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Showing posts with label Nanotechnology. Show all posts
Showing posts with label Nanotechnology. Show all posts

Wednesday, 17 July 2019

Researchers have discovered that a bacterium can be used to produce graphene


The study of the exposure of graphite to a species of bacteria has shown that the latter is capable of converting this material into graphene. The industrial application of this discovery could provide substantial savings in the production of this material.


Produced and extracted for the first time only 15 years ago, graphene is a material consisting of a single layer of carbon, which is in nature the main component of graphite. It is particularly used for its very light weight and strength, as well as for its conductive properties in electronics. But it could have been used in more areas if its cost of production had not been a major drag (about 100 euros per gram).

Since 2004, scientists have been trying to develop new methods to make their production cheaper. The first method used was very rudimentary because it was sticking tape to the surface of the graphite to extract it. Chemical methods have then emerged, but the latest, explained in a paper published this month, uses biological processes and could significantly lower the cost of production.

Researchers from Delft University of Technology in the Netherlands and Rochester, New York, have shown that Shewanella oneidensis is capable of producing graphene when mixed with graphite oxide. and thanks to a reaction called in chemistry "reduction", where oxygen molecules are removed from the latter, leaving only conductive graphene. This natural method has the advantage of avoiding the use of chemicals currently used by industries, and is less expensive. Its development on a larger scale (than the laboratory) could allow its application in more computing or medical devices.

The production of a large quantity is difficult and usually gives thicker and less pure graphene. That's where our work comes in, "says Anne Meyer, a biologist at the University of Rochester.

Indeed, not only have the researchers discovered a new way to obtain the material, but the final product is also thinner, more stable, and has a better longevity than graphene chemically produced.

 The production of graphene by the bacterium also has the advantage of not removing all oxygen groups, which could be exploited for their properties to attach to certain molecules. This opens new paths in the design of biomedical devices such as field-effect transistor biosensors, which are devices that detect specific biological molecules, one of the best known being the glucose meter (measuring glucose levels in diabetics).

Many analyzes have yet to be done before considering the wider use of this technique, which could significantly reduce the price of many electronic devices. But given the quality of the graphene obtained and the absence of chemical compounds, the production of this material promises to increase in the future.

" Our graphene produced by bacteria will significantly improve the overall development of this product, " says Meyer.


Bibliography:

Creation of Conductive Graphene Materials by Bacterial Reduction Using Shewanella Oneidensis
Benjamin A. E. Lehner Vera A. E. C. Janssen Dr. Ewa M. Spiesz Dominik Benz Dr. Stan J. J. Brouns Dr. Anne S. Meyer Prof. Dr. Herre S. J. van der Zant
https://doi.org/10.1002/open.201900186

First real-time images of molecules that change their electric charge


Just like an atom, a molecule can lose or gain electrons , thus altering its overall electrical charge. These phenomena of modification of the electric charge play a crucial role in the transfer of molecular energy governing certain catalytic and biochemical processes. For the first time, chemists have been able to observe in real time the structural modification of molecules due to electric charge transitions. Results that should help to better understand various essential biological processes.


Using some of the most advanced microscopy technologies in the world, chemists have captured images of molecules that change their electrical charge in real time. To do this, they added and removed electrons , directly observing the changes in the structure of four molecules. The results were published in the journal Science.

Molecular changes in electrical charge have been known for a long time, but this is the first direct observation of the phenomenon. This could help us better understand several molecular processes, including chemical reactions, catalysis and charge transport, and even biological processes.

" We were able to solve the structural changes of individual molecules with unprecedented resolution, " says chemist Leo Gross of IBM Research-Zurich. " This new understanding unveils some of the mysteries of molecular charge-function relationships in how biology converts and transports energy ."

An atomic force microscope to observe molecular charge transitions

The team used atomic force microscopy. The laser tip scans the surface of the structures to be studied, detecting all structural changes, even the weakest ones. These are recorded to create an image of what the probe is scanning. In this way, scientists can get an image of the elements too small to be seen by optical means.

Thus, four types of molecules - azobenzene, pentacene, tetracyanoquinodimethane (TCNQ) and porphine - were examined under a microscope in a cold vacuum chamber to ensure that no external influence would alter the results. A single molecule was placed on a sodium chloride film, and then a small voltage was sent through the probe to transfer electrons to the molecule, one at a time.

The atomic force microscope allowed researchers to image the structure of four different molecules, depending on their state of charge. Credits: IBM


Gross and his colleagues had already developed this load control technique and described it in a study in 2015. They also described their imaging technique in 2009. In this new work, however, the team found a way to combine the two techniques to image the molecules and control the charge at the same time.

They imaged the four molecules in at least two of these four states: positive (minus one electron), neutral (the same number of protons and electrons), negative (plus one electron) and double negative (plus two electrons). The four molecules reacted differently to changes in charge.

This video shows how the porphine molecule transforms as it loses electrons under these controlled conditions:


Molecular charge transition and fundamental biological processes

The azobenzene molecule has become physically twisted. With pentacene, the areas of the molecule became more reactive because of the extra electrons. The change in charge resulted in a change in the type of bond between the TCNQ atoms, which moved physically on the film. And in the porphine, it was not only the type of links, but also their length that changed.

Atomic force microscopy images of each type of molecule, for four different states of electrical charge. Credits: Shadi Fatayer et al. 2019


These results will help to better understand the molecular energy transfer. Specifically, examining porphine molecules so closely may help us better understand some fundamental biological processes, because porphine is the parent compound of porphyrins, a group of organic compounds that make up both chlorophyll and hemoglobin.

" The charge transitions of these molecules are essential to life. Thanks to our new technique, we can better understand how the charge modifies the structure and function of molecules, which play an essential role in many ways, such as photoconversion and the transport of energy in living organisms "concludes Gross.



Bibliography:

Molecular structure elucidation with charge-state control
Shadi Fatayer1,*, Florian Albrecht1, Yunlong Zhang2, Darius Urbonas1, Diego Peña3, Nikolaj Moll1, Leo Gross1,*
Science 12 Jul 2019:
Vol. 365, Issue 6449, pp. 142-145
DOI: 10.1126/science.aax5895

Tuesday, 16 July 2019

Physicists reveal the very first image of quantum entanglement between two particles


Among the many phenomena arising from quantum mechanics, quantum entanglement is certainly one of the strangest. When two particles are entangled, they cease to be objects in their own right to become one and the same physical system of solidarity; any modification of one has instantaneous repercussions on the other, regardless of the distance that separates them. For the first time, researchers from the University of Glasgow provided the very first image of a pair of entangled photons, thus demonstrating the violation of Bell's inequalities.

This particular photo shows the entanglement between two photons - the boson of the electromagnetic interaction. Paul-Antoine Moreau, lead author of the study, states that the image is " an elegant demonstration of a fundamental property of nature ". The study was published in the journal Science Advances.

To capture this phenomenon, Moreau and a team of physicists have created a system that sends entangled photon fluxes on what they have described as "unconventional objects." The experiment consisted of capturing four photon images under four different phase transitions.

The researchers succeeded in imaging the entanglement of photon pairs crossing series of four-phase transitions. Credits: Paul-Antoine Moreau et al. 2019


It is actually a composite image of several images of photons that pass through a series of four-phase transitions. Basically, physicists have divided the entangled photons and sent a beam through a liquid crystal material known as barium β-borate, triggering four-phase transitions. At the same time, they captured photos of the entangled pair passing through the same phase transitions, even though it had not crossed the liquid crystal.

Scheme of experimental protocol used by researchers. The entangled photon beam is from the bottom left, half of the entangled pair splits to the left and passes through the four phase filters. The others that go straight have not gone through the filters, but have undergone the same phase changes. Credits: Paul-Antoine Moreau et al. 2019


The violation of Bell's inequalities in images

The camera was able to capture the images of these different sequences of events at the same time, showing that the two photons had changed in the same way despite their spatial remoteness.

Physicists first obtain a raw image from the four-phase filter (left). Then, thanks to a special treatment (de-scanning), they get a clearer picture of the entanglement, which confirms the violation of Bell's inequalities. Credits: Paul-Antoine Moreau et al. 2019

The physicist John Stewart Bell has defined a series of conditions called "Bell inequalities". The latter characterize relations that must be respected by measurements on entangled states, in the context of a local deterministic theory with hidden variables. Demonstrating the entanglement between two particles amounts to violating these inequalities.

" We report here an experiment demonstrating the violation of a Bell inequality in the observed images. This result paves the way for new quantum imaging schemes ... and suggests promising perspectives for quantum information schemes based on spatial variables "concludes the team.




Bibliography

Imaging Bell-type nonlocal behavior
Paul-Antoine Moreau*, Ermes Toninelli, Thomas Gregory, Reuben S. Aspden, Peter A. Morris and Miles J. Padgett*
Science Advances 12 Jul 2019:
Vol. 5, no. 7, eaaw2563
DOI: 10.1126/sciadv.aaw2563

Wednesday, 3 July 2019

Discovery. These quantum particles are basically "immortal"



In the late 1950s, the Soviet physicist Lev Landau developed the theory of Fermi liquids - the state of matter observed at low temperatures for crystalline solids - and introduced the concept of quasiparticles. The latter make it possible to describe complex physical systems in terms of particle groups and interactions, taking the form of vibrations and excitations. Recently, physicists have discovered that unlike ordinary particles that eventually disintegrate and disappear, quasiparticles can escape this inexorable fate, becoming "immortal".


The second law of thermodynamics is clear: the Universe systematically evolves towards disorder, entropy being brought to continually grow in any isolated system. Disintegrated objects can not reform. However, quantum mechanics is known to contravene certain well-established physical rules. In an article published in the journal Nature Physics , physicists have shown that quasiparticles that disintegrate can "be reborn from their ashes".

" Until now, the hypothesis was that the quasiparticles of interacting quantum systems decay after a while, " says physicist Frank Pollman of Munich Technical University. " We now know that the opposite is happening: strong interactions can even completely stop disintegration ." 


Three examples of quasiparticles: a) A polaron, that is to say an electron in a solid interacting with the crystal lattice; b) an exciton, that is, an electron-hole bound state; c) An angulon, that is to say a quantum rotor formed by a phonon field. Credits: Mikhail Lemeshko

Quasiparticles are not ordinary particles, like electrons and quarks. Rather, it is the disturbances or excitations in a solid caused by electrical or magnetic forces that collectively behave like particles. Phonons - discrete units of vibratory energy in a crystal lattice, for example - are classified as quasi-particles, as are polarons, electrons trapped in a network surrounded by a polarization cloud.

Quasiparticles: they disintegrate ... then reform

The researchers involved in this latest study have developed numerical methods to compute the complex interactions of these quasiparticles and have run simulations on a powerful computer to observe their disintegration.

" The result of the simulation: of course, the quasiparticles disintegrate, but new entities of identical particles emerge from the debris, " says physicist Ruben Verresen from the Technical University of Munich and the Max Planck Institute for Complex Systems Physics . " If this degradation occurs very quickly, a reverse reaction will occur after a while and debris will converge again. This process can be repeated at infinity and a sustained oscillation between disintegration and rebirth appears.

This does not violate the second law of thermodynamics because oscillation is a wave transformed into matter, which is covered by the concept of quantum mechanics of the wave-particle duality. Their entropy does not decrease but remains constant. In fact, the discovery solved two other puzzles. For example, there is a magnetic compound, Ba3CoSb2O9, used in experiments whose unexpected stability had previously been found.

It now seems that the key lies in the quasi-magnetic particles it contains, called magnons. According to the simulation, they reorganize after the degradation. Helium is another potential example: it becomes a superfluid without resistance at a temperature close to absolute zero, and this particular property could be explained by the fact that this gas is filled with quasi-particles called rotons.

For the moment, the work only concerns theory, but researchers believe that this immortality of quasi-particles offers a strong potential for sustainable data storage in quantum computing systems.


Bibliography:

 Avoided quasiparticle decay from strong quantum interactions
Ruben Verresen, Roderich Moessner, Frank Pollmann
 Nature Physics 
DOI: 10.1038 / s41567-019-0535-3

Monday, 24 June 2019

Researchers break quantum limit in precision of force and position measurements

The technique is unprecedented, but very simple, which will facilitate its practical use in other experiments and laboratories. [Image: Mason et al. - 10.1038 / s41567-019-0533-5]

Precision limit

The precision of the force and position measurements has been raised to a new level thanks to a collaboration of researchers from the University of Copenhagen and the Niels Bohr Institute in Denmark.

The experiment is the first to overcome the so-called "Standard Quantum Limit", or SQL ( Standard Quantum Limit ), which imposes itself as a barrier in the most common and most successful optical techniques for ultra-precise position measurements.

In 2014, a US team detected the smallest force already measured , coming very close to SQL, but did not win. In fact, physicists and engineers have been trying to overcome the Quantum Limit for more than 50 years, using a variety of techniques - but unsuccessfully so far.

David Mason and his colleagues broke the barrier by making a simple modification to the most commonly used approach, which allowed them to cancel the quantum noise in the measurement well enough to push the limit.

The result - and the experiment itself - has important implications for gravitational wave astronomy techniques, atomic force microscopy, various nanotechnology techniques, and the entire field of quantum sensors that have detonated the boundaries of precision in several areas.

Uncertainty and inaccuracy

Quantum actions have quantum consequences. In the context of measurements, this usually means that the very act of measuring a system disturbs you. This effect is called reverse action, or feedback ( backaction ), and is a consequence of the fundamental uncertainties of the systems at the atomic scale, encompassed by the uncertainty principle of Heisenberg .

In many cases, this uncertainty sets a limit to the accuracy with which a measure can be obtained because, in addition to a certain number of figures after the comma, everything is uncertain.

Gravitational wave telescopes, such as LIGO and Virgo, reflect the laser light in a mirror to measure their position in an optical configuration known as an interferometer. The imprecision of this measurement can be improved by increasing the laser power, but eventually the random reflections of the laser photons will disturb the position of the mirror, leading to a less sensitive measurement that will leave astronomical objects weak or distant outside the field of detection.

The Standard Quantum Limit (SQL) is established when an optimal balance between the feedback and the noise responsible for imprecision is achieved. This minimum noise level defines, for example, the best possible accuracy obtained by any interferometer.


A thin silicon nitride membrane (white) is stretched along a silicon (blue) frame. The membrane contains a pattern of holes, with a small island in the center, whose vibrations were measured in the experiment. [Image: Niels Bohr Institute]

Overcoming the Standard Quantum Limit

Mason and his colleagues were able to break the SQL through an ingenious combination of optical and nanomechanical techniques, allowing you to perform the first measurement of an object's position with a precision that exceeds the limit.

Like the LIGO, the new approach uses a laser interferometer to measure a position, in this case the position of a membrane made of ceramic silicon nitride. Although very thin (20 nanometers), the membrane is several millimeters wide and is easily visible to the naked eye.

The trick to going beyond SQL involves doing a double measurement of the light reflected by the membrane. In this configuration, the detector is capable of simultaneously measuring inaccuracy and feedback in a manner that allows those noise sources to mutually cancel each other. In other words, what remains is a "clean" measure.

Using this technique, team measured the position of their membrane with almost 30% better precision than the "allowed" by SQL.

"We are using quantum effects that emerge in the measurement setup itself, so the extra technological effort is really very small. That's good news for possible practical applications," Mason said.



Bibliography:

 Continuous force and displacement measurement below the standard quantum limit
David Mason, Junxin Chen, Massimiliano Rossi, Yeghishe Tsaturyan, Albert Schliesser
Nature Physics
DOI: 10.1038 / s41567-019-0533-5

Sunday, 23 June 2019

Physicists discover exotic spiraling electrons

The two types of "chiral surface excitons" are on the right and left sides of the image. They are generated by polarized light to the right and left (photons in blue). Excitons consist of an electron (light blue) orbiting a gap (black) in the same orientation of light. The electron and the gap are annihilated in less than a trillionth of a second, emitting light (photons in green) that can be harnessed for illumination, solar cells, lasers and screens [Hsiang-Hsi Kung / Rutgers]

Surface chiral exciton

Physicists have discovered an exotic form of electron that can lead to advances in lighting, solar cells, lasers and electronic screens.

Spinning like planets, these electrons consist of particles and "antiparticles" orbiting around one another on the surface of solid materials - not antimatter, but particles with opposing charges.

These exotic particles - or quasiparticles - were termed "surface chiral excitons."

Excitons form when intense light strikes a solid, kicking electrons negatively charged from their positions and leaving behind positively charged gaps - ejected electrons form surface plasmons , another quasiparticle of great technological interest.

Chiral refers to entities, such as their right and left hands, which correspond, but are asymmetrical, and can not be superimposed on their mirror image. The chirality of the new quasiparticle depends on the polarization of the light that produces it.

The electrons and gaps generated in this process resemble fast spinning rods. Electrons (negative charges) eventually "spiral" into gaps (positive charges), annihilating each other in less than a trillionth of a second, which results in the emission of a type of light called photoluminescence .

Photoluminescence is involved in numerous technological applications, such as solar cells, lasers, LEDs, screens, etc. Thus, the controlled production of light by the production of surface chiral excitons may eventually be exploited in all such devices.

Bismuth selenide

Hsiang-Hsi Kung and his colleagues at Rutgers University in the United States have discovered the chiral excitons on the surface of a crystal called bismuth selenide, which can be produced on a large scale and used in coatings and other materials in electronics - all at room temperature.

This crystal had already been used to synthesize a bizarre substance that unifies spintronics and quantum computing . And, on its surface, was also discovered, in 2013, a then unprecedented coupling between photon and electron, uniting matter and energy .

"Bismuth selenide is a fascinating compound that belongs to a family of quantum materials called ' topological insulation .' They have several surface channels that are highly efficient in conducting electricity," said Professor Girsh Blumberg.

The dynamics of chiral excitons is still unclear and the team plans to use ultrafast images to study it in depth. They also evaluate that surface chiral excitons can be found in other materials.




Bibliography:

 Observation of chiral surface excitons in a topological insulator Bi2Se3
Hsiang-Hsi Kung, Adamya P. Goyal, Dmitrii L. Maslov, Xueyun Wang, Alexander Lee, Alexander F. Kemper, Sang-Wook Cheong, Girsh Blumberg
 Proceedings of the National Academy of Sciences
 DOI: 10.1073 / pnas.1813514116

Thursday, 20 June 2019

Two individual atoms are set to interact for the first time

As the two lasers move towards each other, the two atoms interact with each other and change their properties by reason of this approximation. [Image: University of Otago]

Interaction between individual atoms

You must have gotten tired of hearing about the nanotechnology dream of building things from the bottom up, building atoms and molecules one at a time. That was what Richard Feynman proposed in his famous lecture "There is a lot of space down there" in 1959.

Now maybe we have taken the final step that will allow this.

Although we are accustomed to chemical reactions in which the zillions of atoms of a substance react with the zillions of atoms of another substance, to pick up an atom and to position it carefully next to another and to see them influence each other is a much greater challenge .

For that was precisely what a team at the University of Otago in New Zealand managed to do.

They placed one atom in each of two laser beams and moved them toward each other. Because atoms are like magnets, when the pair began to interact, they began to change the direction of each other, counterbalancing each other.


Control the atomic world

This is the first time that this pure basic interaction test has been demonstrated in the laboratory using two individual atoms. Previous experiments have used multiple atoms, resulting in undesirable interactions, such as chemical reactions between them.

And it is also much more accurate than anything that had ever been done with the optical tweezers, which won the Nobel Prize in Physics last year.

"Our work represents an important step in our ability to control the atomic world," said Professor Mikkel Andersen, team coordinator.


Taming quantum entanglement

The team plans to take the next step by trying to put the two atoms in quantum entanglement, which means that both will be inextricably connected even after they are separated. Interlacing is one of the cornerstones of quantum computing .

"When we get to the point where we can explore quantum entanglement, we will have a second quantum technological revolution - as we did with lasers, which made the internet possible. That is why making entanglement technology robust is important," Andersen said.



Bibliography:

 Thermally robust spin correlations between two 85Rb atoms in an optical microtrap
 Pimonpan Sompet, Stuart S. Szigeti, Eyal Schwartz, Ashton S. Bradley, Mikkel F. Andersen
 Nature Communications
 Vol. 10, Article number: 1889
 DOI: 10.1038 / s41467 -019-09420-6

Thermomechanical micromachine detects T-rays


Rays:

The terahertz radiation (THz) is one of the most promising areas of current research, with applications ranging from healthcare to the ultra - efficient magnetic recording data.

These T-rays are not yet being used on a large scale because the sources for their emission and the antennas for their detection are still being improved.

Ya Zhang, from the University of Tokyo, has now made a remarkable breakthrough in this area.

It has developed a microelectromechanical device ( MEMS ) that detects terahertz radiation at room temperature, is easy to use, much faster than conventional thermal sensors, is highly sensitive and can be incorporated into detector arrays to increase efficiency.

The small terahertz antenna detects the T rays using the change in the mechanical resonance frequency of a tiny suspended beam, a change caused by thermal expansion generated by THz radiation. It operates at room temperature, while similar devices require cryogenic temperatures of up to -270 ° C.

This breakthrough can unleash a new era of terahertz technologies, such as sensors and cameras, including medical imaging - T-rays allow imaging of the interior of the human body without the use of ionizing radiation, such as X-rays.

Terahertz antenna

The MEMS (microelectromechanical system) consists of a small beam suspended over an opening. The beam is coated with a resistive metal film (NiCr - nickel - chromium) that has the ability to absorb THz radiation, which in turn transfers heat to the beam. This increase in temperature causes the beam to expand very slightly, which can be detected as a change in the frequency with which it vibrates.

This MEMS-based approach has a number of advantages over existing alternatives for detecting THz radiation. The ability to operate at room temperature without the need for cooling makes the sensor suitable for a variety of practical applications. It is also extremely sensitive by detecting radiation that causes changes in temperature to only one millionth of a degree centigrade and offering a reading 100 times faster than other prototypes.

"Another advantage of this system is that it can be produced using standard methods to make semiconductor devices, which will potentially allow them to be incorporated into mass-produced THz based cameras and sensors," said Ya Zhang. "We hope that our work will lead to an explosion of interest and more innovation in this field."


References:

 Fast and sensitive bolometric terahertz detection at room temperature through thermomechanical transduction

 Ya Zhang, Suguru Hosono, Naomi Nagai, Sang-Hun Song, Kazuhiko Hirakawa

 Journal of Applied Physics 
Vol. 125, Issue 15
 DOI: 10.1063 / 1.5045256

Wednesday, 19 June 2019

Chipscope, the microscope on a chip that can revolutionize medicine

Ultraminiaturized high resolution microscope scheme. [Image: Chipscope Project / Disclosure]

Microscope on a chip

Resolution obtained with conventional optical microscopes is limited because of physical laws. This means that they can not be used to directly observe isolated proteins, DNA molecules or inside living cells, which are smaller than the visible wavelength of light.

Today, it is only possible to do this through indirect observation, that is, with the interpretation of the data measured by electronic microscopes - which are complex, expensive and bulky.

It occurs that electronic microscopes are not suitable for the observation of delicate living tissue; in addition to complex preparations, the energy they use "fries" the samples.

To overcome these limitations, a group of researchers from several countries, funded by the European Union, is developing a microscope the size of a chip that uses light-emitting diode arrays (LEDs), with a diameter smaller than a human hair, to illuminate the object being observed.

The miniaturized microscope called "chipscópio" ( ChipScope ), combines simplicity, ease of operation, accessibility and clear, high resolution optics.

Schematic of the chipscope and photo of the prototype. [Image: Chipscope Project / Disclosure] 

Miniaturized Microscope

These future microscopes on a chip can also be integrated into consumer electronics just as cameras are embedded in mobile phones. The sample is placed on the LEDs and underneath a photodetector that picks up the light signals.

Unlike conventional microscopy, spatial resolution is provided by the LEDs, not by the optical detection system. Therefore, this system does not require specific alignments or complex focus systems.

The LEDs can be turned on and off individually at high speed, allowing cells to be observed in real time, capturing up to 10 frames per second.


This new miniaturized microscopy technology promises to give impetus to research in areas that currently use optical microscopes - particularly in medicine. It will also assist field researchers without access to laboratories or other scientific infrastructures.

The first version of the Chipscope microscope is ready and being tested by the team in the study of the development of idiopathic pulmonary fibrosis, a chronic age-related lung disease that kills 500,000 people worldwide each year.

Tuesday, 18 June 2019

Photonics mix light and matter - you can not tell what is what

Now it is light, now it is matter - as it is too fast to separate the "now", there remains a hybrid of matter and light. [Image: Denis Baranov / Yen Strandqvist / Chalmers University of Technology]

Mixture of light and matter

Researchers in Sweden have discovered a completely new way of capturing, amplifying and connecting light to matter at the nanoscopic level.

Using a tiny box, constructed of a material consisting of a single atomic layer, they were able to create a kind of feedback circuit in which light and matter became indistinguishable.

This innovative "box of light" causes the alternations between light and matter to occur so rapidly that it is no longer possible to distinguish between the two states. Light and matter become one.

"We have created a hybrid consisting of equal parts of light and matter. The concept opens up completely new doors in both fundamental and applied nanopotonics, and there is a great scientific interest in this," said Professor Ruggero Verre of the University of Technology. Chalmers.

Nanophotonics

The creation of this hybrid of light and matter was possible using two concepts already known, but combining them in an innovative way. The first is a nanoanthene, which captures and emits light in the most efficient way possible. The other is a kind of atomically thin two-dimensional material, known as "transition metal dicalcogeneto", or TMDC ( transition metal dichalcogenide ) - these materials are better known as molibdenite , but belong to this class both molybdenum disulphide (MoS2) as the tungsten disulfide (WS2) .

The team worked with a well-known TMDC, the tungsten disulfide, which resembles graphene but using it in a new way.

The superfluid light and some quasiparticles promise new ways of computing using light and matter . [Image: Polytechnique Montreal]

The trick has been to create a small resonance box, within which light and matter interact - it is very much like the case of a guitar, except that it operates with sonic waves. The resonance box ensures that the light is captured by the nanoparticles and reflected in a certain "pitch" within the material, thus ensuring that light energy can be efficiently transferred to the electrons of the TMDC material and re-emitted. It all occurs in a single particle with a diameter of only 100 nanometers, or 0.00001 centimeters.

"We've been able to demonstrate that materials in atomically thin layers can be nanostructured in tiny optical resonators, which is of great interest for photonic applications." As this is a new way of using the material, we are calling it 'TMDC nanopotonics'. that this field of research has a bright future, "said Professor Timur Shegai, team coordinator.

Photonics and nanophotonics

The photonics involves the various ways to use light. Fiber optic communication is an example of photonics, as is the technology behind photodetectors and solar cells. When the photonic components are so small that they are measured in nanometers, their use is called the nanophotonics.


Bibliography:

Transition metal dichalcogenide nanodisks as high-index dielectric Mie nanoresonators
Ruggero Verre, Denis G. Baranov, Battulga Munkhbat, Jorge Cuadra, Mikael Käll, Timur Shegai Nature Nanotechnology
DOI: 10.1038 / s41565-019-0442-x

Sunday, 16 June 2019

Molecular assembler creates perfect Qubit


Molecular Assembler

Last month, a New Zealand team was able, for the first time, to put two individual atoms to interact "gently" without colliding and without forcing the bar so they could react.

Now a similar technique has been used to make the atoms react in a very special way, creating a molecule in a perfectly characterized quantum state.


The team used optic tweezers - precisely controlled laser beams to manipulate atoms - to entrap and cool a sodium (Na) atom and a cesium (Cs) atom by pooling and fusing them into a molecule of NaC in a quantum state specific - in this initial experiment, in the lowest energy ground state.

Molecular Qubit

A molecule whose quantum state can be precisely controlled is a promising building block for quantum computers and promises to help researchers study the quantum details of chemical reactions.

Although most of the current qubits are ions - electrically charged atoms -, it is widely recognized that molecules can be qubits better than atoms . In fact, it has recently been shown that a triangular copper molecule is a perfect qubit .

As the tool is generic, taking individual atoms as inputs and fusing into a molecule in a desired state, the team of Professor Kang-Kuen Ni of Harvard University in the USA states that, in addition to a qubit maker, its device is a quantum molecular assembler.

Practical applications

Molecules built into the molecular assembler can serve as qubits capable of storing information for a long time in their highly tuned internal states, which are insensitive to environmental disturbances. And, thanks to the ability of the NaC molecules to interact with each other, each molecular qubit could easily "talk" with other qubits to perform logical operations.


Another application is in the study of chemical reactions. The molecular assembler is used initially to prepare individual molecules in specific quantum states. Next, these molecules are pooled to verify, for example, how the rate of chemical reaction between them depends on these states.


Bibliography:
Molecular Assembly of Ground-State Cooled Single Atoms
L. R. Liu, JD Hood, Y. Yu, JT Zhang, K. Wang, Y.-W. Lin, T. Rosenband, Kang-Kuen Ni
Physical Review X Vol .: 9, 021039 DOI: 10.1103 / PhysRevX.9.021039
Building one molecule from the reservoir of two atoms
LR Liu, JD Hood, Y. Yu, JT Zhang, NR Hutzler , T. Rosenband, Kang-Kuen Ni Science
Vol .: 360, Issue 6391, pp. 900-903 DOI: 10.1126 / science.aar7797