INFORMATION:
Researchers realize high-efficiency frequency conversion on integrated photonic chip
2021-04-23
(Press-News.org) A team led by Prof. GUO Guangcan and Prof. ZOU Changling from the University of Science and Technology of China of the Chinese Academy of Sciences realized efficient frequency conversion in microresonators via a degenerate sum-frequency process, and achieved cross-band frequency conversion and amplification of converted signal through observing the cascaded nonlinear optical effects inside the microresonator. The study was published in Physics Review Letters.
Coherent frequency conversion process has wide application in classical and quantum information fields such as communication, detection, sensing, and imaging. As a bridge connecting wavebands between fiber telecommunications and atomic transition, coherent frequency conversion is a necessary interface for distributed quantum computing and quantum networks.
Integrated nonlinear photonic chip stands out because of its significant technological advances of improving nonlinear optical effects by microresonator's enhancing the light-matter interaction, along with other advantages like small size, great scalability, and low energy consumption. These make integrated nonlinear photonic chips an important platform to covert optical frequency efficiently and realize other nonlinear optical effects.
However, the on-chip resonant-enhanced coherent frequency conversion requires multiple (three or more) modes of phase matching condition among distinct wavelengths, which imposes significant challenges to the devices' design, fabrication, and modulation. Especially in the application of atomic and molecular spectroscopy, the intrinsic error brought by nanofabrication technique of integrated nonlinear photonic chips makes the resonant frequency of microresonator hard to match atomic transition frequency.
The researchers in this study proposed a new scheme for high-efficiency coherent frequency conversion requiring only the two-mode phase matching condition via a degenerate sum-frequency process. They achieved precise tuning of the frequency window (FW): coarse tuning by adjusting the device temperature with a tuning range of 100 GHz; fine tuning with MHz level based on previous work of all-optical thermal control in an integrated microcavity.
The results showed that the best achieved efficiency was up to 42% during the photon-number conversion from 1560-nm-wide to 780-nm-wide wavelength, indicating a frequency tuning bandwidth over 250GHz. This satisfied the interconnection of telecom photons and rubidium (Rb) atoms.
Besides, the researchers experimentally verified cascaded χ(2) and Kerr nonlinear optical effects inside a single microresonator to amplify the converted signal, which was neglected before. Thus the highest conversion efficiency was potential to achieve over 100% through adjusting device fabrication parameters, fulfilling simultaneously signal converted and amplified.
This study provides a novel way for efficient on-chip frequency conversion, which is extremely important for on-chip quantum information processing.
ELSE PRESS RELEASES FROM THIS DATE:
Heartbeat can help detect signs of consciousness in patients after a coma
2021-04-23
A new study conducted jointly by the University of Liege (Belgium) and the Ecole normale superieure - PSL (France) shows that heart brain interactions, measured using electroencephalography (EEG), provide a novel diagnostic avenue for patients with disorders of consciousness. This study is published in the Journal of Neuroscience.
Catherine Tallon-Baudry (ENS, CNRS) introduces : "The scientific community already knew that in healthy participants, the brain's response to heartbeats is related to perceptual, bodily and self-consciousness. We now show that we can obtain clinically meaningful information if we probe this interaction in ...
VR visualization supports research on molecular networks
2021-04-23
Networks offer a powerful way to visualize and analyze complex systems. However, depending on the size and complexity of the network, many visualizations are limited. Protein interactions in the human body constitute such a complex system that can hardly be visualized. Jörg Menche, Adjunct Principal Investigator at the CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Professor at the University of Vienna and research group leader at Max Perutz Labs (Uni Wien/MedUni), and his team developed an immersive virtual reality (VR) platform that solves ...
An easy-to-use platform is a gateway to AI in microscopy
2021-04-23
Software using artificial intelligence, AI, is revolutionizing how microscopy images are analysed. For instance, AI can be used to detect features in images (i.e., tumours in biopsy samples) or improve the quality of images by removing unwanted noise. However, non-experts continue to find AI technologies difficult to use.
In the article "Democratising deep learning for microscopy with ZeroCostDL4Mic", published in Nature Communications on 15 April 2021, researchers describe a platform called ZeroCostDL4Mic, which makes these AI technologies accessible to everyone.
"The key novelty is that ZeroCostDL4Mic runs in the cloud for free and does not ...
From individual receptors towards whole-brain function
2021-04-23
In the brain, more than a hundred molecular substances act as transmitters that control communication pathways between nerve cells via thousands of different receptor types. In a review article, an international research team discusses how the activation of certain nerve cell receptors affects neuronal networks in the brain. The authors from Ruhr-Universität Bochum (RUB), Pompeu Fabra University in Barcelona and Oxford University present concepts to quantify receptor-specific modulations of brain states. They have also developed a computer model that can predict the impact of individual receptor types on brain activity.
In addition, the researchers show how the predictions obtained in the computer can be verified and refined by experimental methods. They hope this will lead to new ...
Scientists probe mysterious melting of Earth's crust in western North America
2021-04-23
A group of University of Wyoming professors and students has identified an unusual belt of igneous rocks that stretches for over 2,000 miles from British Columbia, Canada, to Sonora, Mexico.
The rock belt runs through Idaho, Montana, Nevada, southeast California and Arizona.
"Geoscientists usually associate long belts of igneous rocks with chains of volcanoes at subduction zones, like Mount Shasta, Mount Hood, Mount St. Helens and Mount Rainer," says Jay Chapman, an assistant professor in UW's Department of Geology and Geophysics. "What makes this finding so interesting and mysterious is that this belt ...
Individual receptors caught in the act of coupling
2021-04-23
NEW YORK, NY--A new imaging technique developed by scientists at Columbia University Vagelos College of Physicians and Surgeons and St. Jude Children's Research Hospital captures movies of receptors on the surface of living cells in unprecedented detail and could pave the way to a trove of new drugs.
The researchers used the technique to zoom in on individual receptor proteins on the surface of living cells to determine if the receptors work solo or come together to work as pairs. This work appeared in the April issue of Nature Methods.
"If two different receptors come together to form a dimer with distinctive function and pharmacology, this might allow for a new generation of drugs with greater specificity and reduced side effects," says Jonathan ...
People with heart rhythm disorders warned over cannabis use
2021-04-23
Sophia Antipolis - 23 April 2021: A study of 2.4 million hospitalised cannabis users has found that those with an arrhythmia were 4.5 times more likely to die while in hospital than those without. The research is presented at EHRA 2021, an online scientific congress of the European Society of Cardiology (ESC).1
"People should be aware of this devastating outcome and be careful when using cannabis if they have a concomitant heart problem," said study author Dr. Sittinun Thangjui of Bassett Healthcare Network, Cooperstown, US.
Marijuana or cannabis is the most commonly used psychoactive substance worldwide.2 However, there is limited knowledge about safety of the drug in people with cardiac arrhythmias. This study examined the burden ...
Patching up your health
2021-04-23
Osaka, Japan - Scientists at Osaka University, in cooperation with JOANNEUM RESEARCH (Weiz, Austria), introduced wireless health monitoring patches that use embedded piezoelectric nanogenerators to power themselves with harvested biomechanical energy. This work may lead to new autonomous health sensors as well as battery-less wearable electronic devices.
As wearable technology and smart sensors become increasingly popular, the problem of providing power to all of these devices become more relevant. While the energy requirements of each component may be modest, the need for wires or even batteries become burdensome and inconvenient. That is why new energy harvesting methods are needed. Also, the ability ...
With new optical device, engineers can fine tune the color of light
2021-04-23
Among the first lessons any grade school science student learns is that white light is not white at all, but rather a composite of many photons, those little droplets of energy that make up light, from every color of the rainbow - red, orange, yellow, green, blue, indigo, violet.
Now, researchers at Stanford University have developed an optical device that allows engineers to change and fine-tune the frequencies of each individual photon in a stream of light to virtually any mixture of colors they want. The result, published April 23 in Nature Communication, is a new photonic architecture that could transform fields ranging from digital communications and artificial intelligence to cutting-edge quantum computing.
"This powerful new tool puts a degree of control in the engineer's ...
Quantum steering for more precise measurements
2021-04-23
Quantum systems consisting of several particles can be used to measure magnetic or electric fields more precisely. A young physicist at the University of Basel has now proposed a new scheme for such measurements that uses a particular kind of correlation between quantum particles.
In quantum information, the fictitious agents Alice and Bob are often used to illustrate complex communication tasks. In one such process, Alice can use entangled quantum particles such as photons to transmit or "teleport" a quantum state - unknown even to herself - to Bob, something that is not feasible using traditional communications.
However, it has been unclear whether the team Alice-Bob can use similar quantum states for other things besides communication. A young physicist at the University ...