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News Article | November 30, 2016
Site: www.eurekalert.org

Gene therapy gives hope to millions of patients. Researchers from the University of Warsaw have been working on mRNA containing a modified fragment which initiates protein biosynthesis. Recently published results reveal that new compounds - designed and synthesized at the University of Warsaw - are more stable and effective than their natural equivalents, and their synthesis is simpler. The compounds allow scientists to gain a better understanding of the mechanisms of protein biosynthesis in cells, which in turn should help them design better therapeutics. Protein production is frequently disrupted in the cells of a disease-affected organism. This manifests as imbalance in the synthesis of certain proteins or production of damaged proteins, which in extreme cases leads to cancer. Gene therapy is one of the methods used for dealing with this problem. It involves supplying the organism with genetic material encoding proteins whose properties support healthy cell activity. In the early days of experiments on gene therapy, researchers used DNA as the genetic material. However, genes delivered in the form of DNA integrate with the patients' genome, which beside solving the targeted problem, may also bring new serious and unexpected symptoms. Medical researchers have high hopes as to the therapeutic potential of mRNA; the molecules are smaller and simpler, which makes them easier to prepare under laboratory conditions, and - perhaps most importantly - unlike DNA, they don't make permanent changes to the organism's genetic makeup. mRNA molecules are natural polymers formed in cells. They contain precise copes of genes (DNA fragments), so they carry the genetic code and act as templates in the production of new proteins. mRNA molecules are broken down by enzymes after a few minutes or hours. This short lifespan of natural and synthetic mRNA is one of the problems limiting its practical applications. The application of mRNA in gene therapy would be more feasible, if the molecule used in drugs "survived" for longer than its natural equivalent, and if the therapeutic efficacy was as high as possible. The team working on mRNA stabilization was originally founded at the Division of Biophysics (Institute of Experimental Physics, Faculty of Physics, the University of Warsaw). The initiator of research into mRNA structure and function is Prof. Edward Darzynikiewicz (Faculty of Physics, University of Warsaw). The team working on therapeutic modifications of mRNA molecules is led by Prof. Jacek Jemielity, formerly from the Faculty of Physics at the University of Warsaw and currently working at the Centre of New Technologies at the University of Warsaw. The team brings together over a dozen PhD holders and student researchers, with Dr. Joanna Kowalska acting as the main animator of research at the University of Warsaw. The scientists work alongside colleagues from the US and Germany and with pharmaceutical companies. In 2011, the consortium between the University of Warsaw and the Louisiana State University patented and commercialized the team's invention improving the stability and efficiency of mRNA. The solution is currently undergoing clinical tests conducted by one of the pharma partners. The key innovation is the five-prime cap (5' cap) - an artificial mRNA segment replacing its natural 7-methylguanosine structure. The ongoing Warsaw research aims to discover new, better cap analogues, design a technology for large-scale production of therapeutic mRNA, and improve understanding of the course of natural protein synthesis. "The 7-methylguanosine cap is at the 5' end of the mRNA molecule," explains Prof. Darzynkiewicz. "In cytoplasm, the cap structure is recognized by the eIF4E factor which initiates the process of protein biosynthesis, known as translation. This stage decides on the speed of the entire complex sequence of events, which culminate with the synthesis of protein in the cell. The cap protects the mRNA from degradation by cleaving enzymes - nucleases. Unfortunately cells remove the cap using decapping enzymes such as Dcp1/Dcp2. A few years ago we discovered that using modified cap analogues can prevent the degradation of the 5' mRNA end and improve the rate of translation." The team's latest results reveal that the search for new, natural cap analogues is promising. "Our recent paper, published in Nucleic Acids Research,(1) presents a new class of modified caps which are an improved version of those currently undergoing clinical trials," says Prof. Jemielity. "The modification involves swapping an oxygen atom for a sulfur atom in several positions in a specific place of the cap molecule, known as the tri- or tetra-phosphate bridge. mRNA with this chemically modified cap is bound effectively by the eIF4E factor during the stage limiting the speed of protein biosynthesis. It's also highly resistant to the cleaving of the cap structure by the Dcp1/Dcp2 enzyme. Under cellular conditions this mRNA is more stable and produces higher amounts of therapeutic protein, which we have demonstrated in a model used in studies of cancer vaccines. We hope that our modified mRNA will enable us to use lower doses of therapeutics - and lower doses mean a lower risk of side effects." The drug's availability is also very important for the patient. Traditional enzyme methods of modifying caps (and in turn therapeutic mRNA) are time consuming and very ineffective. "Back in 2010, it took us six months to prepare the first four grams of cap needed to start clinical trials, and the amount was barely sufficient to treat 12-13 patients," recalls Dr. Kowalska. Meanwhile, the potential demand can be estimated as kilograms of the compounds every year, leading researchers to seek faster and cheaper production methods. "We turned our attention to click chemistry," says Sylwia Walczak, PhD student at the University of Warsaw. "We have been developing a method of effective synthesis of cap analogues from prefabricated units - chemical 'building blocks'. The structure of each block has at least one fragment which joins its counterpart in another molecule, interlocking like bricks." By applying the method in straightforward production of modified caps, scientists from Poland have developed 36 new analogues. "Two of the compounds have properties we were hoping for: when they are introduced to mRNA, they work as well as the natural cap," adds Anna Nowicka, working on her PhD at the University of Warsaw. "We are certain that this discovery will pave the way to developing new chemical methods of adding the cap to mRNA which will compete with expensive and time consuming enzymatic methods," adds Nowicka. The work of the team of eight authors describing the discovery was published in late summer in the leading journal Chemical Science.(2) The search for new, improved cap analogues slowly shifts from the trial and error approach towards rational design. This is possible due to advances in the understanding of mRNA-related processes, their control and dynamics. Recently, the team from Warsaw contributed to new insights into mRNA decapping "For the first time we have been able to design compounds which, by mimicking the 5' mRNA cap, are able to inhibit the Dcp1/Dcp2 enzyme, which cleaves the cap from mRNA exposing it to degradation," says Dr. Marcin Ziemniak, who completed his PhD at the Faculty of Physics at the University of Warsaw earlier this year. "Working with colleagues at the University of California in San Francisco, John D. Gross and Jeffrey Mugridge, we have used X-ray crystallography to get new insight into structure and function of Dcp1/Dcp2. We have used our compound to capture the key stage of enzyme activity, which is binding the cap. To put it more simply, we used our compound as a bait, which imitates the mRNA cap. The enzymatic complex 'swallows' the bait, 'freezes', and can be 'photographed'. Our results indicate that as the bait is taken - the inhibitor is bound - the enzyme complex undergoes global structural changes. The chemical composition of molecules remains unchanged, of course, but their fragments rotate relative to one another to reach a situation when the enzyme is ready to act." The results have been published in two prestigious journals: RNA (January) and Nature Structural and Molecular Biology (October).(3,4) "We believe that the results will allow us to design even better inhibitors of mRNA decapping," stresses Prof. Jemielity. "They will be useful in further research into mRNA degradation processes, and hopefully they will also find therapeutic applications such as increasing the potency mRNA-based gene therapies." Scientists stress that the problems they are working on require an interdisciplinary approach. "The work we are conducting at the Faculty of Physics is unique," says Dr. Kowalska. "We have access to state-of-the-art research labs, although it's true to say that other teams have similar equipment. Our advantage lies in our team, which consists from experts in biophysics, chemistry and molecular and cellular biology. Conducting research on the boundaries of three different disciplines and the ability to look at the same research problem from different perspectives is incredibly inspirational, and gives us opportunity to come up with completely fresh ideas and solutions which would be far more difficult to reach using just a single approach. I believe this is a unique approach not only in Poland but on a global scale," Kowalska sums up the situation. Physics and Astronomy first appeared at the University of Warsaw in 1816, under the then Faculty of Philosophy. In 1825 the Astronomical Observatory was established. Currently, the Faculty of Physics' Institutes include Experimental Physics, Theoretical Physics, Geophysics, Department of Mathematical Methods and an Astronomical Observatory. Research covers almost all areas of modern physics, on scales from the quantum to the cosmological. The Faculty's research and teaching staff includes ca. 200 university teachers, of which 88 are employees with the title of professor. The Faculty of Physics, University of Warsaw, is attended by ca. 1000 students and more than 170 doctoral students. 1. "Cap analogs modified with 1,2-dithiodiphosphate moiety protect mRNA from decapping and enhance its translational potential", By Malwina Strenkowska, Renata Grzela, Maciej Majewski, Katarzyna Wnek, Joanna Kowalska, Maciej Lukaszewicz, Joanna Zuberek, Edward Darzynkiewicz, Andreas N Kuhn, Ugur Sahin, Jacek Jemielity, Published in Nucleic Acids Research 44 (2016) doi: 10.1093/nar/gkw896, http://nar. 2. "A novel route for preparing 5? cap mimics and capped RNAs: phosphate-modified cap analogues obtained via click chemistry", By Sylwia Walczak, Anna Nowicka, Dorota Kubacka, Kaja Fac, Przemyslaw Wanat, Seweryn Mroczek, Joanna Kowalska, Jacek Jemielity, Published in Chemical Science 7 (2016) DOI: 10.1039/C6SC02437H, http://pubs. 3. "Two-headed tetraphosphate cap analogs are inhibitors of the Dcp1/2 RNA decapping complex", By Marcin Ziemniak, Jeffrey S. Mugridge, Joanna Kowalska, Robert E. Rhoads, John D. Gross, Jacek Jemielity, Published in RNA 22 (2016) 518-529, http://rnajournal. 4. "Structural basis of mRNA-cap recognition by Dcp1-Dcp2", By Jeffrey S. Mugridge, Marcin Ziemniak, Jacek Jemielity, John D. Gross, Published in Nature Structural & Molecular Biology 23 (2016) doi:10.1038/nsmb.3301, http://www. Dr. Joanna Kowalska Institute of Experimental Physics, Faculty of Physics, University of Warsaw tel. +48 22 55 40 774, +48 22 55 40 788 email: asia@biogeo.uw.edu.pl Prof. Edward Darzynkiewicz Institute of Experimental Physics, Faculty of Physics, University of Warsaw tel. +48 22 55 40 787 email: edek@biogeo.uw.edu.pl Prof. Jacek Jemielity Centre of New Technologies, University of Warsaw +48 22 55 43774 e-mail: jacekj@biogeo.uw.edu.pl Press office of the Faculty of Physics, University of Warsaw. FUW161109b_fot01s.jpg HR: http://www. Fragment of the X-ray crystal structure showing the cap bound by Dcp1/Dcp2. Based on pdb-entry 5KQ4. (Source: Faculty of Physics, University of Warsaw)


News Article | November 28, 2016
Site: www.nanotech-now.com

Abstract: A Polish-British team of physicists has constructed and tested a compact, efficient converter capable of modifying the quantum properties of individual photons. The new device should facilitate the construction of complex quantum computers, and in the future may become an important element in global quantum networks, the successors of today's Internet. Quantum internet and hybrid quantum computers, built out of subsystems that operate by means of various physical phenomena, are now becoming more than just the stuff of imagination. In an article just published in the prestigious journal Nature Photonics, physicists from the University of Warsaw's Faculty of Physics (FUW) and the University of Oxford have unveiled a key element of such systems: an electro-optical device that enables the properties of individual photons to be modified. Unlike existing laboratory constructions, this new device works with previously unattainable efficiency and is at the same time stable, reliable, and compact. Building an efficient device for modifying the quantum state of individual photons was an exceptionally challenging task, given the fundamental differences between classical and quantum computing. Contemporary computing systems are based on the processing of groups of bits, each of which is in a specific, well-known state: either 0 or 1. Groups of such bits are continually being transferred both between different subcomponents within a single computer, and between different computers on the network. We can illustrate this figuratively by imagining a situation in which trays of coins are being moved from place to place, with each coin laying either with the heads side or the tails side facing upwards. Things are more complicated in quantum computing, which relies on the phenomenon of superposition of states. A quantum bit, known as a qubit, can be both in the 1 state and the 0 state at the same time. To continue the analogy described above, this would be like a situation in which each coin is spinning on its edge. Information processing can be described as "quantum" processing as long as this superposition of states can be retained during all operations - in other words, as long as none of the coins gets tipped out of the spinning state while the tray is being moved. "In recent years, physicists have figured out how to generate light pulses with a specific wavelength or polarization, consisting of a single quantum -- or excitation -- of the electromagnetic field. And so today we know how to generate precisely whatever kind of quantum 'spinning coins' we want," says Dr. Michal Karpinski from the Institute of Experimental Physics (FUW), one of the authors of the publication. "But achieving one thing always leaves you wanting more! If we now have individual light quanta with specific properties, it would be useful to modify those properties. The task is therefore more or less this: take a spinning silver coin and move it from one place to another, but along the way quickly and precisely turn it into a gold coin, naturally without tipping it over. You can easily see that the problem is nontrivial." Existing methods of modifying individual photons have utilized nonlinear optical techniques, in practice attempting to force an individual photon to interact with a very strong optical pump beam. Whether the photon so subjected actually gets modified is a matter of pure chance. Moreover, the scattering of the pump beam may contaminate the stream of individual photons. In constructing the new device, the group from the University of Warsaw and the University of Oxford decided to make use of a different physical phenomenon: the electro-optic effect occurring in certain crystals. It provides a way to alter the index of refraction for light in the crystal - by varying the intensity of an external magnetic force that is applied to it (in other words, without introducing any additional photons!). "It is quite astounding that in order to modify the quantum properties of individual photons, we can successfully apply techniques very similar to those used in standard fiber-optic telecommunications," Dr. Karpinski says. Using the new device, the researchers managed - without disrupting the quantum superposition! -- to achieve a six-fold lengthening of the duration of a single-photon pulse, which automatically means a narrowing of its spectrum. What is particularly important is that the whole operation was carried out while preserving very high conversion efficiency. Existing converters have operated only under laboratory conditions and were only able to modify one in several tens of photons. The new device works with efficiency in excess of 30%, up to even 200 times better than certain existing solutions, while retaining a low level of noise. "In essence we process every photon entering the crystal. The efficiency is less than 100% not because of the physics of the phenomenon, but on account of hard-to-avoid losses of a purely technical nature, appearing for instance when light enters of exits optical fibers," explains PhD student Michal Jachura (FUW). The new converter is not only efficient and low-noise, but also stable and compact: the device can be contained in a box with dimension not much larger than 10 cm (4 in.), easy to install in an optical fiber system channeling individual photons. Such a device enables us to think realistically about building, for instance, a hybrid quantum computer, the individual subcomponents of which would process information a quantum way using different physical platforms and phenomena. At present, attempts are being made to build quantum computers using, among others, trapped ions, electron spins in diamond, quantum dots, superconducting electric circuits, and atomic clouds. Each such system interacts with light of different properties, which in practice rules out optical transmission of quantum information between different systems. The new converter, on the other hand, can efficiently transform single-photon pulses of light compatible with one system into pulses compatible with another. Scientists are therefore gaining at a real pathway to building quantum networks, both small ones within a single quantum computer (or subcomponent thereof), and global ones providing a way to send data completely securely between quantum computers situated in different parts of the world. ### The experimental part of this work was carried out at the University of Oxford's Department of Physics, in the Optical Quantum Technologies Group led by Dr. Brian J. Smith, where Dr. Karpi?ski had held a postdoctoral fellowship under the prestigious Marie Sklodowska-Curie grants. On the Polish side, the work was funded by grants from Poland's National Science Centre and the 7th EU Framework Programme. About Faculty of Physics University of Warsaw Physics and Astronomy first appeared at the University of Warsaw in 1816, under the then Faculty of Philosophy. In 1825 the Astronomical Observatory was established. Currently, the Faculty of Physics' Institutes include Experimental Physics, Theoretical Physics, Geophysics, Department of Mathematical Methods and an Astronomical Observatory. Research covers almost all areas of modern physics, on scales from the quantum to the cosmological. The Faculty's research and teaching staff includes ca. 200 university teachers, of which 88 are employees with the title of professor. The Faculty of Physics, University of Warsaw, is attended by ca. 1000 students and more than 170 doctoral students. For more information, please click Contacts: Dr. Michal Karpinski 48-225-532-740 M.Sc. Michal Jachura Institute of Theoretical Physics, Faculty of Physics, University of Warsaw tel. 48-22-5532969 If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


News Article | March 1, 2017
Site: www.eurekalert.org

New light is shed on the famous paradox of Einstein, Podolsky and Rosen after 80 years. A group of researchers from the Faculty of Physics at the University of Warsaw has created a multidimensional entangled state of a single photon and a trillion of hot rubidium atoms. This hybrid entanglement has been stored in the laboratory for several microseconds. The research has been published in the prestigious Optica journal. In their famous Physical Review article published in 1935, A. Einstein, B. Podolsky and N. Rosen have considered a decay of a particle into two products. In their thought-experiment, two products of decay were projected in exactly opposite directions, or more scientifically speaking their momenta were anti-correlated. It would not be a mystery within the framework of classical physics, however when applying the rules of the Quantum theory, the three researchers quickly arrived at a paradox. The Heisenberg uncertainty principle, dictating that position and momentum of a particle cannot be measured at the same time within arbitrary precision, lies at the center of this paradox. In Einstein's thought-experiment one can measure momentum of one particle and immediately know momentum of the other without measurement, as it is exactly opposite. Then, one only needs to measure position of this second particle and the Heisenberg uncertainty principle seems to be violated, which seriously baffled the three physicists. Only today we know that this experiment is not, in fact, a paradox. The mistake of Einstein and co-workers was to use one-particle uncertainty principle to a system of two particles. If we treat these two particles as described by a single quantum state, we learn that the original uncertainty principle ceases to apply, especially if these particles are entangled. In the Quantum Memories Laboratory at the University of Warsaw, the group of three physicists was first to create such an entangled state consisting of a macroscopic object - a group of about one trillion atoms, and a single photon - a particle of light. "Single photons, scattered during the interaction of a laser beam with atoms, are registered on a sensitive camera. A single registered photon carries information about the quantum state of the entire group of atoms. The atoms may be stored, and their state may be retrieved on demand." - says Michal Dabrowski, PhD student and co-author of the article. The results of the experiment confirm that the atoms and the single photon are in a joint, entangled state. By measuring position and momentum of the photon, we gain all information about the state of atoms. To confirm this, polish scientists convert the atomic state into another photon, which again is measured using the state-of-the-art camera developed in the Quantum Memories Laboratory. "We demonstrate the Einstein-Podolsky-Rosen apparent paradox in a very similar version as originally proposed in 1935, however we extend the experiment by adding storage of light within the large group of atoms. Atoms store the photon in a form of a wave made of atomic spins, containing one trillion atoms. Such a state is very robust against loss of a single atoms, as information is spread across so many particles." - says Michal Parniak, PhD student taking part in the study. The experiment performed by the group from the University of Warsaw is unique in one other way as well. The quantum memory storing the entangled state, created thanks to "PRELUDIUM" grant from the Poland's National Science Centre and "Diamentowy Grant" from the Polish Ministry of Science and Higher Education, allows for storage of up to 12 photons at once. This enhanced capacity is promising in terms of applications in quantum information processing. "The multidimensional entanglement is stored in our device for several microseconds, which is roughly a thousand times longer than in any previous experiments, and at the same time long enough to perform subtle quantum operations on the atomic state during storage" - explains Dr. Wojciech Wasilewski, group leader of the Quantum Memories Laboratory team. The entanglement in the real and momentum space, described in the Optica article, can be used jointly with other well-known degrees of freedom such as polarization, allowing generation of so-called hyper-entanglement. Such elaborate ideas constitute new and original test of the fundamentals of quantum mechanics - a theory that is unceasingly mysterious yet brings immense technological progress. Physics and Astronomy first appeared at the University of Warsaw in 1816, under the then Faculty of Philosophy. In 1825 the Astronomical Observatory was established. Currently, the Faculty of Physics' Institutes include Experimental Physics, Theoretical Physics, Geophysics, Department of Mathematical Methods and an Astronomical Observatory. Research covers almost all areas of modern physics, on scales from the quantum to the cosmological. The Faculty's research and teaching staff includes ca. 200 university teachers, of which 88 are employees with the title of professor. The Faculty of Physics, University of Warsaw, is attended by ca. 1000 students and more than 170 doctoral students. Dr. Wojciech Wasilewski Institute of Experimental Physics, Faculty of Physics, University of Warsaw tel. +48 22 5532630 email: wojciech.wasilewski@fuw.edu.pl M.Sc. Michal Dabrowski Institute of Experimental Physics, Faculty of Physics, University of Warsaw tel. +48 22 5532629 email: michal.dabrowski@fuw.edu.pl http://psi. Quantum Memories Laboratory, Institute of Experimental Physics, Faculty of Physics, University of Warsaw. http://www. Press office of the Faculty of Physics, University of Warsaw. FUW170301b_fot01s.jpg HR: http://www. Visualization of a hybrid bipartite entanglement between a single photon (blue) and an atomic spin-wave excitation inside quantum memory glass cell, subsequently confirmed in the detection process of a second photon (red). Presented setup enables the demonstration of Einstein-Podolsky-Rosen paradox with true positions and momenta. (Source: UW Physics, Michal Dabrowski) FUW170301b_fot02s.jpg HR: http://www. From right: Michal Parniak uses the green laser to shining the glass cell with quantum memory, holding by Wojciech Wasilewski. Michal Dabrowski makes a simultaneous measurement of position and momentum of photons generated inside the memory. (Source: UW Physics, Mateusz Mazelanik)


News Article | November 22, 2016
Site: www.eurekalert.org

A Polish-British team of physicists has constructed and tested a compact, efficient converter capable of modifying the quantum properties of individual photons. The new device should facilitate the construction of complex quantum computers, and in the future may become an important element in global quantum networks, the successors of today's Internet. Quantum internet and hybrid quantum computers, built out of subsystems that operate by means of various physical phenomena, are now becoming more than just the stuff of imagination. In an article just published in the prestigious journal Nature Photonics, physicists from the University of Warsaw's Faculty of Physics (FUW) and the University of Oxford have unveiled a key element of such systems: an electro-optical device that enables the properties of individual photons to be modified. Unlike existing laboratory constructions, this new device works with previously unattainable efficiency and is at the same time stable, reliable, and compact. Building an efficient device for modifying the quantum state of individual photons was an exceptionally challenging task, given the fundamental differences between classical and quantum computing. Contemporary computing systems are based on the processing of groups of bits, each of which is in a specific, well-known state: either 0 or 1. Groups of such bits are continually being transferred both between different subcomponents within a single computer, and between different computers on the network. We can illustrate this figuratively by imagining a situation in which trays of coins are being moved from place to place, with each coin laying either with the heads side or the tails side facing upwards. Things are more complicated in quantum computing, which relies on the phenomenon of superposition of states. A quantum bit, known as a qubit, can be both in the 1 state and the 0 state at the same time. To continue the analogy described above, this would be like a situation in which each coin is spinning on its edge. Information processing can be described as "quantum" processing as long as this superposition of states can be retained during all operations - in other words, as long as none of the coins gets tipped out of the spinning state while the tray is being moved. "In recent years, physicists have figured out how to generate light pulses with a specific wavelength or polarization, consisting of a single quantum -- or excitation -- of the electromagnetic field. And so today we know how to generate precisely whatever kind of quantum 'spinning coins' we want," says Dr. Michal Karpinski from the Institute of Experimental Physics (FUW), one of the authors of the publication. "But achieving one thing always leaves you wanting more! If we now have individual light quanta with specific properties, it would be useful to modify those properties. The task is therefore more or less this: take a spinning silver coin and move it from one place to another, but along the way quickly and precisely turn it into a gold coin, naturally without tipping it over. You can easily see that the problem is nontrivial." Existing methods of modifying individual photons have utilized nonlinear optical techniques, in practice attempting to force an individual photon to interact with a very strong optical pump beam. Whether the photon so subjected actually gets modified is a matter of pure chance. Moreover, the scattering of the pump beam may contaminate the stream of individual photons. In constructing the new device, the group from the University of Warsaw and the University of Oxford decided to make use of a different physical phenomenon: the electro-optic effect occurring in certain crystals. It provides a way to alter the index of refraction for light in the crystal - by varying the intensity of an external magnetic force that is applied to it (in other words, without introducing any additional photons!). "It is quite astounding that in order to modify the quantum properties of individual photons, we can successfully apply techniques very similar to those used in standard fiber-optic telecommunications," Dr. Karpinski says. Using the new device, the researchers managed - without disrupting the quantum superposition! -- to achieve a six-fold lengthening of the duration of a single-photon pulse, which automatically means a narrowing of its spectrum. What is particularly important is that the whole operation was carried out while preserving very high conversion efficiency. Existing converters have operated only under laboratory conditions and were only able to modify one in several tens of photons. The new device works with efficiency in excess of 30%, up to even 200 times better than certain existing solutions, while retaining a low level of noise. "In essence we process every photon entering the crystal. The efficiency is less than 100% not because of the physics of the phenomenon, but on account of hard-to-avoid losses of a purely technical nature, appearing for instance when light enters of exits optical fibers," explains PhD student Michal Jachura (FUW). The new converter is not only efficient and low-noise, but also stable and compact: the device can be contained in a box with dimension not much larger than 10 cm (4 in.), easy to install in an optical fiber system channeling individual photons. Such a device enables us to think realistically about building, for instance, a hybrid quantum computer, the individual subcomponents of which would process information a quantum way using different physical platforms and phenomena. At present, attempts are being made to build quantum computers using, among others, trapped ions, electron spins in diamond, quantum dots, superconducting electric circuits, and atomic clouds. Each such system interacts with light of different properties, which in practice rules out optical transmission of quantum information between different systems. The new converter, on the other hand, can efficiently transform single-photon pulses of light compatible with one system into pulses compatible with another. Scientists are therefore gaining at a real pathway to building quantum networks, both small ones within a single quantum computer (or subcomponent thereof), and global ones providing a way to send data completely securely between quantum computers situated in different parts of the world. The experimental part of this work was carried out at the University of Oxford's Department of Physics, in the Optical Quantum Technologies Group led by Dr. Brian J. Smith, where Dr. Karpi?ski had held a postdoctoral fellowship under the prestigious Marie Sklodowska-Curie grants. On the Polish side, the work was funded by grants from Poland's National Science Centre and the 7th EU Framework Programme. Physics and Astronomy first appeared at the University of Warsaw in 1816, under the then Faculty of Philosophy. In 1825 the Astronomical Observatory was established. Currently, the Faculty of Physics' Institutes include Experimental Physics, Theoretical Physics, Geophysics, Department of Mathematical Methods and an Astronomical Observatory. Research covers almost all areas of modern physics, on scales from the quantum to the cosmological. The Faculty's research and teaching staff includes ca. 200 university teachers, of which 88 are employees with the title of professor. The Faculty of Physics, University of Warsaw, is attended by ca. 1000 students and more than 170 doctoral students. "Bandwidth manipulation of quantum light by an electro-optic time lens"; M. Karpinski, M. Jachura, L. J. Wright, B. J. Smith; Nature Photonics 2016; DOI: 10.1038/nphoton.2016.228 Dr. Michal Karpinski Institute of Experimental Physics, Faculty of Physics, University of Warsaw tel. 48-22-5532740, 48-22-5548872 email: mkarp@fuw.edu.pl M.Sc. Michal Jachura Institute of Theoretical Physics, Faculty of Physics, University of Warsaw tel. 48-22-5532969 email: michal.jachura@fuw.edu.pl Division of Optics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw. Press office of the Faculty of Physics, University of Warsaw. A single photon -- a carrier of quantum information -- travels like a spinning coin, in a superposition of states. Modyfing its properties is extremely hard and should be done carefully, without destroying the superposition. (Source: FUW, Grzegorz Krzyzewski) A single photon converter (a yellow-orange box) installed on an optical fiber of the laboratory setup. (Source: FUW, Grzegorz Krzyzewski) Usually, due to the properties mismatch, the majority of single photons cannot be effectively stored e.g. in the quantum memory (represented as a white box). The new converter enables to modify the properties of photons so that virtually all of them can be stored inside the memory. (Source: FUW, Grzegorz Krzyzewski)


Light, when strongly concentrated, is enormously powerful. Now, a team of physicists led by Professor Jörg Schreiber from the Institute of Experimental Physics – Medical Physics, which is part of the Munich-Centre for Advanced Photonics (MAP), a Cluster of Excellence at LMU Munich, has used this energy source with explosive effect. The researchers focus high-power laser light onto beads of plastic just a few micrometers in size. The concentrated energy blows the nanoparticles apart, releasing radiation made up of positively charged atoms (protons). Such proton beams could be used in future for treating tumors, and in advanced imaging techniques. Their findings appear in the journal Physical Review E.


Quantum internet and hybrid quantum computers, built out of subsystems that operate by means of physical phenomena, are now more than just the stuff of imagination. In an article published in Nature Photonics, physicists from the University of Warsaw's Faculty of Physics (FUW) and the University of Oxford report the development of a key element of such systems: an electro-optical device that enables the properties of individual photons to be modified. Unlike existing laboratory constructions, this new device works with previously unattainable efficiency and is at the same time stable, reliable and compact. Building an efficient device for modifying the quantum state of individual photons was an exceptionally challenging task, given the fundamental differences between classical and quantum computing. Contemporary computing systems are based on the processing of groups of bits, each of which is in a specific state: either 0 or 1. Groups of such bits are continually transferred between different subcomponents within a single computer, and between different computers on the network. We can illustrate this figuratively by imagining a situation in which trays of coins are being moved from place to place, with each coin showing either heads or tails. Things are more complicated in quantum computing, which relies on the phenomenon of superposition of states. A quantum bit, known as a qubit, can be both in the 1 state and the 0 state at the same time. To extend the metaphor of the coins, this is analogous to a situation in which each coin is spinning on its edge. Information processing can be described as "quantum" processing as long as this superposition of states is retained during all operations—in other words, as long as none of the coins gets tipped out of the spinning state while the tray is being moved. "In recent years, physicists have figured out how to generate light pulses with a specific wavelength or polarization, consisting of a single quantum—or excitation—of the electromagnetic field. And so today, we know how to generate precisely whatever kind of quantum 'spinning coins' we want," says Dr. Michal Karpinski from the Institute of Experimental Physics (FUW), one of the authors of the publication. "But achieving one thing always leaves you wanting more. If we now have individual light quanta with specific properties, it would be useful to modify those properties. The task is therefore to take a spinning silver coin and move it from one place to another, while quickly and precisely turning it into a gold coin, naturally without tipping it over. You can easily see that the problem is nontrivial." Existing methods of modifying individual photons have utilized nonlinear optical techniques—in practice, attempting to force an individual photon to interact with a very strong optical pump beam. Whether the photon actually gets modified is a matter of pure chance. Moreover, the scattering of the pump beam may contaminate the stream of individual photons. In constructing the new device, the group from the University of Warsaw and the University of Oxford decided to use a different physical phenomenon: the electro-optic effect occurring in certain crystals. It provides a way to alter the index of refraction for light in the crystal by varying the intensity of an external magnetic force that is applied to it (in other words, without introducing any additional photons). "It is quite astounding that in order to modify the quantum properties of individual photons, we can successfully apply techniques very similar to those used in standard fiber-optic telecommunications," Dr. Karpinski says. Using the new device, the researchers achieved a six-fold lengthening of the duration of a single-photon pulse without disrupting the quantum superposition, which automatically means a narrowing of its spectrum. What is particularly important is that the whole operation was carried out while preserving very high conversion efficiency. Existing converters have operated only under laboratory conditions and were only able to modify one in several tens of photons. The new device works with efficiency in excess of 30 percent, up to 200 times better than certain existing solutions, while retaining a low level of noise. "In essence, we process every photon entering the crystal. The efficiency is less than 100 percent not because of the physics of the phenomenon, but on account of hard-to-avoid losses of a purely technical nature, appearing, for instance, when light enters or exits optical fibers," explains Ph.D. student Michal Jachura (FUW). The new converter is not only efficient and low-noise, but also stable and compact. The device can be contained in a box around 10 cm (4 in.), easy to install in an optical fiber system channeling individual photons. Such a device could enable building such things as hybrid quantum computers, the individual subcomponents of which would process information using different physical platforms and quantum phenomena. At present, attempts are being made to build quantum computers using things like trapped ions, electron spins in diamond, quantum dots, superconducting electric circuits, and atomic clouds. Each system interacts with light of different properties, which in practice rules out optical transmission of quantum information between different systems. The new converter, on the other hand, can efficiently transform single-photon pulses of light compatible with one system into pulses compatible with another. Scientists are therefore working toward quantum networks, both small ones within a single quantum computer (or subcomponent thereof), and global ones providing a way to send data completely securely between quantum computers situated in different parts of the world. Explore further: More reliable way to produce single photons More information: Michał Karpiński et al, Bandwidth manipulation of quantum light by an electro-optic time lens, Nature Photonics (2016). DOI: 10.1038/nphoton.2016.228


News Article | September 30, 2016
Site: www.cemag.us

Light, when strongly concentrated, is enormously powerful. Now, a team of physicists led by Professor Jörg Schreiber from the Institute of Experimental Physics – Medical Physics, which is part of the Munich-Centre for Advanced Photonics (MAP), a Cluster of Excellence at LMU Munich, has used this energy source with explosive effect. The researchers focus high-power laser light onto beads of plastic just a few micrometers in size. The concentrated energy blows the nanoparticles apart, releasing radiation made up of positively charged atoms (protons). Such proton beams could be used in future for treating tumors, and in advanced imaging techniques. Their findings appear in the journal Physical Review E. At Texas Petawatt Lasers in Austin, the LMU physicists concentrated laser light so strongly on plastic nanobeads that these essentially exploded. In the experiment, approximately one quadrillion billion photons (3 times 1020 photons) were focused onto microspheres of about 500 nanometers in diameter. Each bead consists of about 50 billion carbon and hydrogen atoms and is held in suspension by the electromagnetic fields of a so-called “Paul trap,” where the laser beam can irradiate them. The laser radiation rips away some 15 percent of the electrons bound in these atoms. The remaining, positively charged atomic nuclei are then violently repelled, and the nanospheres explode at speeds of around 10 per cent the speed of light. The radiation from the positively charged particles (protons) then spreads out in all directions. This mode of production of proton beams with laser light promises to open up new opportunities for nuclear medicine — for example, in the fight against tumors. At present, proton beams are produced in conventional accelerators. In contrast, laser-generated proton beams open the door to the development of novel, perhaps even cheaper and more efficient, methods of treatment. The Munich-based team led by Schreiber has hitherto produced proton radiation using a diamond-like film, which is targeted by extremely strong laser light. The proton radiation thus emitted could then be directed onto the body of a patient. The ability to produce radiation by the explosive disintegration of plastic nanobeads might even allow the nanoparticles to be placed inside a tumor, and be vaporized with laser light. Thus proton beams could be put to work in destroying tumors without causing damage to surrounding healthy tissue.


News Article | December 5, 2016
Site: www.scientificcomputing.com

A Polish-British team of physicists has constructed and tested a compact, efficient converter capable of modifying the quantum properties of individual photons. The new device should facilitate the construction of complex quantum computers, and in the future may become an important element in global quantum networks, the successors of today's Internet. Quantum internet and hybrid quantum computers, built out of subsystems that operate by means of various physical phenomena, are now becoming more than just the stuff of imagination. In an article just published in the prestigious journal Nature Photonics, physicists from the University of Warsaw's Faculty of Physics (FUW) and the University of Oxford have unveiled a key element of such systems: an electro-optical device that enables the properties of individual photons to be modified. Unlike existing laboratory constructions, this new device works with previously unattainable efficiency and is at the same time stable, reliable, and compact. Building an efficient device for modifying the quantum state of individual photons was an exceptionally challenging task, given the fundamental differences between classical and quantum computing. Contemporary computing systems are based on the processing of groups of bits, each of which is in a specific, well-known state: either 0 or 1. Groups of such bits are continually being transferred both between different subcomponents within a single computer, and between different computers on the network. We can illustrate this figuratively by imagining a situation in which trays of coins are being moved from place to place, with each coin laying either with the heads side or the tails side facing upwards. Things are more complicated in quantum computing, which relies on the phenomenon of superposition of states. A quantum bit, known as a qubit, can be both in the 1 state and the 0 state at the same time. To continue the analogy described above, this would be like a situation in which each coin is spinning on its edge. Information processing can be described as "quantum" processing as long as this superposition of states can be retained during all operations - in other words, as long as none of the coins gets tipped out of the spinning state while the tray is being moved. "In recent years, physicists have figured out how to generate light pulses with a specific wavelength or polarization, consisting of a single quantum -- or excitation -- of the electromagnetic field. And so today we know how to generate precisely whatever kind of quantum 'spinning coins' we want," says Dr. Michal Karpinski from the Institute of Experimental Physics (FUW), one of the authors of the publication. "But achieving one thing always leaves you wanting more! If we now have individual light quanta with specific properties, it would be useful to modify those properties. The task is therefore more or less this: take a spinning silver coin and move it from one place to another, but along the way quickly and precisely turn it into a gold coin, naturally without tipping it over. You can easily see that the problem is nontrivial." Existing methods of modifying individual photons have utilized nonlinear optical techniques, in practice attempting to force an individual photon to interact with a very strong optical pump beam. Whether the photon so subjected actually gets modified is a matter of pure chance. Moreover, the scattering of the pump beam may contaminate the stream of individual photons. In constructing the new device, the group from the University of Warsaw and the University of Oxford decided to make use of a different physical phenomenon: the electro-optic effect occurring in certain crystals. It provides a way to alter the index of refraction for light in the crystal - by varying the intensity of an external magnetic force that is applied to it (in other words, without introducing any additional photons!). "It is quite astounding that in order to modify the quantum properties of individual photons, we can successfully apply techniques very similar to those used in standard fiber-optic telecommunications," Dr. Karpinski says. Using the new device, the researchers managed - without disrupting the quantum superposition! -- to achieve a six-fold lengthening of the duration of a single-photon pulse, which automatically means a narrowing of its spectrum. What is particularly important is that the whole operation was carried out while preserving very high conversion efficiency. Existing converters have operated only under laboratory conditions and were only able to modify one in several tens of photons. The new device works with efficiency in excess of 30%, up to even 200 times better than certain existing solutions, while retaining a low level of noise. "In essence we process every photon entering the crystal. The efficiency is less than 100% not because of the physics of the phenomenon, but on account of hard-to-avoid losses of a purely technical nature, appearing for instance when light enters of exits optical fibers," explains PhD student Michal Jachura (FUW). The new converter is not only efficient and low-noise, but also stable and compact: the device can be contained in a box with dimension not much larger than 10 cm (4 in.), easy to install in an optical fiber system channeling individual photons. Such a device enables us to think realistically about building, for instance, a hybrid quantum computer, the individual subcomponents of which would process information a quantum way using different physical platforms and phenomena. At present, attempts are being made to build quantum computers using, among others, trapped ions, electron spins in diamond, quantum dots, superconducting electric circuits, and atomic clouds. Each such system interacts with light of different properties, which in practice rules out optical transmission of quantum information between different systems. The new converter, on the other hand, can efficiently transform single-photon pulses of light compatible with one system into pulses compatible with another. Scientists are therefore gaining at a real pathway to building quantum networks, both small ones within a single quantum computer (or subcomponent thereof), and global ones providing a way to send data completely securely between quantum computers situated in different parts of the world.


Drennov O.B.,Institute of Experimental Physics
Journal of Applied Mechanics and Technical Physics | Year: 2015

Results of experiments on loading a pack of closely packed metal plates by an oblique shock wave are reported. Buckling of the interface between the plate is observed. It is shown that periodic wavy perturbations are formed due to the development of the Kelvin–Helmholtz instability within the time of interface turning induced by the shock wave action. The final amplitude and wavelength of perturbations are found to be determined by the thickness of the weakened layer in a plastic flow. © 2015, Pleiades Publishing, Ltd.


Phan T.H.,University of Bonn | Wandelt K.,University of Bonn | Wandelt K.,Institute of Experimental Physics
International Journal of Molecular Sciences | Year: 2013

The self-assembly of molecular layers has become an important strategy in modern design of functional materials. However, in particular, large organic molecules may no longer be sufficiently volatile to be deposited by vapor deposition. In this case, deposition from solution may be a promising route; in ionic form, these molecules may even be soluble in water. In this contribution, we present and discuss results on the electrochemical deposition of viologen- and porphyrin molecules as well as their co-adsorption on chloride modified Cu(100) and Cu(111) single crystal electrode surfaces from aqueous acidic solutions. Using in situ techniques like cyclic voltametry and high resolution scanning tunneling microscopy, as well as ex-situ photoelectron spectroscopy data the highly ordered self-assembled organic layers are characterized with respect to their electrochemical behavior, lateral order and inner conformation as well as phase transitions thereof as a function of their redox-state and the symmetry of the substrate. As a result, detailed structure models are derived and are discussed in terms of the prevailing interactions. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

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