Detectarea și localizarea semnalelor ascunse și a interferențelor în operațiile militare;progresele înregistrate în domeniul optic pentru câmpul de luptă al secolului XXI;Dezvoltarea de antene purtabile pentru aplicații militare
senzori si resurse imbunatatite pentru tehnologiile cuantice.
Diamantele sunt fabricate din atomi de carbon într-o structură cristalină, dar dacă un atom de carbon este înlocuit cu un alt tip de atom, acest lucru va duce la un defect de zăbrele. Un astfel de defect este Nitrogen-Vacancy (NV), unde un atom de carbon este înlocuit cu un atom de azot, iar vecinul său lipsește (un spațiu gol rămâne în locul său).
Dacă acest defect este iluminat cu un laser verde, în urma răspunsului acesta va emite lumină roșie (fluorescentă) cu o caracteristică interesantă: intensitatea sa variază în funcție de proprietățile magnetice din mediul înconjurător. Această caracteristică unică face ca centrul NV să fie deosebit de util pentru măsurarea câmpurilor magnetice, a imaginilor magnetice (MRI), a calculului cuantic și a informațiilor.
| Posted: Nov 22, 2017 | |
Enhancing the quantum sensing capabilities of diamond(Nanowerk News) Researchers have discovered that dense ensembles of quantum spins can be created in diamond with high resolution using an electron microscopes, paving the way for enhanced sensors and resources for quantum technologies. |
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| Diamonds are made of carbon atoms in a crystalline structure, but if a carbon atom is replaced with another type of atom, this will result in a lattice defect. One such defect is the Nitrogen-Vacancy (NV), where one carbon atom is replaced by a nitrogen atom, and its neighbor is missing (an empty space remains in its place). | |
| If this defect is illuminated with a green laser, in response it will emit red light (fluoresce) with an interesting feature: its intensity varies depending on the magnetic properties in the environment. This unique feature makes the NV center particularly useful for measuring magnetic fields, magnetic imaging (MRI), and quantum computing and information. | |
| In order to produce optimal magnetic detectors, the density of these defects should be increased without increasing environmental noise and damaging the diamond properties. | |
| Now, scientists from the research group of Nir Bar-Gill at the Hebrew University of Jerusalem’s Racah Institute of Physics and Department of Applied Physics, in cooperation with Prof. Eyal Buks of the Technion – Israel Institute of Technology, have shown that ultra-high densities of NV centers can be obtained by a simple process of using electron beams to kick carbon atoms out of the lattice. | |
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| This photo shows a diamond sample illuminated by green light in home-built microscope. The sample is placed on a special mount, within a printed circuit board, used to deliver microwaves which allow quantum manipulations and magnetic sensing with the NVs. (Image: Yoav Romach | |
| This work, published in the scientific journal Applied Physics Letters („Enhanced concentrations of nitrogen-vacancy centers in diamond through TEM irradiation”), is a continuation of previous work in the field, and demonstrates an improvement in the densities of NV centers in a variety of diamond types. The irradiation is performed using an electron beam microscope (Transmission Electron Microscope or TEM), which has been specifically converted for this purpose. The availability of this device in nanotechnology centers in many universities in Israel and around the world enables this process with high spatial accuracy, quickly and simply. | |
| The enhanced densities of the NV color centers obtained, while maintaining their unique quantum properties, foreshadow future improvements in the sensitivity of diamond magnetic measurements, as well as promising directions in the study of solid state physics and quantum information theory. | |
| Nitrogen Vacancy (NV) color centers exhibit remarkable and unique properties, including long coherence times at room temperature (~ ms), optical initialization and readout, and coherent microwave control. | |
| „This work is an important stepping stone toward utilizing NV centers in diamond as resources for quantum technologies, such as enhanced sensing, quantum simulation and potentially quantum information processing”, said Bar-Gill, an Assistant Professor in the Dept. of Applied Physics and Racah Institute of Physics at the Hebrew University, where he founded the Quantum Information, Simulation and Sensing lab. | |
| „What is special about our approach is that it’s very simple and straightforward,” said Hebrew University researcher Dima Farfurnik. „You get sufficiently high NV concentrations that are appropriate for many applications with a simple procedure that can be done in-house.” |
| Source: The Hebrew University of Jerusalem |
Detectorul are caracteristici unice. La temperatura camerei, detectează semnale în intervalul de frecvență de la 330 la 500 gigahertzi. Este translucid și flexibil și se deschide la o varietate de aplicații. Tehnica poate fi utilizată pentru imagistică în zona terahertz (camera THz), dar și pentru identificarea diferitelor substanțe (senzor). De asemenea, poate avea un beneficiu potențial în îngrijirea sănătății, unde undele terahertz pot fi folosite pentru detectarea cancerului. Alte domenii în care detectorul poate fi utilizat sunt senzori de imagine pentru vehicule sau pentru comunicații fără fir.
Caracteristicile electronice unice ale grafenului, combinate cu natura sa flexibilă, fac din el un material promițător de integrare în plastic și țesătură, ceea ce va constitui un bloc de construcție important într-o lume viitoare interconectată. Tehnologia Graphene permite aplicații noi, printre altele, obiecte de zi cu zi, care sunt denumite în mod obișnuit Internetul Lucrurilor.
Detectorul arată posibilitățile concrete ale grafenului, un material care conduce extrem de bine curentul electric. Este o caracteristică care face ca grafenul să devină un bloc de atracție în domeniul electronicii rapide. Activitatea cercetătorilor de la Chalmers este, prin urmare, un important pas înainte pentru grafen în zona terahertz și un progres pentru performanțe ridicate și tehnologie ieftină terahertz
| Posted: Oct 31, 2017 | |
Graphene enables high-speed electronics on flexible materials(Nanowerk News) A flexible detector for terahertz frequencies (1000 gigahertz) has been developed by Chalmers researchers using graphene transistors on plastic substrates. It is the first of its kind, and can extend the use of terahertz technology to applications that will require flexible electronics, such as wireless sensor networks and wearable technology. The results are published in the scientific journal Applied Physics Letters („A flexible graphene terahertz detector”). |
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| With the help of the two-dimensional material graphene, the first flexible terahertz detector has been developed by researchers at Chalmers. The opportunities are great within health and Internet of Things, and for new types of sensors. (Image: Boid – Product Design Studio, Gothenburg) | |
| Terahertz radiation has a wide range of uses and can occur in everything from radio astronomy to medicine. The term refers to the electromagnetic waves whose frequencies range from 100 gigahertz to 10 terahertz. Demand for higher bandwidth in wireless communications and depiction for security applications has led to intensified research on systems and components intended for terahertz frequencies. | |
| One challenge has long been to enable low weight and cheap applications. However, advances in polymer technology have promoted the development of flexible electronics and enabled the production of high frequency units on flexible substrates. | |
| Now, Chalmers researchers Xinxin Yang, Andrei Vorobiev, Andrey Generalov, Michael A. Andersson and Jan Stake have developed the first mechanically flexible and graphene-based terahertz detector in its kind. Thus, paving the way for flexible terahertz electronics. | |
| The detector has unique features. At room temperature, it detects signals in the frequency range 330 to 500 gigahertz. It is translucent and flexible, and opens to a variety of applications. The technique can be used for imaging in the terahertz area (THz camera), but also for identifying different substances (sensor). It may also be of potential benefit in health care, where terahertz waves can be used to detect cancer. Other areas where the detector could be used are imaging sensors for vehicles or for wireless communications. | |
| The unique electronic features of graphene, combined with its flexible nature, make it a promising material to integrate into plastic and fabric, something that will be important building blocks in a future interconnected world. Graphene electronics enables new applications for, among other things, everyday objects, which are commonly referred to as the Internet of Things. | |
| The detector shows the concrete possibilities of graphene, a material that conduct electric current extremely well. It is a feature that makes graphene an attractive building block in fast electronics. The Chalmers researchers’ work is therefore an important step forward for graphene in the terahertz area, and a breakthrough for high performance and cheap flexible terahertz technology. | |
| The detector drew attention at the EU Tallinn Digital Summit recently, where several important technological innovations made possible by graphene and related materials were on display. At the summit, EU Heads of State and Government gathered to discuss digital innovation and Europe’s digital future. The flagship focus was to show what role graphene can play. | |
| The research is also part of Xinxin Yang’s licentiate seminar, which will be presented at Chalmers on 22 November 2017. |
| Source: Chalmers University of Technology |
Simulările sugerează că laserul SPP ar putea deveni un detector și mai sensibil pentru materialele biologice, chimice și de mediu decât utilizarea doar a cavității rezonante. Designul laserului permite, de asemenea, integrarea ușoară într-un circuit fotonic și poate permite, de asemenea, noi studii ale plasmonicii cuantice, interacțiunea nanometrică a materiei cu proprietățile cuantice ale luminii.
| Posted: Oct 13, 2017 | |
Plasmons in an open box create miniature laser(Nanowerk News) Scientists at the National Institute of Standards and Technology (NIST) have developed the first miniature laser in which the light is guided along the floor of an open metallic trench. The laser could act as a nanoscale device to sense minute amounts of pollutants and other chemicals in the environment, or detect the surface binding of biomolecules for medical diagnostics. |
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| Wenqi Zhu of NIST and the University of Maryland, along with NIST physicists Henri Lezec and Amit Agrawal, described their work (link is external) in a recent edition of Science Advances(„Surface-Plasmon-Polariton Laser based on a Metallic Trench Fabry-Perot Resonator”). The work was performed in collaboration with Nanjing University in China and the University of Michigan. | |
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| Illustration depicts cavity and sidewalls, made of silver, that form the miniature laser fabricated by scientists working at NIST. The cavity’s ultrathin coating (flat red layer) is the amplifying layer used to induce SPP lasing under illumination from above (blue-green light beam); a small amount of the red laser light leaks through a nanoscale notch positioned just below the cavity’s floor enabling researchers to monitor small wavelength shifts induced by the presence of the molecules on the cavity floor. (Image: NIST) | |
| The development of the new laser relies on the interaction between photons—particles of light—and the sea of electrons that floats along the surface of a metal. Interactions between the photons and ripples in the electron sea yield a special type of light wave, dubbed a surface plasmon polariton (SPP), which is tightly confined to travel only along the metal’s surface. This confinement makes the SPPs highly sensitive to anything lying on the metal surface. | |
| As a first step toward building the miniature laser, the team fashioned out of silver a small trench-shaped open cavity in which SPPs can resonate. The cavity is a flat surface flanked by tiny, mirror-like sidewalls that reflect the surface waves back and forth. | |
| Through careful fabrication, the resonant cavity possessed two key properties: all of its interior surfaces were smooth on an atomic scale, varying in thickness by no more than a few nanometers, and its sidewalls were perpendicular with respect to the flat cavity floor. The design, made possible by molding silver using a precisely patterned silicon template, enabled the SPPs to bounce back and forth across the cavity hundreds of times without losing significant energy, like a guitar string sustaining a pure note for a long time. That property, known as high quality factor, or high Q, is essential for constructing a laser. The Q measured by the team is the highest to date for any visible-light resonator using only SPPs. | |
| The high Q also enabled the cavity to act as an extremely selective filter for SPPs—only those with wavelengths that fell within a narrow band could resonate in the cavity. The narrow range is important because it enables the resonant cavity (even before it became part of a laser) to become a highly sensitive detector of tiny changes in its environment—the presence of particulate matter or the addition of a thin film to the cavity’s floor. Such changes shift the center of the band of wavelengths that will resonate in the cavity. | |
| “By achieving a narrow resonance, the shift in wavelength is clear, and the open cavity can act as an exquisitely sensitive detector,” said Lezec. | |
| After demonstrating that the cavity could be used as a sensor, the team then worked to turn their design into a laser. They did so by adding an ultrathin coating to the cavity that amplified the intensity of the SPP traveling through the structure. This is the first nanoscale laser ever constructed by manipulating an SPP traveling on a single flat metal surface, Lezec noted. | |
| Simulations suggest the SPP laser could become an even more sensitive detector for biological, chemical and environmental materials than using just the resonant cavity. The design of the laser also enables it to be easily integrated into a photonic circuit and may also enable new studies of quantum plasmonics, the nanoscale interaction of matter with the quantum properties of light. |
| Source: NIST |
Anchetatorii speră că o gamă mai largă le va permite să dezvolte, în colaborare cu unitatea SLAC a Departamentului de Energie de la Stanford, un spectrometru unic capabil să colecteze simultan și să măsoare cu precizie multe raze X de înaltă energie din materialele studiate la X Laser cu laser liber. Razele de raze penetrante de la această unealtă puternică sunt utilizate din ce în ce mai mult pentru a înțelege proprietățile materiei în timpuri foarte scurte, dar sunt necesare magistrale mai mari chiar și pentru această sursă strălucitoare de raze X.Versiunile noului instrument pot detecta semnale pe o gamă largă de frecvențe, de la gamma sau raze X la lungimi de undă la lungimi de undă cu lungimi de undă. Detectarea razei gama este crucială pentru contabilitatea materialelor nucleare, în special pentru urmărirea izotopilor de plutoniu în combustibilii nucleari uzați. Deoarece plutonul poate fi folosit pentru a crea arme nucleare, este important să existe metode rapide și exacte pentru a măsura cantitatea de plutoniu din combustibilul nuclear trimis pentru reprocesare.
| Posted: Aug 14, 2017 | |
New SQUID-based detector opens up new fields of study with new level of sensitivity(Nanowerk News) Investigators at the University of Colorado, Boulder and the National Institute of Standards and Technology (NIST) have developed a new sensor array-based instrument that offers ultra-low noise detection of small amounts of energy for a number of applications. The new device allows for the collection of data from many more detectors than was previously possible. |
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| The advance, reported in this week’s issue of Applied Physics Letters („Simultaneous readout of 128 X-ray and gamma-ray transition-edge microcalorimeters using microwave SQUID multiplexing”), is expected to allow applications in fields as diverse as nuclear materials accounting, astrophysics and X-ray spectrometry. | |
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| Photograph of a 33-channel SQUID multiplexer chip (20 mm x 4 mm) along with its microwave response showing the associated resonances. Multiple chips are daisy-chained together to achieve larger multiplexing factors. (Image: J.A.B. Mates, University of Colorado Boulder) (click on image to enlarge) | |
| The instrument consists of 128 superconducting sensors and combines their output into a single channel provided by a pair of coaxial cables. In the past, array size was limited by the bandwidth available to combine signals into a reasonable number of output channels. This new research demonstrates a hundred-fold bandwidth improvement, and the investigators plan to do even better soon. They overcame the bandwidth barrier by using very cold superconducting microwave circuitry and superconducting quantum interference device amplifiers, known as SQUIDs, capable of boosting the intensity of small signals. | |
| The new device uses radiofrequency SQUIDs to regulate high-quality microwave resonators. When these resonators are coupled to a common microwave feed line, with each resonator tuned to a different frequency, all sensors can be simultaneously monitored. | |
| “It’s as if one were trying to listen to hundreds of radio stations at one time, through one radio receiver,” said Ben Mates of the University of Colorado and lead author of the work. The SQUID resonators boost the signal in each channel, he explained, allowing simultaneous readout of all the radio stations at once. | |
| Versions of the new instrument can detect signals over a wide range of frequencies, from short-wavelength gamma or X-rays to long-wavelength microwaves. Gamma ray detection is crucial for nuclear materials accounting, particularly for tracking plutonium isotopes in spent nuclear fuels. Since plutonium can be used to create nuclear weapons, it is important to have fast, accurate methods to measure the amount of plutonium in nuclear fuel sent for reprocessing. | |
| Current technology for tracking plutonium uses mass spectrometry, but this method is expensive and time consuming. Faster and less costly technologies based on gamma-ray spectroscopy don’t have the accuracy to rule out small discrepancies in amounts of plutonium from a large facility. Only 8-10 kilograms of missing material is needed to build a nuclear bomb. The new array detectors are candidates to improve the accuracy of gamma-ray spectroscopy so that nuclear material can be tracked more easily. | |
| At the other end of the spectrum, the new instrument is expected to improve astronomical studies of cosmic microwave background radiation, which is mostly uniform, although small and important fluctuations exist in its intensity and polarization. The researchers predict that similar versions of their instrument will be used to search for fluctuations in polarization that are a signature of an inflationary epoch in the earliest moments of the universe. | |
| The investigators hope that a larger array will allow them to develop, in collaboration with the Department of Energy’s SLAC facility at Stanford, a unique spectrometer capable of simultaneously collecting and precisely measuring many high energy X-rays from materials under study at the California facility’s X-ray free electron laser. Penetrating X-rays from this powerful tool are increasingly used to understand the properties of matter on ultrashort timescales, but larger detector arrays are desirable even for this bright X-ray source. Toward this end, future work will focus on increasing the array size to a thousand sensors or more. |
| Source: American Institute of Physics |
Read more: New SQUID-based detector opens up new fields of study with new level of sensitivity
dispozitivele care pot detecta rapid chimic-biologic-exploziv (CBE)
au descoperit că forma bi-dimensională a carbonului, cunoscută sub numele de grafen, ar putea fi materialul ideal pentru fabricarea dispozitivelor plasmonice capabile să detecteze materiale explozive, substanțe chimice toxice alți compuși organici bazați pe o singură moleculă, afirmă un articol publicat în Physical Review B ( „Descrierea de sine strictă a amplificatorului cuantic al grafeinei” ).Dispozitivul de spargere de grafen poate fi utilizat pentru a proiecta dispozitive compacte de măsurare spectrală capabile să detecteze chiar și o singură moleculă dintr-o substanță, care este esențială pentru multe aplicații potențiale. Astfel de senzori ar putea detecta moleculele organice pe baza tranzițiilor lor vibraționale caracteristice („amprentele digitale”), deoarece lumina emisă / absorbită cade în regiunea infraroșie medie, care este exact în cazul în care funcționează spaserul bazat pe grafeni
| Posted: Aug 15, 2016 | |
‘Sniffer plasmons’ could detect a single molecule of explosives(Nanowerk News) Physicists from the Moscow Institute of Physics and Technology (MIPT) have found that the two-dimensional form of carbon, known as graphene, might be the ideal material for manufacturing plasmonic devices capable of detecting explosive materials, toxic chemicals, and other organic compounds based on a single molecule, says an article published in Physical Review B („Self-consistent description of graphene quantum amplifier”). |
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| Design of the spaser with the graphene layer shown as a honeycomb lattice above the dielectric layer (blue). The spaser is optically pumped through the active (gain) medium shown in orange. | |
| Plasmons in constructing high-accuracy electronics and optics | |
| Scientists have long been fascinated by the potential applications of a quasiparticle called the plasmon, a quantum of plasma oscillations. In the case of a solid body, plasmons are the oscillations of free electrons. Of special interest are the effects arising from the surface interactions of electromagnetic waves with plasmons—usually in the context of metals or semimetals, as they have a higher free electron density. Harnessing these effects could bring about a breakthrough in high-accuracy electronics and optics. One possibility opened up by plasmonic effects is the subwavelength light focusing, which increases the sensitivity of plasmonic devices to a point where they can distinguish a single molecule. Such measurements are beyond what any conventional (classical) optical devices can achieve. Unfortunately, plasmons in metals tend to lose energy quickly due to resistance, and for this reason they are not self-sustained, i.e. they need continuous excitation. Scientists are trying to tackle this issue by using composite materials with predefined microstructure, including graphene. | |
| Graphene is an allotrope of carbon in the form of a two-dimensional crystal. It can be visualised as a one-atom-thick honeycomb lattice made of carbon atoms. Two MIPT graduates, Andre Geim and Konstantin Novoselov, were the first to isolate graphene, which won them a Nobel Prize in Physics. Graphene is a semiconductor with extremely high charge carrier mobility. Its electrical conductivity is also exceptionally high, which makes graphene-based transistors possible. | |
| Theoretical physicists give the okay | |
| Although, plasmonic devices have seemed an exciting prospect to pursue from the start, to take advantage of them, it was first necessary to find out whether the technology behind them was feasible. To do this, scientists had to find a numerical solution to the relevant quantum-mechanical equations. This was accomplished by a team of researchers at the Laboratory of Nanostructure Spectroscopy headed by Prof. Yurii Lozovik: they formulated and solved the necessary equation. Their research has led them to develop a quantum model that predicts plasmonic behaviour in graphene. As a result, the scientists described the operation of a surface-plasmon-emitting diode (SPED) and the nanoplasmonic counterpart of the laser—known as the spaser—whose construction involves a graphene layer. | |
| A spaser could be described as a device similar to a laser and operating on the same basic principle. However, to produce radiation, it relies on optical transitions in the gain medium, and the particles emitted are surface plasmons, as opposed to photons produced by a laser. An SPED is different from a spaser in that it is an incoherent source of surface plasmons. It also requires considerably lower pump power. Both devices would operate within the infrared region of the spectrum, which is useful for studying biological molecules. | |
| ‘The graphene spaser could be used to design compact spectral measurement devices capable of detecting even a single molecule of a substance, which is essential for many potential applications. Such sensors could detect organic molecules based on their characteristic vibrational transitions (‘fingerprints’), as the light emitted/absorbed falls into the medium infrared region, which is exactly where the graphene-based spaser operates,’ says Alexander Dorofeenko, one of the authors of the study. |
| Source: Moscow Institute of Physics and Technology |
Echipament ptr.detectare medicamente false, inclusiv droguri;microscop adaptabil la telefon mobil cu ajutorul caruia poti detecta medicamentele falsificate ;cititor de bare
detectare agenti chimici de lupta
Camerele portabile cu infraroșu care pot vedea lungimi de undă invizibile de lumină au fost utilizate de mult timp de către organele de drept, soldați, pompieri și alții pentru a vedea în întuneric sau pentru a localiza oamenii prin căldura corporală pe care o emită. Dar imaginile neclare pe care aceste dispozitive le produc nu sunt câteodată mai mult decât bloburi colorate indistincte.
Detectoarele cu infraroșu mai puternice care produc imagini mai detaliate – cele utilizate în mod obișnuit de către NASA și agențiile de apărare – sunt mari, costisitoare și pot funcționa doar la temperaturi extrem de scăzute.
| Posted: Jun 07, 2016 | |
$1.3 million DARPA grant to fund graphene infrared detector research(Nanowerk News) The Defense Advanced Research Projects Agency has awarded a $1.3 million grant to a team led by University of Central Florida researcher Debashis Chanda to fund the development of a next-generation infrared detector that could be used in fields as varied as night vision, meteorology and space exploration. |
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| „We are working on a novel infrared detection and imaging technology. The detection mechanism is very different than what is being used now,” said Chanda, an assistant professor with joint appointments to UCF’s NanoScience Technology Center and College of Optics & Photonics. | |
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| Dr. Debashis Chanda, University of Central Florida | |
| The work caught the attention of DARPA, which made news recently with fanciful technology like a crewless Navy drone ship, workhorse robots to lug soldiers’ heavy gear, and the XS-1 space plane. DARPA is funding the UCF team’s research for the 3½ years. | |
| Portable infrared cameras that can see invisible wavelengths of light have long been used by law enforcement, soldiers, firefighters and others to see in the dark or locate people by the body heat they emit. But the blurry images those devices produce are sometimes nothing more than indistinct colored blobs. | |
| More powerful infrared detectors that produce more detailed images – ones typically used by NASA and defense agencies – are large, expensive and can only function at ultra-low temperatures. | |
| „The biggest problem is that most infrared detectors need cryogenic cooling, and in most cases you can’t carry a big cooling tank with you,” Chanda said. „That is a big barrier.” | |
| Chanda and associate professor Michael Leuenberger of the NTC and UCF’s Department of Physics, are working on an entirely new type of detector that relies on a seemingly magic material. The team plans to use a substance known as graphene, that is so thin – just one atomic layer thick – it is a two-dimensional material. | |
| Chanda envisions an infrared detector that is small, portable, doesn’t need to be cooled and produces high-resolution images. Unlike current technologies, which can detect only one band of light, the next-gen detector would be tunable and able to see a range of bands. | |
| „We came up with the idea that one can make graphene to strongly absorb light in the infrared domain and we showed that we can also tune the response electronically,” Chanda said. „If you can take an infrared image in different spectral bands, you can extract much more information.” | |
| The team intends to collaborate with defense majors such as Northrop Grumman, Lockheed Martin and St. Johns Optical Systems for integration and packaging. |
| Source: University of Central Florida |
Read more: $1.3 million DARPA grant to fund graphene infrared detector research
Sistem de laser pentru detectia armelor chimice, explozibile , narcotice ,etc
