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Astrobiologists and planetary scientists agree that a planet’s distance from its parent star is of paramount importance for creating those optimum conditions. A new study by Arizona State University researchers suggests that the host star’s chemical makeup can also impact conditions of habitability of planets that orbit them. Photo by: NASA

Newly published research from scientists at ASU suggests that the host star’s chemical makeup has a substantial impact on the evolution of the host star and the extent of its habitable zone.

The search for potentially habitable planets involves discussion of what is sometimes referred to as the Goldilocks Zone – the relatively thin band in a solar system in which conditions on a planet can support life.

Astrobiologists and planetary scientists agree that a planet’s distance from its parent star is of paramount importance for creating those optimum conditions – like Goldilocks’ porridge, it has to be just right.

A new study by Arizona State University researchers suggests that the host star’s chemical makeup also can impact conditions of habitability of planets that orbit them. The team’s paper, published in the August issue of The Astrophysical Journal Letters, demonstrates that subtle differences in a star’s internal chemistry can have huge effects on a planet’s chances of long-term habitability.

“We have identified changes in the ratios of different elements as particularly important for a given solar system’s habitability,” says Patrick Young, an assistant professor in ASU’s School of Earth and Space Exploration and lead author on the paper. “The more abundant elements carbon, oxygen, silicon, magnesium and sodium are particularly important. The greater the abundances of these four elements in a star, the slower it, and the location of its Goldilocks Zone, will evolve.”

As a star evolves, it becomes brighter, causing the habitable zone to move outwards through its solar system. The team’s study indicates that a greater abundance of oxygen, carbon, sodium, magnesium and silicon should be a plus for an inner solar system’s long-term habitability because the abundance of these elements make the star cooler and cause it to evolve more slowly, thereby giving planets in its habitable zone more time to develop life as we know it.

To explore whether stellar internal chemistr industrial cellular vpn routerIndustrial 3g router  y causes significant changes in the evolution of stars and therefore their habitable zones, Young and his colleagues, graduate students Mike Pagano and Kelley Liebst, did simulations of stars that are like our sun.

“We used spectra from 145 broadly sun-like stars targeted by planet to estimate the amount of variation in the abundance ratios of elements,” explains Pagano, who is a graduate student in the School of Earth and Space Exploration astrophysics program. “For each model, we varied the amount of one element to the extremes of variation we estimated from our analysis of the observations.”

The largest changes, unsurprisingly, arise from variation in oxygen.

“Oxygen is the most abundant element in the universe besides hydrogen and helium, so a change in the oxygen abundance results in a significant change in the total amount of heavy elements in the star,” Pagano said. “Oxygen turns out to be highly  industrial IoT gateway variable in abundance. The effect of increased heavy element abundance on a star is to make it harder for the energy produced by nuclear fusion to escape the star. This means less energy needs to be produced to support the star, and it can live longer.”

The stellar abundance of oxygen seems crucial in determining how long planets stay in the habitable zone around their host star. If there had been less oxygen in the Sun’s chemical makeup, for example, Earth likely would have been pushed out of the Sun’s habitable zone about a billion years ago, well before complex organisms evolved. Considering the first complex multicellular organisms only arose about 650 million years ago, such a move would have likely destroyed any chance of complex life taking hold on Earth.

Planets being searched for signs of life may be about to leave their habitable zones or only have just entered them.

“Habitability is very difficult to quantify because it depends on a huge number of variables, some of which we have yet to identify,” says Young. “It also depends on the definition of habitable that we choose to use. We chose to use a relatively simple model that predicts whether a planet can sustain liquid water on its surface with reasonable assumptions about planetary atmospheres.”

Image: NASA

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Scientists are working on a Entry level Industrial Router   directional dark matter detector that will use strands of DNA and gold in order to detect the elusive non-baryonic matter. A combined team of physicists and biologists are collaborating in order to create a suitable detector that will try and find dark matter, which accounts for much of the universe’s mass.

Dark matter cannot be seen but its effects can be inferred thanks to its gravitational influence on baryonic matter and the structure of the universe. Most of the models of dark matter suggest that it exerts itself on galaxy clusters. Earth is hypothetically surrounded by dark matter, and since it rotates around Sol, which it is currently traveling toward the constellation Cygnus as the Sun rotates around the galactic center, Earth should experience a kind of dark matter headwind of sorts. The researchers published their findings via arXiv.

This headwind, or tailwind depending on Earth’s orbit around the sun, emanates from the direction of Cygnus. Many different research groups are working on dark matter detectors, deep in underground caverns using expensive sensors, hiding them from radiation that would pollute the signal. The new team, including astrophysicist Katherine Freese from the University of Michigan and geneticist George Church from Harvard, believes they can overcome the hurdles using DNA to find a specific kind of dark matter particles, WIMPs, or weakly interacting massive particles.

Their detector uses a thin gold sheet with many single strands of DNA hanging from i touchscreen vending  t. It’s hypothesized that particles of dark matter will smash into the heavy gold nucleus, pushing it out of the gold sheet and into the DNA “forest”. This will knock out some of the DNA strands which in turn fall into a collection tray. Each of them has a unique identifier, so it will allow researchers to reconstruct the path of the gold particle with a high degree of precision. The detector has hundreds of thousands of these sheets placed between Mylar sheets. It uses under a kilogram of gold and 100g of single-strand DNA on a square-meter array.

DNA can be used in this process because it will separate the structure vertically with nanometer resolution, up to the nearest nucleotide, the smallest structural unit of DNA. It is better by many orders of magnitude than other detectors. The detector can also work at room temperature and needs no expensive cooling. The Mylar sheets make the detector directional. Higher energy nuclei from background radiation will pass through several of the leaves of Mylar, allowing their identification and exclusion from the process.

This unconventional approach has numerous challenges. It’s not clear how the rapidly-moving gold nuclei will interact with the DNA. This will need to be further researched before the detector is built. Also, making the stra industrial VPN gatewaynds long enough will be challenging. At the moment, DNA strands have around 250 bases. The detector will needs strands with at least 10,000 bases in order to absorb all of the energy of the gold nucleus. The strands would also have to be straightened, and not curl up.

[via Wired UK]

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Simulations by Rice University scientists show how carbon nanomaterials may be optimized to replace expensive platinum in cathodes foLine Monitoringr electricity-generating fuel cells for transportation and other applications. Credit: Yakobson Research Group/Rice University

New research from Rice University shows that nitrogen-doped carbon nanotubes or modified graphene nanoribbons may be suitable replacements for platinum for fast oxygen reduction, the key reaction in fuel cells that transform chemical energy into electricity.

The findings are from computer simulations by Rice scientists who set out to see h cost-effective M2M router  ow carbon nanomaterials can be improved for fuel-cell cathodes. Their study reveals the atom-level mechanisms by which doped nanomaterials catalyze oxygen reduction reactions (ORR).

The research appears in the Royal Society of Chemistry journal Nanoscale.

Theoretical physicist Boris Yakobson and his Rice colleagues are among many looking for a way to speed up ORR for fuel cells, which were discovered in the 19th century but not widely used until the latter part of the 20th. They have since powered transportation modes ranging from cars and buses to spacecraft.

The Rice researchers, including lead author and former postdoctoral associate Xiaolong Zou and graduate student Luqing Wang, used computer simulations to discover why graphene nanoribbons and carbon nanotubes modified with nitrogen and/or boron, long stu dsl  died as a substitute for expensive platinum, are so sluggish and how they can be improved.

Doping, or chemically modifying, conductive nanotubes or nanoribbons changes their chemical bonding characteristics. They can then be used as cathodes in proton-exchange membrane fuel cells. In a simple fuel cell, anodes draw in hydrogen fuel and separate it into protons and electrons. While the negative electrons flow out as usable current, the positive protons are drawn to the cathode, where they recombine with returning electrons and oxygen to produce water.

The models showed that thinner carbon nanotubes with a relatively high concentration of nitrogen would perform best, as oxygen atoms readily bond to the carbon atom nearest the nitrogen. Nanotubes have an advantage over nanoribbons because of their curvature, which distorts chemical bonds around their circumference and leads to easier binding, the researchers found.

The tricky bit is making a catalyst that is neither too strong nor too weak as it bonds with oxygen. The curve of the nanotube provides a way to tune the nanotubes’ binding energy, according to the researchers, who determined that “ultrathin” nanotubes with a radius between 7 and 10 angstroms would be ideal. (An angstrom is one ten-billionth of a meter; for comparison, a typical atom is about 1 angstrom in diameter.)

They also showed co-doping graphene nanoribbons with nitrogen and boron enhances the oxygen-absorbing abilities of ribbons with zigzag edges. In this case, oxygen finds a double-bonding opportunity. First, they attach directly to positively charged boron-doped sites. Second, they’re drawn by carbon atoms with high spin charge, which interacts with the oxygen atoms’ spin-polarized electron orbitals. While the spin effect enhances adsorption, the binding energy remains weak, also achieving a balance that allows for good catalytic performance.

The researchers showed the same catalytic principles held true, but to lesser effect, for nanoribbons with armchair edges.

“While doped nanotubes show good promise, the best performance can probably be achieved at the nanoribbon zigzag edges where nitrogen substitution can expose the so-called pyridinic nitrogen, which has known catalytic activity,” Yakobson said.

“If arranged in a foam-like configuration, such material can approach the efficiency of platinum,” Wang said. “If price is a consideration, it would certainly be competitive.”

Publication: Xiaolong Zou, et al., “Mechanisms of the oxygen reduction reaction on B- and/or N-doped carbon nanomaterials with curvature and edge effects,” Nanoscale, 2018; DOI:10.1039/C7NR08061A

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This MIT device, based on modified carbon nanotubes, can detect amines produced by decaying meat.

Chemists at MIT have developed an inexpensive, portable sensor that can detect gases emitted by rotting meat, allowing consumers to determine whether the meat in their grocery store or refrigerator is safe to eat.

The sensor, which consists of chemically modifie Vending Telemetry  d carbon nanotubes, could be deployed in “smart packaging” that would offer much more accurate safety information than the expiration date on the package, says Timothy Swager, the John D. MacArthur Professor of Chemistry at MIT.

It could also cut down on food waste, he adds. “People are constantly throwing things out that probably aren’t bad,” says Swager, who is the senior author of a paper describing the new sensor this week in the journal Angewandte Chemie.

The paper’s lead author is graduate student Sophie Liu. Other authors are former lab technician Alexander Petty and postdoc Graham Sazama.

The sensor is similar to other carbon nanotube devices that Swager’s lab has developed in recent years, including one that detects the ripeness of fruit. All of these devices work on the same principle: Carbon nanotubes can be chemically modified so that their ability to carry an electric current changes in the presence of a particular gas.

In this ca branch networking  se, the researchers modified the carbon nanotubes with metal-containing compounds called metalloporphyrins, which contain a central metal atom bound to several nitrogen-containing rings. Hemoglobin, which carries oxygen in the blood, is a metalloporphyrin with iron as the central at Intelligent Traffic Enforcement  om.

For this sensor, the researchers used a metalloporphyrin with cobalt at its center. Metalloporphyrins are very good at binding to nitrogen-containing compounds called amines. Of particular interest to the researchers were the so-called biogenic amines, such as putrescine and cadaverine, which are produced by decaying meat.

When the cobalt-containing porphyrin binds to any of these amines, it increases the electrical resistance of the carbon nanotube, which can be easily measured.

“We use these porphyrins to fabricate a very simple device where we apply a potential across the device and then monitor the current. When the device encounters amines, which are markers of decaying meat, the current of the device will become lower,” Liu says.

In this study, the researchers tested the sensor on four types of meat: pork, chicken, cod, and salmon. They found that when refrigerated, all four types stayed fresh over four days. Left unrefrigerated, the samples all decayed, but at varying rates.

There are other sensors that can detect the signs of decaying meat, but they are usually large and expensive instruments that require expertise to operate. “The advantage we have is these are the cheapest, smallest, easiest-to-manufacture sensors,” Swager says.

“There are several potential advantages in having an inexpensive sensor for measuring, in real time, the freshness of meat and fish products, including preventing foodborne illness, increasing overall customer satisfaction, and reducing food waste at grocery stores and in consumers’ homes,” says Roberto Forloni, a senior science fellow at Sealed Air, a major supplier of food packaging, who was not part of the research team.

The new device also requires very little power and could be incorporated into a wireless platform Swager’s lab recently developed that allows a regular smartphone to read output from carbon nanotube sensors such as this one.

The researchers have filed for a patent on the technology and hope to license it for commercial development. The research was funded by the National Science Foundation and the Army Research Office through MIT’s Institute for Soldier Nanotechnologies.

Publication: Sophie F. Liu, et al., “Single-Walled Carbon Nanotube/Metalloporphyrin Composites for the Chemiresistive Detection of Amines and Meat Spoilage,” Angewandte Chemie International Edition, 2015; DOI: 10.1002/anie.201501434

Image: Sophie Liu

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Atomic resolution scanning transmission electron microscopy images and electron diffraction patterns, arranged on a rendering of a battery, show how the structure of lithium-rich and manganese-rich transition metal oxides used inside battery cathodes changes with composition. The images also show how the surface of the cathode has a different structure than the interior. Credit: Berkeley Lab

Lithium-ion batteries are widely used in home electronics and are now being used to power electric vehicles and store energy for the power grid. But their limited number of recharge cycles and tendency to degrade in capacity over their lifetime have spurred a great deal of research into improving the technology.

An international team led by researchers from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) used advanced techniques in electron microscopy to show how the ratio of materials that make up a lithium-ion battery electrode affects its structure at the atomic level, and how the surface is very different from the rest of the material. The work was published in the journal Energy & Environmental Science.

Knowing how the internal and surface structure of a battery material changes over a wide range of chemical compositions will aid future studies on cathode transformations and could also lead to the development of new battery materials.

“This finding could change the way we look at phase transformations within the cathode and the resulting loss of capacity in this class of material,” said Alpesh Khushalchand Shukla, a scientist at Berkeley Lab’s Molecular Foundry, and lead author of the study. “Our work shows that it is extremely important to completely characterize a new material in its pristine state, as well as after cycling, in order to avoid misinterpretations.”

Previous work by researchers at the Molecular Foundry, a research center specializing in nanoscale science, revealed the structure of cathode materials containing “excess” lithium, resolving a longstanding debate.

Using a suite of electron microscopes both at the National Center for Electron Microscopy (NCEM), a Molecular Foundry facility, and at SuperSTEM, the National Research Facility for Advanced Electron Microscopy in Daresbury, U.K., the research team found that while the atoms throughout the interior of the cathode material remained in the same structural pattern across all compositions, decreasing the amount of lithium caused an increase in randomness in the position of certain atoms within the structure.

By comparing different compositions of cathode material to battery performance, the researchers also demonstrated it was possible to optimize battery performance in relation to capacity by using a lower ratio of lithium to other metals.

The most surprising finding was that the surface structure of an unused cathode is very different from the interior of the cathode. A thin layer of material on the surface possessing a different structure, called the “spinel” phase, was found in all of their experiments. Several previous studies had overlooked that this layer might be present on both new and used cathodes.

By systematically varying the ratio of lithium to a transition metal, like trying different amounts of ingredients in a new cookie recipe, the research team was able to study the relationship between the surface and interior structure and to measure the electrochemical performance of the material. The team took images of each batch of the cathode materials from multiple angles and created complete, 3-D renderings of each structure.

“Obtaining such precise, atomic-level information over length scales relevant to battery technologies was a challenge,” said Quentin Ramasse, Director of the SuperSTEM Laboratory. “This is a perfect example of why the multiple imaging and spectroscopy techniques available in electron microscopy make it such an indispensab healthcare  le and versatile tool in renewable energy research.”

The researchers also used a newly developed technique called 4-D scanning transmission electron microscopy (4-D STEM). In trans 3g modem  mission electron microscopy (TEM), images are formed after electrons pass through a thin sample. In conventional scanning transmission electrode microscopy (STEM), the electron beam is focused down to a very small spot (as small as 0.5 nanometers, or billionths of a meter, in diameter) and then that spot is scanned back and forth over the sample like a mower on a lawn.

The detector in conventional STEM simply counts how many electrons are scattered (or not scattered) in each pixel. However, in 4D-STEM, the researchers use a high-speed electron detector to record where each electron scatters, from each scanned point. It allows researchers to measure the local structure of their sample at high resolution over a large field of view.

“The introduction of high-speed electron cameras allows us to extract atomic-scale information from very large sample dimensions,” said Colin Ophus, a research scientist at NCEM. “4D-STEM experiments mean we no longer need to make a tradeoff between the smallest features we can resolve and the field-of-view that we are observing – we can analyze the atomic structure of the entire particlPower Fault Detectione at once.”

Berkeley Lab’s Molecular Foundry is a DOE Office of Science User.

This work was supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy, Office of Basic Science, and Small Business Voucher Pilot Program; Envia Systems; and the U.K.’s Engineering and Physical Science Research Council.

Publication: Alpesh Khushalchand Shukla, et al., “Effect of composition on the structure of lithium- and manganese-rich transition metal oxides,” Energy Environ. Sci., 2018, doi:10.1039/C7EE02443F

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Biochemical reactions behave differently when subjected to intracellular crowding Image: James Cridland/Flickr

Molecular crowding inside cells is a critical factor that is sometimes overlooked in the lab. Biochemical reactions are drastically different in tighter spaces, resulting in significant physical and chemical consequences.

The reductive approach to chemical reactions is attractive to scientists, as it’s convenient when interpreting results and easier to work with. However, if a more simplistic experimental framework is adopted, these tests may overlook the critical aspect of intracellular crowding.

Molecular Crowding Effects in the T-cell Signaling Pathway, via Jonathan Eide

If there is less space available for each molecule, the resulting effective concentration is boosted, increasing the chemical potential. When more molecules are crammed together, there is also the possibility that reactants will link up, causing the chemical potential to respond drastically.

There is also a slowdow Vending Telemetry  n of molecular diffusion, particularly for larger molecules. Lower rates of diffusion imply that diffusion-limited reactions happen slower, especially those involving larger constituents. These two consequences, h plc programming  igher chemical potentials and lower diffusion rates, counteract each other when it comes to intermolecular reactions, making the resulting reaction rate difficult to predict. However, t Industrial IoT Router/Gateway  here usually is an optimal spot with enough coziness to encourage reactivity, but not too much to gum up the works.

The effects on thermodynamics and kinetics are so far ranging that estimates of reaction rates and equilibria made in uncrowded solutions differ by orders of magnitude from those of the same reactions operating under crowded conditions.

[via Wired]

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The stuff that quantum memories are made of: an international team of physicists has succeeded, for the first time, in storing a quantum bit in a diamond for longer than one second at room temperature. The researchers did not use a natural diamond like the one shown here, however, neither was it cut. They produced their diamond artificially by depositing carbon containing one hundredth of a percent of the heavy carbon isotope C-13 and a small quantity of nitrogen from the gas phase onto a substrate. The diamond they obtained in this way had an edge length of a few millimeters. iStockphoto

A team of scientists successfully stored a quantum bit in a diamond crystal for more than a second at room temperature, an improvement of almost thousand-fold, and believe that the lifetime of the qubit can be increased to a maximum of 36 hours.

Credit cards which are completely fraud-proof and passports which cannot be forged: quantum physics could make both of these possible. This is explained by the fact that the quantum mechanical state of a particle, an atomic nucleus, for example, can be neither copied nor read out correctly without additional information which only authorized users of possible cards have. Accordingly, if a credit card were to contain a quantum memory, it would be protected against misuse. Although physicists have already developed methods to write quantum states into different types of memory and read them out again, the problem is either that these methods work only just above absolute zero temperature which excludes routine use – or that the quantum information stored is lost after only a few milliseconds. Researchers at Harvard University in Cambridge near Boston, the Max Planck Institute of Quantum Optics in Garching, and Caltech in Pasadena have now successfully stored a quantum state in a diamond crystal for more than a second at room temperature. The researchers even believe that a storage time of one-and-a-half days is possible if they improve their method.

A quantum memory uses a more complex version of the smallest unit of information in a conventional computer memory, the bit, namely the so-called quantum bit, qubit for short. Whereas the bit can take only one of two possible states at any point in time (where one is designated with “0” and the other with “1”), the qubit can literally take both states simultaneously. Its information content consists in the respective weight of “0” and “1”: the qubit can consist of 20 percent “0” and 80 percent “1”, for example. Any ratio which sums up to yield 100 percent is possible. This means that many values can be stored in a single qubit.

Physicists use various physical systems to store qubits, for example atoms, which are located in a lattice of crossed laser beams similar to eggs in an egg carton, or atomic nuclei in a solid body. In future, a quantum memory of several qubits could be used for forgery-proof data storage, as the so-called no-cloning theorem of quantum physics forbids the copying of quantum states. In addition, it is only possible to read out the contents if one knows the parameters with which the memory has been written, such as the polarization direction of light signals.

A quantum memory must be isolated from the environment, but not completely

An almost insurmountable obstacle prevents its practical implementation. A quantum memory must fulfil two conflicting criteria: on the one hand, it must be isolated from the environment as much as possible so that the stored qubits are not destroyed by external magnetic fields, light particles or similar environmental influences. On the other hand, it must be able to exchange information with this very same environment; otherwise it would not possible to write information into the memory and read it out again. Thus the complete isolation of the qubits does not achieve the objective.

The international group of researchers from Harvard Unive Smart Vending  rsity, the Max Planck Institute of Quantum Optics and Caltech has now successfully reconciled the conflicting factors to such a degree that a qubit in an artificial diamond crystal can remain stable for more than a second, even at room temperature. Previously, this type of qubit was preserved for only a few thousandths of a second. “We’ve achieved this almost thousand-fold improvement with relatively little experimental effort,” says David Hunger from the Max Planck Institute of Quantum Optics in Garching. The scientists essentially needed a green laser, fast-switching sources for microwaves and radio frequencies, and a highly sensitive detector that is capable of detecting individual light particles.

For the qubit, the researchers used the nucleus of a carbon atom, or to be more precise, the C-13 carbon isotope; its nucleus has a so-called nuclear spin, which generates a magnetic moment. The C-13 nucleus thus behaves like a tiny bar magnet that can align itself parallel or anti-parallel to an externally applied magnetic field. These two states form the “0” and “1” of the qubit.

The C-13 qubit is written and read out via a nitrogen vacancy center

The information exchange between this qubit and the surroundings is done indirectly: the researchers grew the diamond in such a way that it contains a bit of nitrogen in addition to tiny traces of the C-13 isotope so that so industrial wireless  me nitro gen atoms are located near a C-13 atom. Moreover, one carbon atom is missing in the nitrogen atom’s direct vicinity. Physicists therefore call this a nitrogen-vacancy center, or N-V center for short. The N-V center also has a spin and thus forms a qubit. The latter can easily be put into a defined quantum mechanical state with the aid of microwave and laser pulses. Furthermore, the information that it carries can be easily read out with a laser beam.

“It is easy to talk to the N-V center, so to speak, and it therefore serves as an auxiliary qubit,” says Hunger. The N-V center in turn talks to the nuclear spin of the carbon atom, as the two tiny bar magnets exert an influence on each other. “The quantum state of the carbon nucleus can be indirectly controlled by laser and microwave pulses addressing the N-V center, and additional direct manipulation of the nuclear spin is possible via strong radio frequency pulses; the qubit can thereby be read in. Similarly, it can also be read out via the N-V center.

The researchers selected the carbon atom rather than the N-V center as the actual memory location because its atomic nucleus has a comparatively small magnetic moment and thus reacts less sensitively than the N-V center to environmental influences. C-13 nuclei can therefore potentially store quantum information for a longer time, and are considered to be ideal systems for the storage of quantum information.

Two perturbing influences on the quantum memory must be suppressed

However, one problem is that the coupling to the N-V center, which is useful for writing and reading out, simultaneously causes the qubit in the C-13 atomic nucleus to lose its inf DIN-Rail router  ormation within only a few thousandths of a second. This is because, after the information is read in, the magnetic moment of the N-V center, which is left to its own devices, jumps to and fro uncontrollably and thereby perturbs the adjacent C-13 qubit, just as a bar magnet constantly turning to and fro induces a similar rocking motion in a neighboring, much weaker magnet. The magnetic moments of further C-13 nuclei in the diamond crystal influence the magnetic moment of the C-13 qubit in a similar way.

The effects of these two perturbations can be significantly reduced, however, as the researchers have proved. They suppressed the effect of the N-V center with a green laser beam. This forces the N-V center into one of the two magnetic states and prevents the natural fluctuation of the magnetic moment. In the process, the laser temporarily knocks an electron out of the N-V center, which captures it again shortly afterwards. The center is therefore being constantly ionized and immediately deionized again. This is again associated with the magnetic moment jumping to and fro.

By increasing the laser power to ten milliwatts, the physicists ensured that the magnetic moment changes its orientation much faster than in the original fluctuation. The qubit in the C-13 atomic nucleus therefore no longer experiences different magnetic fields, but rather an average value that is constant in time. This means the fluctuation is switched off. Staying with the bar magnet image: if one bar magnet is turned to and fro much faster than the other one can flip over, it simply remains in its orientation. This method increased the qubit’s lifetime to around half a second.

The lifetime of the qubit can theoretically be increased to 36 hours

The scientists used two tricks to minimize the interfering effect of the other C-13 atoms. First, they limited the percentage of the C-13 carbon isotope in their artificial diamond to one hundredth of a percent, whereas natural diamonds contain around one percent of the heavier carbon version. The next magnetic C-13 nuclei in the artificial diamond are therefore farther away from each other than in a natural diamond and correspondingly interfere less with each other. The second trick consisted in neutralizing the effects of the remaining C-13 nuclei on the qubit with the aid of cleverly chosen radio frequency pulses. Both methods increased the lifetime of the qubit to around 1.4 seconds.

“The theory says that the lifetime of the qubit can be increased to a maximum of 36 hours,” says David Hunger. “In principle, the current limitations can be pushed back further by improving the technology.” For example, by increasing the power of the green laser, although this would make it necessary to cool the diamond. Moreover, better optimized sequences of the control pulses and a further reduction in the C-13 concentration could increase the lifetime. Challenges that the research team will take on these, according to the physicist.

In addition to quantum memories for credit cards or passports, the researchers envisage that quantum memories could be important in future communication networks based on quantum information. Such a network would be needed for the exchange of information between quantum computers, for example. “The quantum information needs to be stored temporarily on longer paths through such networks,” says Hunger. Diamond crystals, such as the one used in this investigation, could be used for these so-called repeaters. Hunger acknowledges, however, that the miniaturization of the laser, microwave and radio frequency sources would have to progress significantly to enable applications such as the secure credit card. The read-out technology would also have to become more efficient. But this is only a question of time.

Image: iStockphoto; Max Planck Institute

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Image shows directly measured polaritons propagating through a flake of Hexagonal boron nitride (hBN). This material has been idePower Fault Detectionntified as an ideal substrate for two-dimensional materials research while also recently being demonstrated as an exciting optical material for infrared nanophotonics. Credit: US Naval Research Laboratory

A team of physicists, headed by the U.S. Naval Research Laboratory (NRL), have demonstrated the means to improve the optical loss characteristics and transmission efficiency of hexagonal boron nitride devices, enabling very small lasers and nanoscale optics.

“The applications for this research are considerably broad,” said Dr. Alexander J. Giles, research physicist, NRL Electronics Science and Technology Division. “By confining light to very small dimensions, nanophotonic devices have direct applications for use in ultra-high resolution microscopes, solar energy harvesting, optical computing and targeted medical therapies.”

Hexagonal boron nitride (hBN) forms an atomically thin lattice consisting of boron and nitrogen atoms. This material has recently been demonstrated as an exciting optical material for infrared nanophotonics and is considered an ‘ideal substrate’ for two-dimensional materials.

While previous work demonstrated that natural hBN supports deeply sub-diffractional hyperbolic phonon polaritons desired for applications, such as, sub-diffractional optical imaging (so-called ‘hyperlensing’), energy conversion, chemical sensing, and quantum nanophotonics, limited transmission efficiencies continue to persist.

“We have demonstrated that the inherent efficiency limitations of nanophotonics can be overcome throug Dual SIM M2M router  h the careful engineering of isotopes in polar semiconductors and dielectric materials,” Giles said.

Naturally occurring boron is comprised of two isotopes, boron-10 and boron-11, lending a 10 percent difference in atomic masses. This difference results in substantial losses due to phonon scattering, limiting the potential applications of this material. The research team at NRL has engineered greater than 99 percent isotopically pure samples of hBN, meaning they consist almost entirely of either boron-10 or boron-11 isotopes.

This approach results in a dramatic reduction in optical losses, resulting in optical modes that travel up to three times farther and persist for up to three times longer than natural hBN. These long-lived vibrational modes not only enable immediate advances specific to hBN – near field optics and chemical sensing – but also provide a strategic approach for other materials systems to exploit and build upon.

“Controlling and manipulating light at nanoscale, sub-diffractional dimensions is notoriously difficult and inefficient,” s Vending Telemeter  aid Giles. “Our work represents a new path forward for the next generation of materials and devices.”

Publication: Alexander J. Giles, et al., “Ultralow-loss polaritons in isotopically pure boron nitride,” Nature Materials, 2018; doi:10.1038/nmat5047