Not one, not two, not three, but four clones: First quantum cloning machine to produce four copies

ScienceDaily (Nov. 6, 2011) — Xi-Jun Ren and Yang Xiang from Henan Universities in China, in collaboration with Heng Fan at the Institute of Physics of the Chinese Academy of Sciences, have produced a theory for a quantum cloning machine able to produce several copies of the state of a particle at atomic or sub-atomic scale, or quantum state, in an article about to be published in The European Physical Journal D. The advance could have implications for quantum information processing methods used, for example, in message encryption systems.

Quantum cloning is difficult because quantum mechanics laws only allow for an approximate copy—not an exact copy—of an original quantum state to be made, as measuring such a state prior to its cloning would alter it.

In this study, researchers have demonstrated that it is theoretically possible to create four approximate copies of an initial quantum state, in a process called asymmetric cloning. The authors have extended previous work that was limited to quantum cloning providing only two or three copies of the original state. One key challenge was that the quality of the approximate copy decreases as the number of copies increases.

The authors were able to optimise the quality of the cloned copies, thus yielding four good approximations of the initial quantum state. They have also demonstrated that their quantum cloning machine has the advantage of being universal and therefore is able to work with any quantum state, ranging from a photon to an atom.

Assymetric quantum cloning has applications in analysing the security of messages encryption systems, based on shared secret quantum keys. Two people will know whether their communication is secure by analysing the quality of each copy of their secret key. Any third party trying to gain knowledge of that key would be detected as measuring it would disturb the state of that key.

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Journal Reference:

X. J. Ren, Y. Xiang, H. Fan. Optimal asymmetric 1 ? 4 quantum cloning in arbitrary dimension. The European Physical Journal D, 2011; DOI: 10.1140/epjd/e2011-20370-2

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'Magnetic tongue' ready to help produce tastier processed foods

ScienceDaily (Oct. 26, 2011) — The "electronic nose," which detects odors, has a companion among emerging futuristic "e-sensing" devices intended to replace abilities that once were strictly human-and-animal-only. It is a "magnetic tongue" -- a method used to "taste" food and identify ingredients that people describe as sweet, bitter, sour, etc. A report on use of the method to taste canned tomatoes appears in ACS' Journal of Agricultural and Food Chemistry.

Antonio Randazzo, Anders Malmendal, Ettore Novellino and colleagues explain that sensing the odor and flavor of food is a very complex process. It depends not only on the combination of ingredients in the food, but also on the taster's emotional state. Trained taste testers eliminate some of the variation, but food processors need more objective ways to measure the sensory descriptor of their products. That's where electronic sensing technologies, like E-noses, come into play.

However, current instruments can only analyze certain food components and require very specific sample preparation. To overcome these shortcomings, Randazzo and Malmendal's team turned to nuclear magnetic resonance spectroscopy (NMR) to test its abilities as "a magnetic tongue."

The researchers analyzed 18 canned tomato products from various markets with NMR and found that the instrument could estimate most of the tastes assessed by the human taste testers. But the NMR instrument went even farther. By determining the chemical composition, it showed which compound is related to which sensory descriptor. The researchers say that the "magnetic tongue" has good potential as a rapid, sensitive and relatively inexpensive approach for food processing companies to use.

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The above story is reprinted from materials provided by American Chemical Society.

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Journal Reference:

Anders Malmendal, Claudia Amoresano, Roberta Trotta, Ilaria Lauri, Stefano De Tito, Ettore Novellino, Antonio Randazzo. NMR Spectrometers as “Magnetic Tongues”: Prediction of Sensory Descriptors in Canned Tomatoes. Journal of Agricultural and Food Chemistry, 2011; 59 (20): 10831 DOI: 10.1021/jf203803q

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Laser ion source will produce a new generation of semiconductors

ScienceDaily (Oct. 20, 2011) — For ion implantation, that is 'hammering' ions into the surface layer of the material, conventional ion accelerators are commonly used. Laser ion sources are much simpler, cheaper and more universal. However, they emit wide energy ions usually accompanied by some admixtures. In the Institute of Plasma Physics and Laser Microfusion in Warsaw a unique laser ion source has been built which is equipped with a special system for accelerating ions to a chosen energy and for eliminating admixtures. This device has already been used to produce samples of a new generation of semiconductors: a layer of silica (SiO2) in which germanium nanocrystals have been formed.

Laser Ion Sources (LIS) are simple devices that produce ions in interaction of a focused laser beam with the target placed in a vacuum vessel. Admixtures that happen to be in the target often cause problems -- together with the proper ions, they can modify the sample. Moreover, the laser pulse also pulls out atoms and debris from the target which are deposited on the irradiated sample and modify its surface. "To prevent such effects, we have designed and built a device for ion implantation with a unique electric system for ion acceleration," says Marcin Rosinski, a PhD student from the Institute of Plasma Physics and Laser Microfusion (IPPLM) in Warsaw.

Ion implementation is the process of embedding ions into the surface layer of the sample in order to change some properties of the material, mechanical or electrical. Currently, ion accelerators are routinely used for this purpose. Laser ion sources have a chance to excel those devices: they are smaller, simpler and can produce ions from high-melting materials such as tantalum or tungsten. What is more, the ion beam can easily be modified by the change of parameters and the geometry of the laser-target-sample system. The released ions can well be accelerated in the external electric field.

However, to be able to use the LIS type sources in industry, some requirements must be fulfilled: the beam of ions cannot possess impurities and the ions should have almost the same specific energy. To meet both requirements the laser ion source with special electrostatic system must be applied.

In the device built at the IPPLM the low-energy laser pulse lasts 3.5 nanoseconds. The laser pulse energy, in the first phase of laser-matter interaction, is transferred to free electrons which subsequently ionise atoms of target material and admixtures. The main part of the laser pulse energy directly heats ionised matter (plasma) causing its quick expansion. A broad energy distribution of the ions expanding from plasma results from the nature of the process of plasma generation.

Some particles and debris extracted from the target by the laser pulse are electrically neutral, which is why they expand without deflection in the electric field and go straight onto the screen that is placed exactly on the axis of the system, to shield the sample. At the same time, laser-produced ions which avoid the screen are accelerated and focused by the electric field on the sample located on the axis behind the screen. "We have selected the parameters of the field in such a way that only the chosen ions of the target reach the sample. The spot of the focused beam is 1 mm in diameter," explains Rosinski.

The low-energy laser used in the experiment does not heat itself and is capable of generating 10 thousand or more laser pulses within some ten minutes. Those advantages make it possible for scientists to control precisely the number of ions that reach the sample.

The solution proposed by the scientists from the IPPLM has successfully been used to explore the process of germanium ion implantation in silica (SiO2) layer with a view to fabricate germanium nanocrystals within it. Thus, a modified semiconductor has been created whose prospective implementation in electronics is widely anticipated, for example in miniaturisation of some memory chips or in elements for light emission.

To obtain germanium nanocrystals from the laser-produced ions, the implanted sample should be heated in the temperature of 600 to 1200 Celsius degrees. In this process some germanium crystals, ranging in size from a few to 20 nanometres (billionth of a metre) are created. "Our implanted samples, after heating, are examined with the use of various sophisticated, currently available measuring methods in the specialised laboratories, mainly at the Universities in Messina and Catania in Sicily. We have analysed both the results of ion implantation and the formation of nanocrystal structures in the samples," says Rosinski.

Laser ion source built and tested at the IPPLM is a prototype device expected to find applications in industry. "In two years, we will have finished the work connected with optimization of our device regarding industrial usage but we have already started looking for enterprises that are interested in implementing this technology," summarises Prof. Jerzy Wolowski, the Head of Laser Plasma Division at the IPPLM.

The construction of the device for laser induced implantation was started at the IPPLM a few years ago within the framework of European SEMINANO project.

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Laser ion source will produce a new generation of semiconductors

ScienceDaily (Oct. 20, 2011) — For ion implantation, that is 'hammering' ions into the surface layer of the material, conventional ion accelerators are commonly used. Laser ion sources are much simpler, cheaper and more universal. However, they emit wide energy ions usually accompanied by some admixtures. In the Institute of Plasma Physics and Laser Microfusion in Warsaw a unique laser ion source has been built which is equipped with a special system for accelerating ions to a chosen energy and for eliminating admixtures. This device has already been used to produce samples of a new generation of semiconductors: a layer of silica (SiO2) in which germanium nanocrystals have been formed.

Laser Ion Sources (LIS) are simple devices that produce ions in interaction of a focused laser beam with the target placed in a vacuum vessel. Admixtures that happen to be in the target often cause problems -- together with the proper ions, they can modify the sample. Moreover, the laser pulse also pulls out atoms and debris from the target which are deposited on the irradiated sample and modify its surface. "To prevent such effects, we have designed and built a device for ion implantation with a unique electric system for ion acceleration," says Marcin Rosinski, a PhD student from the Institute of Plasma Physics and Laser Microfusion (IPPLM) in Warsaw.

Ion implementation is the process of embedding ions into the surface layer of the sample in order to change some properties of the material, mechanical or electrical. Currently, ion accelerators are routinely used for this purpose. Laser ion sources have a chance to excel those devices: they are smaller, simpler and can produce ions from high-melting materials such as tantalum or tungsten. What is more, the ion beam can easily be modified by the change of parameters and the geometry of the laser-target-sample system. The released ions can well be accelerated in the external electric field.

However, to be able to use the LIS type sources in industry, some requirements must be fulfilled: the beam of ions cannot possess impurities and the ions should have almost the same specific energy. To meet both requirements the laser ion source with special electrostatic system must be applied.

In the device built at the IPPLM the low-energy laser pulse lasts 3.5 nanoseconds. The laser pulse energy, in the first phase of laser-matter interaction, is transferred to free electrons which subsequently ionise atoms of target material and admixtures. The main part of the laser pulse energy directly heats ionised matter (plasma) causing its quick expansion. A broad energy distribution of the ions expanding from plasma results from the nature of the process of plasma generation.

Some particles and debris extracted from the target by the laser pulse are electrically neutral, which is why they expand without deflection in the electric field and go straight onto the screen that is placed exactly on the axis of the system, to shield the sample. At the same time, laser-produced ions which avoid the screen are accelerated and focused by the electric field on the sample located on the axis behind the screen. "We have selected the parameters of the field in such a way that only the chosen ions of the target reach the sample. The spot of the focused beam is 1 mm in diameter," explains Rosinski.

The low-energy laser used in the experiment does not heat itself and is capable of generating 10 thousand or more laser pulses within some ten minutes. Those advantages make it possible for scientists to control precisely the number of ions that reach the sample.

The solution proposed by the scientists from the IPPLM has successfully been used to explore the process of germanium ion implantation in silica (SiO2) layer with a view to fabricate germanium nanocrystals within it. Thus, a modified semiconductor has been created whose prospective implementation in electronics is widely anticipated, for example in miniaturisation of some memory chips or in elements for light emission.

To obtain germanium nanocrystals from the laser-produced ions, the implanted sample should be heated in the temperature of 600 to 1200 Celsius degrees. In this process some germanium crystals, ranging in size from a few to 20 nanometres (billionth of a metre) are created. "Our implanted samples, after heating, are examined with the use of various sophisticated, currently available measuring methods in the specialised laboratories, mainly at the Universities in Messina and Catania in Sicily. We have analysed both the results of ion implantation and the formation of nanocrystal structures in the samples," says Rosinski.

Laser ion source built and tested at the IPPLM is a prototype device expected to find applications in industry. "In two years, we will have finished the work connected with optimization of our device regarding industrial usage but we have already started looking for enterprises that are interested in implementing this technology," summarises Prof. Jerzy Wolowski, the Head of Laser Plasma Division at the IPPLM.

The construction of the device for laser induced implantation was started at the IPPLM a few years ago within the framework of European SEMINANO project.

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The above story is reprinted from materials provided by Institute of Plasma Physics and Laser Microfusion, via AlphaGalileo.

Note: ScienceDaily reserves the right to edit materials for content and length. For further information, please contact the source cited above.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

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