of study, Karnik was inspired by his uncle, a mechanical engineer who built custom machines “that did all kinds of things, from making concrete bricks, to winding up springs,” Karnik says. “What I saw in mechanical engineering was the ability to building something that integrates across different disciplines.”

Seeking balance and insight

As an entering student at the Indian Institute of Technology Bombay, Karnik chose to study mechanical engineering over electrical engineering, which was the more popular choice among students at the time. For his thesis, he looked for new ways to model three-dimensional cracks in materials such as steel beams.

Casting around for a direction after graduating, Karnik landed on the fast-growing field of nanotechnology. Arun Majumdar, an IIT alum and professor at the University of California at Berkeley, was studying energy conversion and biosensing in nanoscale systems. Karnik joined the professor’s lab as a graduate student, moving to California in 2002. For his graduate work, Karnik helped to develop a microfluidic platform to rapidly mix the contents of and test reactions occurring within droplets. He followed this work up with a PhD thesis in which he explored how fluid, flowing through tiny, nanometer-sized channels, can be controlled  to sense and direct ions and molecules.

Toward the end of his graduate work, Karnik interviewed for and ultimately accepted a faculty position at MIT. However, he was still completing his PhD thesis at Berkeley and had less than 4 years of experience beyond his bachelor’s degree. To help ease the transition, MIT offered Karnik an interim postdoc position in the lab of Robert Langer, the David H. Koch Institute Professor and a member of the Koch Institute for Integrative Cancer Research.

“It was an insightful experience,” Karnik remembers. “For a mechanical engineer who’s never been outside mechanical engineering, I basically had little experience how to do things in biology. It opened up possibilities for working with the biomedical community.”

When Karnik finally assumed his position as assistant professor of mechanical engineering in 2007, he experienced a tidal wave of deadlines, demands, and responsibilities — a common initiation for first-time faculty.

“By its nature the job is overwhelming,” Karnik says. “The trick is how to maintain balance and sanity and do the things you like, without being distracted by the busyness around you, in some sense.”

He says several things have helped him to handle and even do away with stress: walks, which he takes each day to work and around campus, as well as yoga and meditation.

“If you can see things the way they are, by clearing away the filters your mind puts in place, you can get a clear perspective, and there are a lot of insights that come through,” Karnik says.

Argonne National Laboratory-led projects among $39.8 million in first-round “Exascale” Computing Project awards -Enabled Precision Medicine for Cancer


doe-iii-doeThe U.S. Department of Energy’s (DOE’s) Exascale Computing Project (ECP) today announced its first round of funding with the selection of 15 application development proposals for full funding and seven proposals for seed funding, representing teams from 45 research and academic organizations.

Exascale refers to high-performance computing systems capable of at least a billion billion calculations per second, or a factor of 50 to 100 times faster than the nation’s most powerful supercomputers in use today.

The 15 awards being announced total $39.8 million, targeting advanced modeling and simulation solutions to specific challenges supporting key DOE missions in science, clean energy and national security, as well as collaborations such as the Precision Medicine Initiative with the National Institutes of Health’s National Cancer Institute.

Of the proposals announced that are receiving full funding, two are being led by principal investigators at the DOE’s Argonne National Laboratory:

  1. Computing the Sky at Extreme Scales equips cosmologists with the ability to design foundational simulations to create “virtual universes” on demand at the extreme fidelities demanded by future multi-wavelength sky surveys. The new discoveries that will emerge from the combination of sky surveys and advanced simulation provided by the ECP will shed more light on three key ingredients of our universe: dark energy, dark matter and inflation. All three of these concepts reach beyond the known boundaries of the Standard Model of particle physics.Salman Habib, Principal Investigator, Argonne National Laboratory, with Los Alamos National Laboratory and Lawrence Berkeley National Laboratory.argone-ii-nl-mira_-_blue_gene_q_at_argonne_national_laboratory
  1. Exascale Deep Learning and Simulation Enabled Precision Medicine for Cancer focuses on building a scalable deep neural network code called the CANcer Distributed Learning Environment (CANDLE) that addresses three top challenges of the National Cancer Institute: understanding the molecular basis of key protein interactions, developing predictive models for drug response and automating the analysis and extraction of information from millions of cancer patient records to determine optimal cancer treatment strategies.Rick Stevens, Principal Investigator, Argonne National Laboratory, with Los Alamos National Laboratory, Lawrence Livermore National Laboratory, Oak Ridge National Laboratory and the National Cancer Institute.

Additionally, a third project led by Argonne will be receiving seed funding:

  1. Multiscale Coupled Urban Systems will create an integrated modeling framework comprising data curation, analytics, modeling and simulation components that will equip city designers, planners and managers to scientifically develop and evaluate solutions to issues that affect cities now and in the future. The framework will focus first on integrating urban atmosphere and infrastructure heat exchange and air flow; building energy demand at district or city-scale, generation and use; urban dynamics and socioeconomic models; population mobility and transportation; and hooks to expand to include energy systems (biofuels, electricity and natural gas) and water resources.Charlie Catlett, Principal Investigator, Argonne National Laboratory, with Lawrence Berkeley National Laboratory, National Renewable Energy Laboratory, Oak Ridge National Laboratory and Pacific Northwest National Laboratory.

The application efforts will help guide DOE’s development of a U.S. exascale ecosystem as part of President Obama’s National Strategic Computing Initiative. DOE, the U.S. Department of Defense and the National Science Foundation have been designated as lead agencies, and ECP is the primary DOE contribution to the initiative.

The ECP’s multiyear mission is to maximize the benefits of high-performance computing for U.S. economic competitiveness, national security and scientific discovery. In addition to applications, the DOE project addresses hardware, software, platforms and workforce development needs critical to the effective development and deployment of future exascale systems.

argone-nl-090115-114727Leadership of the ECP comes from six DOE national laboratories: the Office of Science’s Oak Ridge, Argonne and Lawrence Berkeley national labs and the National Nuclear Security Administration’s (NNSA’s) Lawrence Livermore, Los Alamos and Sandia national labs.

The Exascale Computing Project is a collaborative effort of two DOE organizations — the Office of Science and the NNSA. As part of President Obama’s National Strategic Computing initiative, ECP was established to develop a capable exascale ecosystem, encompassing applications, system software, hardware technologies and architectures, and workforce development to meet the scientific and national security mission needs of DOE in the mid-2020s timeframe.

Established by Congress in 2000, NNSA is a semi-autonomous agency within DOE responsible for enhancing national security through the military application of nuclear science. NNSA maintains and enhances the safety, security, and effectiveness of the U.S. nuclear weapons stockpile without nuclear explosive testing; works to reduce the global danger from weapons of mass destruction; provides the U.S. Navy with safe and effective nuclear propulsion; and responds to nuclear and radiological emergencies in the United States and abroad.

Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.

The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit the Office of Science website.

U of California: Nano submarines could change healthcare, says nanoengineer professor


Nano Subs 082316 1471860105809A leading global chemist has come to the Sunshine Coast to discuss how his team is close to creating a successful nano submarine that could revolutionise the healthcare system.

When asked what exactly a “nano submarine” was, University of California San Diego chair of nanoengineering professor Joseph Wang described it as like something taken from the 1966 film Fantastic Voyage, where medical personnel board a submarine were shrunk to microscopic size to travel through the bloodstream of a wounded diplomat and save his life.

Professor Wang said his team was getting closer to the goal of using nano submarines in a variety of ways, minus the shrunken humans and sabotage of the 1966 film.

“It’s like the Fantastic Voyage movie, where you want to improve therapeutic and diagnostic abilities through proper timing and proper location to improve efficiency,” he said.

“It is like shrinking a big submarine a million times to get the nano-scale submarine.

“We use special nano fabrications to create it.

“You can call it submarine or a nano machine, there are different names for it.”

One nanometer is one-billionth of a meter. To put this into perspective, a strand of human DNA is 2.5 nanometers in diameter while a sheet of paper is about 100,000 nanometers thick.Nano Subs 061416 untitled

Professor Wang said the nano submarines could be tailored to specific applications, including diagnosis, treatment and imaging and would use energy within the body’s system to generate its movement.

“It is powered by the blood, by chemical in the blood like glucose, it can autonomously move in blood,” he said.

“This is all part of what we call nano medicine, precision medicine that we use to improve medicines.

“It could improve imaging, diagnosis, treatment, it is multifunctional.”

Professor Wang said there was a fair way to go before human testing could begin, but said the pioneering work could improve drug treatments by providing a more targeted approach.

“Compared to (current) drug delivery, it could take cargo, the drug, and dispose it at the right location, right time and could improve the efficiency of drug,” he said.

Professor Wang was presenting a free public seminar on nano submarines at University of Sunshine Coast’s Innovation Centre at Sippy Downs.

 

Nanoparticles that Speed Blood Clotting ~ Great Things from Small Things ~ May One Day Save Lives


Blood Clot NPs 082216 10-nanoparticle.jpgNanoparticles (green) help form clots in an injured liver. The researchers added color to the scanning electron microscopy image after it was taken. Credit: Erin Lavik, Ph.D.

Whether severe trauma occurs on the battlefield or the highway, saving lives often comes down to stopping the bleeding as quickly as possible. Many methods for controlling external bleeding exist, but at this point, only surgery can halt blood loss inside the body from injury to internal organs.

Now, researchers have developed nanoparticles that congregate wherever injury occurs in the body to help it form blood clots, and they’ve validated these particles in test tubes and in vivo.

The researchers will present their work today at the 252nd National Meeting & Exposition of the American Chemical Society (ACS).

“When you have uncontrolled internal bleeding, that’s when these particles could really make a difference,” says Erin B. Lavik, Sc.D. “Compared to injuries that aren’t treated with the nanoparticles, we can cut bleeding time in half and reduce total .”

Trauma remains a top killer of children and younger adults, and doctors have few options for treating internal bleeding. To address this great need, Lavik’s team developed a nanoparticle that acts as a bridge, binding to activated platelets and helping them join together to form clots. To do this, the nanoparticle is decorated with a molecule that sticks to a glycoprotein found only on the activated platelets.

Nano Body II 43a262816377a448922f9811e069be13Initial studies suggested that the nanoparticles, delivered intravenously, helped keep rodents from bleeding out due to brain and spinal , Lavik says. But, she acknowledges, there was still one key question: “If you are a rodent, we can save your life, but will it be safe for humans?”

As a step toward assessing whether their approach would be safe in humans, they tested the immune response toward the particles in pig’s blood. If a treatment triggers an immune response, it would indicate that the body is mounting a defense against the nanoparticle and that side effects are likely. The team added their nanoparticles to pig’s blood and watched for an uptick in complement, a key indicator of immune activation. The particles triggered complement in this experiment, so the researchers set out to engineer around the problem.

“We made a battery of particles with different charges and tested to see which ones didn’t have this immune-response effect,” Lavik explains. “The best ones had a neutral charge.” But neutral nanoparticles had their own problems. Without repulsive charge-charge interactions, the nanoparticles have a propensity to aggregate even before being injected. To fix this issue, the researchers tweaked their nanoparticle storage solution, adding a slippery polymer to keep the nanoparticles from sticking to each other.

Lavik also developed nanoparticles that are stable at higher temperatures, up to 50 degrees Celsius (122 degrees Fahrenheit). This would allow the particles to be stored in a hot ambulance or on a sweltering .

In future studies, the will test whether the new particles activate complement in human blood. Lavik also plans to identify additional critical safety studies they can perform to move the research forward. For example, the team needs to be sure that the do not cause non-specific clotting, which could lead to a stroke. Lavik is hopeful though that they could develop a useful clinical product in the next five to 10 years.

Explore further: Researchers take the inside route to halt bleeding

More information: Engineering nanoparticles to stop internal bleeding, 252nd National Meeting & Exposition of the American Chemical Society (ACS), 2016.

Abstract
Young people between 5 and 44 are most likely to die from a trauma, and the primary cause of death will be bleeding out. We have a range of technologies to control external bleeding, but there is a dearth of technologies for internal bleeding.
Following injury, platelets become activated at the injury site.

We have designed nanoparticles that are administered intravenously that bind with activated platelets to help form platelet plugs more rapidly. We have investigated the behavior of these particles in an number of in vitro systems to understand their behavior. We have also tested these particles in a number of models of trauma. The particles lead to a reduction in bleeding in a number of models of trauma including models of brain and spinal cord injury, and these particles lead to increased survival.
This work is not without challenges. One of the goals is to be able to use these particles in places where there are extreme temperatures and storage is challenging. We have engineering a variant of the hemostatic nanoparticles that is stable up to 50 C. A second challenge is that the intravenous administration of nanoparticles triggers complement activation as has been seen in a wide range of nanoparticle technologies from DOXIL to imaging agents.

The solution is generally to administer the particles very slowly to modulate the physiological responses to complement activation, but that is not an option when one is bleeding out, so we have had to develop variants that reduce complement activation and the accompanying complications.
Ultimately, we hope that this work provides insight and, potentially, a new approach to dealing with internal bleeding.

 

‘Artificial atom’ Created in Graphene ~ What will this Mean? For Quantum Computers? For Quantum Dots?


Artificial Atom QDs 082216 artificialatThe charged tip of a scanning tunneling microscope and an additional magnetic field lead to localized stable electron states in graphene. Credit: Nils Freitag, RWTH Aachen

“Artificial atoms open up new, exciting possibilities, because we can directly tune their properties”, says Professor Joachim Burgdörfer (TU Wien, Vienna).In semiconductor materials such as gallium arsenide, trapping in tiny confinements has already been shown to be possible. These structures are often referred to as “quantum dots”. Just like in an atom, where the electrons can only circle the nucleus on certain orbits, electrons in these are forced into discrete quantum states.” QBits 2 050616 Researchers-Break-Room-Temperature-Quantum-Bit-Storage-Record

In a tiny quantum prison, electrons behave quite differently as compared to their counterparts in free space. They can only occupy discrete energy levels, much like the electrons in an atom – for this reason, such electron prisons are often called “artificial atoms”.

Artificial atoms may also feature properties beyond those of conventional ones, with the potential for many applications for example in quantum computing. Such additional properties have now been shown for artificial atoms in the carbon material graphene.

The results have been published in the journal Nano Letters, the project was a collaboration of scientists from TU Wien (Vienna, Austria), RWTH Aachen (Germany) and the University of Manchester (GB).

Building Artificial Atoms

“Artificial atoms open up new, exciting possibilities, because we can directly tune their properties”, says Professor Joachim Burgdörfer (TU Wien, Vienna).

 

In semiconductor materials such as gallium arsenide, trapping in tiny confinements has already been shown to be possible. These structures are often referred to as “quantum dots”. Just like in an atom, where the electrons can only circle the nucleus on certain orbits, electrons in these are forced into discrete quantum states.

Even more interesting possibilities are opened up by using graphene, a material consisting of a single layer of , which has attracted a lot of attention in the last few years. “In most materials, electrons may occupy two different quantum states at a given energy. The high symmetry of the graphene lattice allows for four different quantum states. This opens up new pathways for quantum information processing and storage” explains Florian Libisch from TU Wien. However, creating well-controlled artificial atoms in graphene turned out to be extremely challenging.

'Artificial atom' created in graphene
(Left) Florian Libisch, explaining the structure of graphene. Credit: TU Wien

 

 

 

Cutting edge is not enough

There are different ways of creating artificial atoms: The simplest one is putting electrons into tiny flakes, cut out of a thin layer of the material. While this works for graphene, the symmetry of the material is broken by the edges of the flake which can never be perfectly smooth. Consequently, the special four-fold multiplicity of states in graphene is reduced to the conventional two-fold one.

Therefore, different ways had to be found: It is not necessary to use small graphene flakes to capture electrons. Using clever combinations of electrical and magnetic fields is a much better option. With the tip of a scanning tunnelling microscope, an electric field can be applied locally. That way, a tiny region is created within the graphene surface, in which low energy electrons can be trapped. At the same time, the electrons are forced into tiny circular orbits by applying a magnetic field. “If we would only use an electric field, quantum effects allow the electrons to quickly leave the trap” explains Libisch.

The artificial atoms were measured at the RWTH Aachen by Nils Freitag and Peter Nemes-Incze in the group of Professor Markus Morgenstern. Simulations and theoretical models were developed at TU Wien (Vienna) by Larisa Chizhova, Florian Libisch and Joachim Burgdörfer. The exceptionally clean graphene sample came from the team around Andre Geim and Kostya Novoselov from Manchester (GB) – these two researchers were awarded the Nobel Prize in 2010 for creating graphene sheets for the first time.

The new artificial atoms now open up new possibilities for many quantum technological experiments: “Four localized electron states with the same energy allow for switching between different quantum states to store information”, says Joachim Burgdörfer.

The electrons can preserve arbitrary superpositions for a long time, ideal properties for quantum computers. In addition, the new method has the big advantage of scalability: it should be possible to fit many such on a small chip in order to use them for quantum information applications.

Explore further: Physicists create artificial ‘graphene’

More information: Nils M. Freitag et al, Electrostatically Confined Monolayer Graphene Quantum Dots with Orbital and Valley Splittings, Nano Letters (2016). DOI: 10.1021/acs.nanolett.6b02548

 

 

Quantum dots with impermeable shell used as a powerful tool for “nano-engineering”


QDs Shell 081116 160811101152_1_540x360Images of ZnO quantum dots prepared by the Institute of Physical Chemistry of the Polish Academy of Sciences in Warsaw, taken by transmission electron microscopy. False colors.
Credit: IPC PAS

Unique optical features of quantum dots make them an attractive tool for many applications, from cutting-edge displays to medical imaging. Physical, chemical or biological properties of quantum dots must, however, be adapted to the desired needs.

Unfortunately, up to now quantum dots prepared by chemical methods could only be functionalized using copper-based click reactions with retention of their luminescence. This obstacle can be ascribed to the fact that copper ions destroy the ability of quantum dots to emit light. Scientists from the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) in Warsaw and the Faculty of Chemistry of the Warsaw University of Technology (FC WUT) have shown, however, that zinc oxide (ZnO) quantum dots prepared by an original method developed by them, after modification by the click reaction with the participation of copper ions, fully retain their ability to emit light.

“Click reactions catalyzed by copper cations have long attracted the attention of chemists dealing with quantum dots. The experimental results, however, were disappointing: after modification, the luminescence was so poor that they were just not fit for use. We were the first to demonstrate that it is possible to produce quantum dots from organometallic precursors in a way they do not lose their valuable optical properties after being subjected to copper-catalysed click reactions,” says Prof. Janusz Lewinski (IPC PAS, FC WUT).

Quantum dots are crystalline structures with size of a few nanometers (billionth parts of a meter). As semiconductor materials, they exhibit a variety of interesting features typical of quantum objects, including absorbing and emitting radiation of only a strictly defined energy. Since atoms interact with light in a similar way, quantum dots are often called artificial atoms. In some respects, however, quantum dots offer more possibilities than atoms. Optical properties of each dot actually depend on its size and the type of material from which it is formed. This means that quantum dots may be precisely designed for specific applications.

To meet the need of specific applications, quantum dots have to be tailored in terms of physico-chemical properties. For this purpose, chemical molecules with suitable characteristics are attached to their surface. Due to the simplicity, efficacy, and speed of the process, an exceptionally convenient method is the click reaction. Unfortunately, one of the most widely used click reactions takes place with the participation of copper ions, which was reported to result in the almost complete quenching of the luminescence of the quantum dots.

“Failure is usually a result of the inadequate quality of quantum dots, which is determined by the synthesis method. Currently, ZnO dots are mainly produced by the sol-gel method from inorganic precursors. Quantum dots generated in this manner are coated with a heterogeneous and probably leaky protective shell, made of various sorts of chemical molecules. During a click reaction, the copper ions are in direct contact with the surface of quantum dots and quench the luminescence of the dot, which becomes completely useless,” explains Dr. Agnieszka Grala (IPC PAS), the first author of the article in the Chemical Communications journal.

For several years, Prof. Lewinski’s team has been developing alternative methods for the preparation of high quality ZnO quantum dots. The method presented in this paper affords the quantum dots derived from organozinc precursors. Composition of the nanoparticles can be programmed at the stage of precursors preparation, which makes it possible to precisely control the character of their organic-inorganic interface.

“Nanoparticles produced by our method are crystalline and all have almost the same size. They are spherical and have characteristics of typical quantum dots. Every nanoparticle is stabilized by an impermeable protective jacket, built of organic compounds, strongly anchored on the surface of the semiconductor core. As a result, our quantum dots remain stable for a long time and do not aggregate, that is clump together, in solutions,” describes Malgorzata Wolska-Pietkiewicz, a PhD student at FC WUT.

“The key to success is producing a uniform stabilizing shell. Such coatings are characteristic of the ZnO quantum dots obtained by our method. The organic layer behaves as a tight protective umbrella protecting dots from direct influence of the copper ions,” says Dr. Grala and clarifies: “We carried out click reaction known as alkyne-azide cycloaddition, in which we used a copper(l) compound as catalysts. After functionalization, our quantum dots shone as brightly as at the beginning.”

Quantum dots keep finding more and more applications in various industrial processes and as nanomarkers in, among others, biology and medicine, where they are combined with biologically active molecules. Nanoobjects functionalized in this manner are used to label both individual cells as well as whole tissues. The unique properties of quantum dots also enable long-term monitoring of the labelled item. Commonly used quantum dots, however, contain toxic heavy metals, including cadmium. In addition, they clump together in solutions, which supports the thesis of the lack of tightness of their shells. Meanwhile, the ZnO dots produced by Prof. Lewinski’s group are non-toxic, they do not aggregate, and can be bound to many chemical compounds — so they are much more suitable for medical diagnosis and for imaging cells and tissues.

Research on the methods of production of functionalized ZnO quantum dots was carried out under an OPUS grant from the Poland’s National Science Centre.


Story Source:

The above post is reprinted from materials provided by Institute of Physical Chemistry of the Polish Academy of Sciences.Note: Content may be edited for style and length.


Journal Reference:

  1. Agnieszka Grala, Małgorzata Wolska-Pietkiewicz, Wojciech Danowski, Zbigniew Wróbel, Justyna Grzonka, Janusz Lewiński. ‘Clickable’ ZnO nanocrystals: the superiority of a novel organometallic approach over the inorganic sol–gel procedure. Chem. Commun., 2016; 52 (46): 7340 DOI:10.1039/C6CC01430E

University of Cambridge and IBM Collaborate on “Something Deep Within” ~ Nanocrystals grown in nanowires for new classes of high-performance, energy-efficient computing, communications, and environmental and medical sensing systems.


Deep Nanowires 081116 160729143208_1_540x360Top: High-resolution electron microscopy images of a nickel silicide rhombic nanocrystal embedded in a silicon nanowire prepared with gold silicide used as a catalyst. The images demonstrate the intimate interactions that arise at the interfaces of these nanomaterials. Bottom: The physical properties that arise from such complex nano-systems could be used in next-generation photodetectors, lasers, and transistors.
Credit: Image courtesy of Department of Energy, Office of Science
 

As any good carpenter knows, it’s often easier to get what you want if you build it yourself. An international team using resources at the Center for Functional Nanomaterials took that idea to heart. They wanted to tailor extremely small wires that carry light and electrons. They devised an approach that lets them tailor the wires through exquisite control over the structures at the nanoscale. New structures could open up a potential path to a wide range of smaller, lighter, or more efficient devices.

This development could lead to highly tailored nanowires for new classes of high-performance, energy-efficient computing, communications, and environmental and medical sensing systems. The resulting devices could lead to smaller electronics as well as improving solar panels, photodetectors, and semiconductor lasers.

Semiconducting nanowires have a wide range of existing and potential applications in optoelectronic materials, from single-electron transistors and tunnel diodes, to light-emitting semiconducting nanowires to energy-harvesting devices. An international collaboration led by the University of Cambridge and IBM has demonstrated a new method to create novel nanowires that contain nanocrystals embedded within them. They accomplished this by modifying the classic “vapor-liquid-solid” crystal growth method, wherein a liquid-phase catalyst decomposes an incoming gas-phase source and mediates the deposition of the solid, growing nanowire.

In this work, a bimetallic catalyst is used. The team showed that by appropriate thermal treatment, it is possible to crystallize a solid silicide structure within the liquid catalyst, and then attach the nanowire to the solid silicon in a controlled epitaxial fashion. The Center for Functional Nanomaterials’ Electron Microscopy Facility was employed to image the nanomaterials by high spatial-resolution, aberration-corrected transmission electron microscopy. As well, scientists used a first-of-its-kind direct electron detector to obtain high temporal-resolution images of the fabrication process. Incorporating these instruments with the expertise and insight of the scientific team led to fantastic, nanoscale control over these structures and presents notable potential for a broad range of potential devices, like photodetectors and single electron transistors.


Story Source:

The above post is reprinted from materials provided byDepartment of Energy, Office of Science. Note: Content may be edited for style and length.


Journal Reference:

  1. F. Panciera, Y.-C. Chou, M. C. Reuter, D. Zakharov, E. A. Stach, S. Hofmann, F. M. Ross. Synthesis of nanostructures in nanowires using sequential catalyst reactions. Nature Materials, 2015; 14 (8): 820 DOI:10.1038/nmat4352

DOE – Brookhaven: Smarter self-assembly opens new pathways for nanotechnology – Essential to Fully Exploit the Nanoscale for ‘Next Generation’ Electronic Devices


Smart Self Assem 081116 smarterselfaTo continue advancing, next-generation electronic devices must fully exploit the nanoscale, where materials span just billionths of a meter. But balancing complexity, precision, and manufacturing scalability on such fantastically small scales is inevitably difficult. Fortunately, some nanomaterials can be coaxed into snapping themselves into desired formations-a process called self-assembly.

Scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have just developed a way to direct the self-assembly of multiple molecular patterns within a single material, producing new nanoscale architectures. The results were published in the journal Nature Communications.

“This is a significant conceptual leap in self-assembly,” said Brookhaven Lab physicist Aaron Stein, lead author on the study. “In the past, we were limited to a single emergent pattern, but this technique breaks that barrier with relative ease. This is significant for basic research, certainly, but it could also change the way we design and manufacture electronics.”

Microchips, for example, use meticulously patterned templates to produce the nanoscale structures that process and store information. Through self-assembly, however, these structures can spontaneously form without that exhaustive preliminary patterning. And now, self-assembly can generate multiple distinct patterns-greatly increasing the complexity of nanostructures that can be formed in a single step.

“This technique fits quite easily into existing microchip fabrication workflows,” said study coauthor Kevin Yager, also a Brookhaven physicist. “It’s exciting to make a fundamental discovery that could one day find its way into our computers.”

The experimental work was conducted entirely at Brookhaven Lab’s Center for Functional Nanomaterials (CFN), a DOE Office of Science User Facility, leveraging in-house expertise and instrumentation.

Smarter self-assembly opens new pathways for nanotechnology
Electron beam lithography is used to adjust the spacing and thickness of line patterns etched onto a template (lower layer). These patterns drive a self-assembling block copolymer (top layer) to locally form different types of patterns, …more

 

Cooking up organized complexity

The collaboration used block copolymers-chains of two distinct molecules linked together-because of their intrinsic ability to self-assemble.

“As powerful as self-assembly is, we suspected that guiding the process would enhance it to create truly ‘responsive’ self-assembly,” said study coauthor Greg Doerk of Brookhaven. “That’s exactly where we pushed it.”

To guide self-assembly, scientists create precise but simple substrate templates. Using a method called electron beam lithography-Stein’s specialty-they etch patterns thousands of times thinner than a human hair on the template surface. They then add a solution containing a set of block copolymers onto the template, spin the substrate to create a thin coating, and “bake” it all in an oven to kick the molecules into formation. Thermal energy drives interaction between the block copolymers and the template, setting the final configuration-in this instance, parallel lines or dots in a grid.

“In conventional self-assembly, the final nanostructures follow the template’s guiding lines, but are of a single pattern type,” Stein said. “But that all just changed.”

Smarter self-assembly opens new pathways for nanotechnology
Brookhaven National Laboratory Center for Functional Nanomaterials researchers Gwen Wright and Aaron Stein are at the electron beam lithography writer in the CFN cleanroom. Credit: Brookhaven National Laboratory

Lines and dots, living together

The collaboration had previously discovered that mixing together different allowed multiple, co-existing line and dot nanostructures to form.

“We had discovered an exciting phenomenon, but couldn’t select which morphology would emerge,” Yager said. But then the team found that tweaking the substrate changed the structures that emerged. By simply adjusting the spacing and thickness of the lithographic line patterns-easy to fabricate using modern tools-the self-assembling blocks can be locally converted into ultra-thin lines, or high-density arrays of nano-dots.

“We realized that combining our self-assembling materials with nanofabricated guides gave us that elusive control. And, of course, these new geometries are achieved on an incredibly small scale,” said Yager.

“In essence,” said Stein, “we’ve created ‘smart’ templates for nanomaterial self-assembly. How far we can push the technique remains to be seen, but it opens some very promising pathways.”

Gwen Wright, another CFN coauthor, added, “Many nano-fabrication labs should be able to do this tomorrow with their in-house tools-the trick was discovering it was even possible.”

The scientists plan to increase the sophistication of the process, using more complex materials in order to move toward more device-like architectures.

“The ongoing and open collaboration within the CFN made this possible,” said Charles Black, director of the CFN. “We had experts in , electron beam lithography, and even electron microscopy to characterize the materials, all under one roof, all pushing the limits of nanoscience.”

Explore further: Copolymers block out new approaches to microelectronics at NIST

More information: A. Stein et al, Selective directed self-assembly of coexisting morphologies using block copolymer blends, Nature Communications (2016). DOI: 10.1038/ncomms12366

 

Picoscale precision though ultrathin film piezoelectricity: Opportunity for next-generation sensors and microelectromechanical devices


Piezo 081116 2-schematicill.jpgFig. 1. Schematic illustration of local characterization of in-plane piezoelectricity and vertical piezoelectricity. In-plane piezoelectricity (piezo) (d11, d22) of ultrathin materials is the planar electromechanical couple behavior, where …more

Piezoelectricity (aka the piezoelectric effect) occurs within certain materials – crystals (notably quartz), some ceramics, bone, DNA, and a number of proteins – when the application of mechanical stress or vibration generates electric charge or alternating current (AC) voltage, respectively. (Conversely, piezoelectric materials can vibrate when AC voltage is applied to them.) The piezoelectric effect has a significant range of uses, including sound production and detection, generation of high voltages and electronic frequencies, atomic resolution imaging technologies (e.g., scanning tunneling and atomic force microscopy), and actuators for highly accurate positioning of nanoscale objects – the last being crucial for fundamental research and industrial applications.

That being said, subatomic scale positioning still presents a number of challenge. Recently, however, researchers at Nanyang Technological University, Singapore, Chinese Academy of Sciences, Suzhou, and Duke University, Durham demonstrated vertical piezoelectricity at the atomic scale (three to five space lattices) using ultrathin cadmium sulfide (CdS) films. The researchers determined a vertical piezoelectric coefficient (d33) three times that of bulk CdS using in situ scanning Kelvin force microscopy and single and dual ac resonance tracking piezoelectric force microscopy, leading them to conclude that their findings have a number of critical roles in the design of next-generation sensors and microelectromechanical devices.

Prof. Zheng Liu discussed the paper that he, Dr. Ting Zhang and their colleagues published in Science Advances, describing a series of challenges they faced starting with using chemical vapor deposition to synthesize 2~3 nm cadmium sulfide (CdS) thin films. “The vertical piezoelectricity, or d33, is the key parameter in piezoelectric materials for the fabrication of actuators used to position objects with extreme accuracy – down to the atomic scale in a broad range of cutting-edge equipment such as atomic force microscopy and scanning tunneling microscopy,” Liu tells Phys.org. “Moreover, high-performance ultrathin piezoelectric materials are crucial for the constructing ultra-high resolution and flexible electromechanically coupled devices.”
Prior to this study, Liu points out, only a few studies reported the synthesis of atomic thin piezoelectric materials by a wet chemical method, examples of which include CdS and cadmium selenide (CdSe) nanoplatelets. “It’s a significant challenge to produce high-quality and atom-thin piezoelectric materials,” he adds. “In this research, the main challenge in synthesizing ultrathin piezoelectric CdS films via chemical vapor deposition” (or CVD) “lays in the selection of precursors and how to optimize the reaction parameters, such as growing temperature and time.”

 
The scientists were then faced with demonstrating d33 vertical piezoelectricity at the atomic scale using ultrathin cadmium sulfide thin films. “When the thickness of materials reaches the nanoscale level,” Liu explains, “it’s very difficult to verify the piezoelectric effect and determine its values because of the coupling effect from the substrate – and surface geometries may affect the measurements at atomic limits as well.” For example, he illustrates, sample surface roughness reaches tens of picometers, which is the same scale with the vertical electromechanical response for materials.

Piezo 2 081116 spectroscopi

Fig. 3. Spectroscopic characterization of CdS thin film. (A) Energy (E) band structure in the vicinity of the Γ-point of the Brillouin zone, showing the photon emission process. (B and C) PL spectrum of CdS thin film from points i and ii …more

Lastly – and reminiscent of the challenge in demonstrating d33 vertical piezoelectricity at the atomic scale using CdS thin films – the researchers had to determine the CdS film vertical piezoelectric coefficient with in situ scanning Kelvin force microscopy (SKFM) and single and dual AC resonance tracking piezoelectric force microscopy (DART-PFM). “The quality of ultrathin piezoelectric CdS is the key to obtaining a reliable vertical piezoelectric coefficient.” Liu notes. “Some characterization tools like Raman and photoluminescence spectroscopies can help us to identify the CdS sample and confirm its high quality. Also, because of the geometrical vibrations of the CdS samples, the atomic force microscopy characterization should be carefully carried out in order to make sure our conclusions are solid.” This required the researchers to examine many SKFM and DART-PFM samples using to reach a solid conclusion about vertical piezoelectric behavior in CdS ultrathin films.

 
Liu comments that addressing these challenges required innovative techniques. “For the first time, we successfully synthesized high-quality atomic thin CdS films using CVD, and we demonstrated vertical piezoelectricity of these films at the atomic scale of 3~5 space lattices” (a space, or crystal, lattice being a periodically repeating two- or three-dimensional array of points or particles) “and observed the vertical piezoelectric domains. More importantly,” Liu continues, “our work shows an enhanced vertical piezoelectricity in CdS ultrathin films at a level three times larger than the CdS bulk counterpart, as well as higher than most of traditional piezoelectric materials.” These results imply non-trivial piezoelectric behavior at atomic limits for a certain class of materials – which has not yet been well explored – and inspires the search for two-dimensional free-standing layered piezoelectric materials that are only one atom thick.

 
Liu points out that their findings shed light on the design of next-generation sensors, actuators and microelectromechanical devices, in that piezoelectric materials are the most important component for such devices. Specifically, he says that their findings provide the opportunity for next-generation sensors and microelectromechanical devices in three ways:

 
Flexibility: Ultrathin piezoelectric material materials are naturally like two-dimensional materials in being flexible, allowing them to be conformably used for more complicated electromechanical devices.
Miniaturization: Ultrathin piezoelectric material materials are a perfect candidate for the fabrication of reduced size, highly integrated devices, especially for mobile phone and wearable devices.
Inspiration: The study’s results will inspire the development of other ultrathin piezoelectric materials, especially two-dimensional piezoelectric materials.

Piezo 3 081116 noncontactsk

Fig. 4. Noncontact SKFM and standard contact PFM investigation for CdS thin film. (A and B) Schematic illustration of SKFM (A) and PFM (B) measurements. (C) Band diagram of tip and sample when they are electrically separated (top graph) and …more

Liu illustrates these points by listing potential examples of such devices – for example, atomically thin piezoelectric devices – and their applications. “For instance, using CdS ultrathin films, the most accurate probe or stage ever fabricated may be achievable, allowing researchers and engineers to manipulate atoms or position tips in atomic force, scanning electron and transmission electron microscopy.

In other words, CdS ultrathin films will extend our capability to see and manipulate our world in an extreme way.” Of more importance, he adds, such ultrathin piezoelectric devices can be integrated into equipment like autocollimators and Michelson interferometers used in, for example, cold atom studies, the verification of the gravitational inverse square law at short range, and even the detection of gravitational waves.
The study also reports the in situ measurement of the ultrathin CdS film vertical piezoelectric coefficient d33, determining the film coefficient to be approximately three times larger than that of bulk CdS. “This value is pretty big for atomically thin materials,” Liu explains. “It means that we can get a large voltage change when small pressure or deformation is applied. This makes the material a great candidate constructing sensitive and ultrathin mechanical sensors.”

Piezo 4 081116 1-simulationof
Fig. 6. Simulation of vertical piezoelectricity and subatomic deformation actuator. (A) Three-dimensional image of potential drop on CdS film. (B) Scanning electron microscopy image of a conductive tip for PFM characterization. (C and D) …more

The researchers concluded that contact piezoresponse force microscopy (PFM) – which uses a conductive tip to apply a highly localized electric field that allows imaging and manipulation of piezoelectric ferroelectric materials – could significantly change the surface potential of a CdS ultrathin film by applying stress to its surface. “Typically, applying mechanical stress to a piezoelectric material will generate electric charge that accumulates at the surface of the material, which is how we identify the piezoelectric materials,” Liu tells Phys.org. “We therefore believe that this results from piezoelectric polarizations giving rise to a large piezoelectric potential, in turn leading to a remarkable spatial separation of electrons and holes.” In this case, electrons generated by the piezoelectric effect will be trapped into the silicon dioxide (SiO2) dielectric layers, while the holes will be trapped inside the crystal boundary of the CdS films.

 
The scientists state that their work may pave a way to the synthesis of ultrathin lattice scale nanomaterials using CVD method, which is a low-cost method for producing high quality samples. In addition, Liu notes, the materials provided by their study will enable the high-integrated and multi-functional devices by simply coating or transferring the film to the device. “For actuator applications, our work will promote next generation actuators with extreme resolution for their potential use in characterization tools such as ultra-high resolution microscopy; for atom manipulation and fabrication; or potentially for the detection of ultra-low deformation in, for example, cold atom studies, verification of the gravitational inverse square law at short range, and even the detection of gravitational waves.”

 
Moving forward, Liu says, the scientists will determine the relationship between the vertical piezoelectric coefficient d33 and the thickness of CdS at atomic scales. “Well also synthesize other piezoelectric, ferroelectric and layered piezoelectric/ferroelectric ultrathin materials, and explore their electromechanical properties.” Based on this material and micro/nano-manufacture technology, the researchers hope to design and fabricate next-generation actuators for accurate positioning of minute objects, such as nanoparticles at subatomic scales, using their novel materials.

 
In addition, the large vertical piezoelectric coefficient d33 makes this material promising to construction of ultrathin and sensitive pressure sensors for detecting miniscule forces. If the low detection limit of sensor reaches to nanoscale levels, the device could monitor single biological cell migration.

 
“Our study will inspire material scientists to hunt for other non-trivial ultrathin or layered piezoelectric or ferroelectric materials,” Liu tells Phys.org. “Engineers can employ our CdS ultrathin films to design and fabricate novel microelectromechanical systems,” or MEMS, “and nanoelectromechanical systems,” or NEMS, “with high-integration and multi-functionalities, and may benefit when developing cutting-edge scientific instruments. Furthermore,” he concludes, “novel and flexible consumer electronic devices can be developed based on our study.”

Explore further: Graphene’s piezoelectric promise

 
More information: X. Wang et al, Subatomic deformation driven by vertical piezoelectricity from CdS ultrathin films, Science Advances 01 Jul 2016, Vol. 2, no. 7, e1600209, doi:10.1126/sciadv.1600209

 
Journal reference: Science Advances