Researchers in Italy have calculated that the Nobel Prize-winning device called a Josephson junction could precisely convert a signal from megahertz to gigahertz -- with potential uses in metrology and telecommunications
The manipulation of electromagnetic radiation is an essential function of today's technology. Low frequency radiation -- in the kilohertz and megahertz range -- is easier to generate than gigahertz radiation. Yet higher frequencies can carry more information and travel farther.
Josephson junctions consist of a thin layer of insulator sandwiched between two superconducting layers. Researchers from Italy found that Josephson junctions placed in an oscillating magnetic field produced voltage pulses and that changing the shape of the Josephson junction changed the amount of power at different output frequencies. A ring-shaped junction produced more power at higher harmonics than did a circular or rectangular junction.
Credit: P. Solinas, et al. / JAP
Now researchers from the Italian National Research Council (SPIN-CNR) and the National Enterprise for nanoScience and nanoTechnology (NEST-CNR) in Italy have devised a novel, inexpensive way to turn low frequency signals into higher frequencies.
The approach makes use of a Nobel Prize-winning device called a Josephson junction, which is currently used to make extremely sensitive voltmeters and detect minute changes in magnetic fields. The researchers describe their new application in the Journal of Applied Physics, from AIP Publishing.
Josephson junctions consist of a thin layer of insulator sandwiched between two superconducting layers. Under the right conditions, electrons can travel from one superconducting layer to the other with no resistance through the insulator in the middle. When the current reaches a critical level, however, a finite resistance suddenly appears and a voltage develops across the device.
Paolo Solinas, a physicist at the Italian National Research Council, was experimenting on Josephson junctions with his colleagues at NEST-CNR when they noticed an unusual behavior. They found that Josephson junctions placed in an oscillating magnetic field produced voltage pulses. The researchers turned to theory to analyze and explain the behavior.
They found that an oscillating magnetic field produced a sudden jump in a quantum mechanical property of the superconductor layers called a phase. The phase jump in turn produced the voltage pulse. The researchers also found that a regularly time-dependent magnetic field would produce voltage pulses that contained hundreds of harmonics of the original driving frequency, including frequencies thousands of times higher.
"The output of a single device is small, but you could build an array of devices to turn low power intrinsic of a single junction into higher output power," Solinas said. The team calculated that stringing together 1,000 Josephson junctions made from niobium and aluminum oxide could convert a 100 MHz input frequency into a 100 picowatt signal at 50 GHz.
The researchers also found that changing the shape of the Josephson junction changed the amount of power at different output frequencies. They found that a ring-shaped junction produced more power at higher harmonics than did a circular or rectangular junction.
A frequency converter made from Josephson junctions would be a totally different type of signal generator from what's currently used, Solinas noted. Most gigahertz signal generators are bulky and expensive. Electronic circuits made from Josephson junctions could be mere millimeters long and integrate easily into electronic chips.
"So far we have theoretical results, but we are really looking forward to having a match with experiment," Solinas said. The team hopes their initial finding will interest others in building the devices. At first the technology would likely be used in the lab to calibrate measurements and perform experiments, Solinas said. With further development, it might also be used by the telecommunications industry.
The article, "Radiation comb generation with extended Josephson junctions," is authored by P. Solinas, R. Bosisio and F. Giazotto. It will be published in the Journal of Applied Physics on September 15, 2015 (DOI: 10.1063/1.4928679). After that date, it can be accessed at: http://scitation.
The authors of this paper are affiliated with the Italian National Research Council (SPIN-CNR) and the National Enterprise for nanoScience and nanoTechnology (NEST-CNR) in Italy.
ABOUT THE JOURNAL
Journal of Applied Physics is an influential international journal publishing significant new experimental and theoretical results of applied physics research. See: http://jap.
Jason Socrates Bardi | EurekAlert!
NASA spacecraft investigate clues in radiation belts
28.03.2017 | NASA/Goddard Space Flight Center
Researchers create artificial materials atom-by-atom
28.03.2017 | Aalto University
The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.
To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
28.03.2017 | Life Sciences
28.03.2017 | Information Technology
28.03.2017 | Physics and Astronomy