Speculative Meteorology: Weather Channeled Feb 3-7, [2-25] 10-4pm [ET]
opening reception : Feb 5, [2025] 5-7pm [ET] Special Projects Gallery, Goldfarb Centre for the Arts York University [Toronto, Ontario, Canada]
Curated by Aftab Mirzaei (Science and Technology Studies) with Mark-David Hosale (Digital Media) and showcases the work of artists and researchers including, Chris Beaulieu, Kwame Kyei-Boateng, Nava Waxman, Mark-David Hosale, Hiro Kubayashi, Grace Grothaus, Leo Liu, Winnie Luo, Aftab Mirzaei, and Colin Tucker.
DESCRIPTION Speculative Meteorology: Weather Channeled emerges from a series of interdisciplinary experiments conducted by members of the nd:studiolab between 2023 and 2024. This exhibit invites artists and researchers to explore imaginative and multidimensional accounts of atmospheres and climates across past, present, and future. Drawing on Donna Haraway’s concept of SF—speculative fabulation as a mode of attention, a theory of history, and a practice of worlding—the works collectively reimagine our relationship to the weather, engaging it as a site of both knowledge-making and creative practice.
Sponsored by the nD::StudioLab at York University
Environmental Monitoring for Art a workshop as part of the Speculative Meteorology: Weather Channeled interdisciplinary art exhibition, with Grace Grothaus
Feb 7, 2025, 12 -3 PM [ET] ACW 103, The Transmedia Lab York University [Toronto, Ontario, Canada]
In this three-hour workshop, we will fabricate sensors that can detect environmental data using some readily available materials and electronics. We will fabricate sensors that can detect animal footsteps, record raindrops, or measure wind and then learn to read their values using Arduino. The data from these sensors can be used as input for actuators in physical computing projects, or they can be triggers for screen-based animation or music – the options are wide and varied.
Here’s the second exhibition and its associated events, from the January 25, 2025 notice,
Afterglow Exhibition Feb 4-7, [2-25] 10-3pm [ET]
opening reception : Feb 5, [2025] 5-7pm [ET] Gales Gallery, York University [Toronto, Ontario, Canada]
Curated by : Nina Czegledy & Joel Ong, featuring international and local artists Raphael Arar, Nagy Molnar, Laszlo Zsolt Bordos, Jennifer Willet, Joel Ong (with Khaled Eilouti, Zhino Yousefi, Shelby Murchie and Oliver Debski-Tran)
AFTERGLOW [ af-ter-gloh, ahf- ] is an exhibition envisioned around the graphic quality of light, as well as its traces and incandescence both real and metaphorical. The participating artists explore cross-cultural practices via a variety of analog and digital media, relating light to unfolding contemporary considerations in the global Light Art panorama. At the same time, Afterglow references a deep resonance with the past, paying tribute to historical ideas that have illuminated our current understandings of interconnected systems of values and beliefs that underly the complementary artistic practices today.
In the words of pioneering Hungarian artist György Kepes (1906-2001) : “Our human nature is profoundly phototropic”. The exhibition is a reminder of the integral nature of light to human and more-than-human life, but also to the notion of light as a sensory environment within which we remain rooted, transfixed and nourished. The exhibiting artists take up these ideas in various formations, alluding to the physical, metaphorical and ecological implications of light. As an initial exhibition prototype, Afterglow is presented first at the Gales Gallery at York University in Toronto as it grows towards future touring exhibitions and symposia. The exhibition is integrated with a virtual Symposium that features exhibiting artists as well as International artists/theorists in conversation. Please proceed to our Eventbrite page for more details and registration [see below]. – Nina Czegledy, Joel Ong.
Afterglow Symposium Feb 6 [2025] 1-3pm [ET] Symposium Presenters: Andrea Polli, Jennifer Willet, Joel Ong, Karolina Halatek, Marton Orostz, Nina Czegledy and Raphael Arar.
If you’re in Toronto, you’re spoiled for choices. As for the rest of us, the Afterglow Symposium, as a hybrid event, offers an opportunity to hear from the artists.
One of the most intriguing (yes, it’s a pun) encryption stories (for me) is centuries old and concerns Mary Queen of Scots, from a February 10, 2023 article by Meilan Solly for Smithsonian Magazine, Note: Links have been removed,
Over the course of her 19 years in captivity, Mary, Queen of Scots, wrote thousands of letters to ambassadors, government officials, fellow monarchs and conspirators alike. Most of these missives had the same underlying goal: securing the deposed Scottish queen’s freedom. After losing her throne in 1567, Mary had fled to England, hoping to find refuge at her cousin Elizabeth I’s court. (Mary’s paternal grandmother, Margaret Tudor, was the sister of Elizabeth’s father, Henry VIII.) Instead, the English queen imprisoned Mary, keeping her under house arrest for nearly two decades before ordering her execution in 1587.
Mary’s letters have long fascinated scholars and the public, providing a glimpse into her relentless efforts to secure her release. But the former queen’s correspondence often raises more questions than it answers, in part because Mary took extensive steps to hide her messages from the prying eyes of Elizabeth’s spies. In addition to folding the pages with a technique known as letterlocking, she employed ciphers and codes of varying complexity.
More than 400 years after Mary’s death, a chance discovery by a trio of code breakers is offering new insights into the queen’s final years. As the researchers write in the journal Cryptologia, they originally decided to examine a cache of coded notes housed at the National Library of France as part of a broader push to “locate, digitize, transcribe, decipher and analyze” historic ciphers. Those pages turned out to be 57 of Mary’s encrypted letters, the majority of which were sent to Michel de Castelnau, the French ambassador to England, between 1578 and 1584. All but seven were previously thought to be lost.
Interspersed with a collection of early 16th-century Italian papers, the documents were written in mysterious symbols that offered no clues “as to their sender, recipients or date,” lead author George Lasry, a computer scientist and cryptographer based in Israel, tells Smithsonian magazine. It was only when the scholars spotted the word “Walsingham”—the last name of Elizabeth’s spymaster, Francis Walsingham—that they realized the letters’ significance.
“This was the ‘bingo moment,’” Lasry says. “We were very excited.”
Before getting too excited, the trio set out to confirm whether the letters were already known to historians. While they found copies of a few in British archives, “50 or so are new to historians—and a real gold mine for them,” says Lasry. In total, the letters contain 50,000 words of deciphered material.
…
Fascinating, non?
An October 10, 2024 news item on Nanowerk sheds light (more wordplay) on a contemporary approach to encryption,
Seoul National University(SNU) College of Engineering announced that a joint research team led by Professor Ki Tae Nam from the Department of Materials Science and Engineering at SNU and Professor Junil Choi from the Korea Advanced Institute of Science and Technology (KAIST) has developed a novel visible light communication encryption technology with high security using chiral nanoparticles.
Just as a lighthouse provides a guiding beam in the vast darkness of the sea, light-based information transmission has been a crucial means of communication throughout human history. Recently, next-generation communication technology based on visible light, which possesses high frequencies and linearity, has gained attention. It offers advantages such as integration with lighting systems and is free from the electromagnetic interference associated with conventional communication networks. With high security and fast transmission speeds, visible light communication is particularly suitable for local communication systems, especially in military operations involving vehicles, drones, and personnel.
In addition to intensity and wavelength (color), light can carry a vast amount of information through polarization. For instance, 3D movies use polarized filters to deliver two different polarized images to the viewer’s eyes, creating a sense of depth. Recently, efforts have been made to improve the security and performance of visible light communication, including the incorporation of technologies related to polarization, such as quantum information communication based on the superposition of polarization.
The SNU-KAIST joint research team focused on how light polarization can be significantly modulated through interaction with nanomaterials. In this study, they developed an innovative visible light communication encryption technology based on new materials. The core of this technology lies in chiral nanomaterials, which exhibit a symmetric structure when viewed in a mirror but do not overlap. These materials can significantly adjust the tilt of the polarization axis or its rotational properties. Having previously published two papers in 2018 and 2022 in the prestigious journal Nature on “the synthesis and optical device application of chiral nanoparticles with world-class polarization control performance,” the research team has now introduced a visible light communication encryption technology that cannot be replicated or intercepted without detailed information about the nanoparticles.
The chiral nanoparticles used in this technology are created by twisting their crystal structure using biomolecules like proteins and DNA, which possess natural chirality. The optical properties of these nanoparticles cannot be replicated without complete sequence information of the biomolecules used in their synthesis. Therefore, chiral nanoparticles function like fingerprints or unclonable keys in visible light communication, allowing only the receiver with the actual nanoparticles to correctly decode the information. This encryption technology is expected to have significant utility in secure point-to-point communication systems, such as those used in military operations involving drones.
Furthermore, the research team developed a spatiotemporal polarization control device capable of transmitting encrypted polarization information. By combining quantum nanorods, which efficiently emit polarized light, with nanowire materials that provide rotational properties to the light, they used 3D printing to fabricate a polarization control device with hundreds of micrometers of spatial resolution and nanoseconds of temporal resolution, allowing all polarization states to be represented without restriction. The transmitting unit can encrypt and transmit polarization information in a form suited to the polarization control properties of the nanoparticles using this device. This technology is expected to be the foundation for mass production of devices that can control spatiotemporal polarization without being constrained by form factor.
Professor Ki Tae Nam from SNU’s Department of Materials Science and Engineering said, “This research, which actively combines new material technologies with communication technologies, played a crucial role in developing the world’s first and only visible light communication encryption technology. We expect this technology to not only contribute to national defense but also be commercialized rapidly in industrial fields like display technology.” Professor Junil Choi from KAIST’s School of Electrical Engineering added, “This outstanding research result was achieved through joint efforts between material science and electrical engineering experts. In the future, we aim to further develop visible light communication technology based on nanoparticles to create communication systems that are fundamentally impossible to eavesdrop on.” Co-first author Jeong Hyun Han also stated, “We anticipate that this encryption system will act as a platform with great scalability and impact in the field of optical information transmission based on polarization.”
This research was supported by the Future Defense Technology Development Program of the Agency for Defense Development, the Basic Research Laboratory Program of the National Research Foundation of Korea, and private support from LG Display. The research outcome, which has been recognized for its significance, was published in the prestigious multidisciplinary journal Nature Communications on September 27 [2024].
Here’s a link to and a citation for the paper,
Spatiotemporally modulated full-polarized light emission for multiplexed optical encryption by Jiawei Lv, Jeong Hyun Han, Geonho Han, Seongmin An, Seung Ju Kim, Ryeong Myeong Kim, Jung‐El Ryu, Rena Oh, Hyuckjin Choi, In Han Ha, Yoon Ho Lee, Minje Kim, Gyeong-Su Park, Ho Won Jang, Junsang Doh, Junil Choi & Ki Tae Nam. Nature Communications volume 15, Article number: 8257 (2024) DOI: https://doi.org/10.1038/s41467-024-52358-7 Published: 27 September 2024
It seems like there’s never enough memory or enough speed where telecommunication is concerned. According to a July 24, 2023 news item on ScienceDaily announces a new way of transmitting large of amounts of data on earth and in outer space,
It is a scene many of us are familiar with: You’re working on your laptop at the local coffee shop with maybe a half dozen other laptop users — each of you is trying to load websites or stream high-definition videos, and all are craving more bandwidth. Now imagine that each of you had a dedicated wireless channel for communication that was hundreds of times faster than the Wi-Fi we use today, with hundreds of times more bandwidth. That dream may not be far off thanks to the development of metasurfaces — tiny engineered sheets that can reflect and otherwise direct light in desired ways.
In a paper published today [July 24, 2024] in the journal Nature Nanotechnology, a team of Caltech engineers reports building such a metasurface patterned with miniscule tunable antennas capable of reflecting an incoming beam of optical light to create many sidebands, or channels, of different optical frequencies.
“With these metasurfaces, we’ve been able to show that one beam of light comes in, and multiple beams of light go out, each with different optical frequencies and going in different directions,” says Harry Atwater, the Otis Booth Leadership Chair of the Division of Engineering and Applied Science, the Howard Hughes Professor of Applied Physics and Materials Science, and senior author on the new paper. “It’s acting like an entire array of communication channels. And we’ve found a way to do this for free-space signals rather than signals carried on an optical fiber.”
The work points to a promising route for the development of not only a new type of wireless communication channel but also potentially new range-finding technologies and even a novel way to relay larger amounts of data to and from space.
Co-lead author on the new paper Prachi Thureja, a graduate student in Atwater’s group, says to understand their work, first consider the word “metasurface.” The root, “meta,” comes from a Greek prefix meaning “beyond.” Metasurfaces are designed to go beyond what we can do with conventional bulky optical elements, such as camera or microscope lenses. The multilayer transistor-like devices are engineered with a carefully selected pattern of nanoscale antennas that can reflect, scatter, or otherwise control light. These flat devices can focus light, in the style of a lens, or reflect it, like a mirror, by strategically designing an array of nanoscale elements that modify the way that light responds.
Much previous work with metasurfaces has focused on creating passive devices that have a single light-directing functionality that is fixed in time. In contrast, Atwater’s group focuses on what are known as active metasurfaces. “Now we can apply an external stimulus, such as an array of different voltages, to these devices and tune between different passive functionalities,” says Jared Sisler, also a graduate student in Atwater’s lab and co-lead author on the paper.
In the latest work, the team describes what they call a space-time metasurface that can reflect light in specific directions and also at particular frequencies (a function of time, since frequency is defined as the number of waves that pass a point per second). This metasurface device, the core of which is just 120 microns wide and 120 microns long, operates in reflection mode at optical frequencies typically used for telecommunications, specifically at 1,530 nanometers. This is thousands of times higher than radio frequencies, which means there is much more available bandwidth.
At radio frequencies, electronics can easily steer a beam of light in different directions. This is routinely accomplished by the radar navigation devices used on airplanes. But there are currently no electronic devices that can do this at the much higher optical frequencies. Therefore, the researchers had to try something different, which was to change the properties of the antennas themselves.
Sisler and Thureja created their metasurface to consist of gold antennas, with an underlying electrically tunable semiconductor layer of indium tin oxide. By applying a known voltage profile across the device, they can locally modulate the density of electrons in the semiconductor layer below each antenna, changing its refractive index (the material’s light-bending ability). “By having the spatial configuration of different voltages across the device, we can then redirect the reflected light at specified angles in real time without the need to swap out any bulky components,” Thureja says.
“We have an incident laser hitting our metasurface at a certain frequency, and we modulate the antennas in time with a high-frequency voltage signal. This generates multiple new frequencies, or sidebands, that are carried by the incident laser light and can be used as high-data-rate channels for sending information. On top of this, we still have spatial control, meaning we can choose where each channel goes in space,” explains Sisler. “We are generating frequencies and steering them in space. That’s the space-time component of this metasurface.”
Looking toward the future
Beyond demonstrating that such a metasurface is capable of splitting and redirecting light at optical frequencies in free space (rather than in optical fibers), the team says the work points to several possible applications. These metasurfaces could be useful in LiDAR applications, the light equivalent of radar, where light is used to capture the depth information from a three-dimensional scene. The ultimate dream is to develop a “universal metasurface” that would create multiple optical channels, each carrying information in different directions in free space.
“If optical metasurfaces become a realizable technology that proliferates, a decade from now you’ll be able to sit in a Starbucks with a bunch of other people on their laptops and instead of each person getting a radio frequency Wi-Fi signal, they will get their own high-fidelity light beam signal,” says Atwater, who is also the director of the Liquid Sunlight Alliance at Caltech. “One metasurface will be able to beam a different frequency to each person.”
The group is collaborating with the Optical Communications Laboratory at JPL, which is working on using optical frequencies rather than radio frequency waves for communicating with space missions because this would enable the ability to send much more data at higher frequencies. “These devices would be perfect for what they’re doing,” says Sisler.
It’s unusual to see the same headline used to highlight research from two different teams released in such proximity, February 2024 and July 2024, respectively. Both of these are neuromorphic (brainlike) computing stories.
Researchers from the Leibniz Institute of Photonic Technology (Leibniz IPHT) and the Friedrich Schiller University in Jena, along with an international team, have developed a new technology that could significantly reduce the high energy demands of future AI systems. This innovation utilizes light for neuronal computing, inspired by the neural networks of the human brain. It promises not only more efficient data processing but also speeds many times faster than current methods, all while consuming considerably less energy. Published in the prestigious journal „Advanced Science,“ their work introduces new avenues for environmentally friendly AI applications, as well as advancements in computerless diagnostics and intelligent microscopy.
Artificial intelligence (AI) is pivotal in advancing biotechnology and medical procedures, ranging from cancer diagnostics to the creation of new antibiotics. However, the ecological footprint of large-scale AI systems is substantial. For instance, training extensive language models like ChatGPT-3 requires several gigawatt-hours of energy—enough to power an average nuclear power plant at full capacity for several hours.
Prof. Mario Chemnitz, new Junior Professor of Intelligent Photonic SystemsExternal link at Friedrich Schiller University Jena, and Dr Bennet Fischer from Leibniz IPHT in Jena, in collaboration with their international team, have devised an innovative method to develop potentially energy-efficient computing systems that forego the need for extensive electronic infrastructure. They harness the unique interactions of light waves within optical fibers to forge an advanced artificial learning system.
A single fiber instead of thousands of components
Unlike traditional systems that rely on computer chips containing thousands of electronic components, their system uses a single optical fiber. This fiber is capable of performing the tasks of various neural networks—at the speed of light. “We utilize a single optical fiber to mimic the computational power of numerous neural networks,“ Mario Chemnitz, who is also leader of the “Smart Photonics“ junior research group at Leibniz IPHT, explains. “By leveraging the unique physical properties of light, this system will enable the rapid and efficient processing of vast amounts of data in the future.“
Delving into the mechanics reveals how information transmission occurs through the mixing of light frequencies: Data—whether pixel values from images or frequency components of an audio track—are encoded onto the color channels of ultrashort light pulses. These pulses carry the information through the fiber, undergoing various combinations, amplifications, or attenuations. The emergence of new color combinations at the fiber’s output enables the prediction of data types or contexts. For example, specific color channels can indicate visible objects in images or signs of illness in a voice.
A prime example of machine learning is identifying different numbers from thousands of handwritten characters. Mario Chemnitz, Bennet Fischer, and their colleagues from the Institut National de la Recherche Scientifique (INRS) in Québec utilized their technique to encode images of handwritten digits onto light signals and classify them via the optical fiber. The alteration in color composition at the fiber’s end forms a unique color spectrum—a „fingerprint“ for each digit. Following training, the system can analyze and recognize new handwriting digits with significantly reduced energy consumption.
System recognizes COVID-19 from voice samples
“In simpler terms, pixel values are converted into varying intensities of primary colors—more red or less blue, for instance,“ Mario Chemnitz details. “Within the fiber, these primary colors blend to create the full spectrum of the rainbow. The shade of our mixed purple, for example, reveals much about the data processed by our system.“
The team has also successfully applied this method in a pilot study to diagnose COVID-19 infections using voice samples, achieving a detection rate that surpasses the best digital systems to date.
“We are the first to demonstrate that such a vibrant interplay of light waves in optical fibers can directly classify complex information without any additional intelligent software,“ Mario Chemnitz states.
Since December 2023, Mario Chemnitz has held the position of Junior Professor of Intelligent Photonic Systems at Friedrich Schiller University Jena. Following his return from INRS in Canada in 2022, where he served as a postdoc, Chemnitz has been leading an international team at Leibniz IPHT in Jena. With Nexus funding support from the Carl Zeiss Foundation, their research focuses on exploring the potentials of non-linear optics. Their goal is to develop computer-free intelligent sensor systems and microscopes, as well as techniques for green computing.
Here’s a link to and a citation for the paper,
Neuromorphic Computing via Fission-based Broadband Frequency Generation by Bennet Fischer, Mario Chemnitz, Yi Zhu, Nicolas Perron, Piotr Roztocki, Benjamin MacLellan, Luigi Di Lauro, A. Aadhi, Cristina Rimoldi, Tiago H. Falk, Roberto Morandotti. Advanced Science Volume 10, Issue 35 December 15, 2023 2303835 DOI: https://doi.org/10.1002/advs.202303835. First published: 02 October 2023
Scientists propose a new way of implementing a neural network with an optical system which could make machine learning more sustainable in the future. The researchers at the Max Planck Institute for the Science of Light have published their new method in Nature Physics, demonstrating a method much simpler than previous approaches.
Machine learning and artificial intelligence are becoming increasingly widespread with applications ranging from computer vision to text generation, as demonstrated by ChatGPT. However, these complex tasks require increasingly complex neural networks; some with many billion parameters. This rapid growth of neural network size has put the technologies on an unsustainable path due to their exponentially growing energy consumption and training times. For instance, it is estimated that training GPT-3 consumed more than 1,000 MWh of energy, which amounts to the daily electrical energy consumption of a small town. This trend has created a need for faster, more energy- and cost-efficient alternatives, sparking the rapidly developing field of neuromorphic computing. The aim of this field is to replace the neural networks on our digital computers with physical neural networks. These are engineered to perform the required mathematical operations physically in a potentially faster and more energy-efficient way.
Optics and photonics are particularly promising platforms for neuromorphic computing since energy consumption can be kept to a minimum. Computations can be performed in parallel at very high speeds only limited by the speed of light. However, so far, there have been two significant challenges: Firstly, realizing the necessary complex mathematical computations requires high laser powers. Secondly, the lack of an efficient general training method for such physical neural networks.
Both challenges can be overcome with the new method proposed by Clara Wanjura and Florian Marquardt from the Max Planck Institute for the Science of Light in their new article in Nature Physics. “Normally, the data input is imprinted on the light field. However, in our new methods we propose to imprint the input by changing the light transmission,” explains Florian Marquardt, Director at the Institute. In this way, the input signal can be processed in an arbitrary fashion. This is true even though the light field itself behaves in the simplest way possible in which waves interfere without otherwise influencing each other. Therefore, their approach allows one to avoid complicated physical interactions to realize the required mathematical functions which would otherwise require high-power light fields. Evaluating and training this physical neural network would then become very straightforward: “It would really be as simple as sending light through the system and observing the transmitted light. This lets us evaluate the output of the network. At the same time, this allows one to measure all relevant information for the training”, says Clara Wanjura, the first author of the study. The authors demonstrated in simulations that their approach can be used to perform image classification tasks with the same accuracy as digital neural networks.
In the future, the authors are planning to collaborate with experimental groups to explore the implementation of their method. Since their proposal significantly relaxes the experimental requirements, it can be applied to many physically very different systems. This opens up new possibilities for neuromorphic devices allowing physical training over a broad range of platforms.
XPANCEO, a deep tech company developing the first smart contact lenses with XR vision, health monitoring, and content surfing features, in collaboration with the Nobel laureate Konstantin S. Novoselov (National University of Singapore, University of Manchester) and professor Luis Martin-Moreno (Instituto de Nanociencia y Materiales de Aragon), has announced in Nature Communications a groundbreaking discovery of new properties of rhenium diselenide and rhenium disulfide, enabling novel mode of light-matter interaction with huge potential for integrated photonics, healthcare, and AR. Rhenium disulfide and rhenium diselenide are layered materials belonging to the family of graphene-like materials. Absorption and refraction in these materials have different principal directions, implying six degrees of freedom instead of a maximum of three in classical materials. As a result, rhenium disulfide and rhenium diselenide by themselves allow controlling the light propagation direction without any technological steps required for traditional materials like silicon and titanium dioxide.
The origin of such surprising light-matter interaction of ReS2 and ReSe2 with light is due to the specific symmetry breaking observed in these materials. Symmetry plays a huge role in nature, human life, and material science. For example, almost all living things are built symmetrically. Therefore, in ancient times symmetry was also called harmony, as it was associated with beauty. Physical laws are also closely related to symmetry, such as the laws of conservation of energy and momentum. Violation of symmetry leads to the appearance of new physical effects and radical changes in the properties of materials. In particular, the water-ice phase transition is a consequence of a decrease in the degree of symmetry. In the case of ReS2 and ReSe2, the crystal lattice has the lowest possible degree of symmetry, which leads to the rotation of optical axes – directions of symmetry of optical properties of the material, which was previously observed only for organic materials. As a result, these materials make possible to control the direction of light by changing the wavelength, which opens a unique way for light manipulation in next-generation devices and applications.
“The discovery of unique properties in anisotropic materials is revolutionizing the fields of nanophotonics and optoelectronics, presenting exciting possibilities. These materials serve as a versatile platform for the advancement of optical devices, such as wavelength-switchable metamaterials, metasurfaces, and waveguides. Among the promising applications is the development of highly efficient biochemical sensors. These sensors have the potential to outperform existing analogs in terms of both sensitivity and cost efficiency. For example, they are anticipated to significantly reduce the expenses associated with hospital blood testing equipment, which is currently quite costly, potentially by several orders of magnitude. This will also allow the detection of dangerous diseases and viruses, such as cancer or COVID, at earlier stages,” says Dr. Valentyn S. Volkov, co-founder and scientific partner at XPANCEO, a scientist with an h-Index of 38 and over 8000 citations in leading international publications.
Beyond the healthcare industry, these novel properties of graphene-like materials can find applications in artificial intelligence and machine learning, facilitating the development of photonic circuits to create a fast and powerful computer suitable for machine learning tasks. A computer based on photonic circuits is a superior solution, transmitting more information per unit of time, and unlike electric currents, photons (light beams) flow across one another without interacting. Furthermore, the new material properties can be utilized in producing smart optics, such as contact lenses or glasses, specifically for advancing AR [augmented reality] features. Leveraging these properties will enhance image coloration and adapt images for individuals with impaired color perception, enabling them to see the full spectrum of colors.
Here’s a link to and a citation for the paper,
Wandering principal optical axes in van der Waals triclinic materials by Georgy A. Ermolaev, Kirill V. Voronin, Adilet N. Toksumakov, Dmitriy V. Grudinin, Ilia M. Fradkin, Arslan Mazitov, Aleksandr S. Slavich, Mikhail K. Tatmyshevskiy, Dmitry I. Yakubovsky, Valentin R. Solovey, Roman V. Kirtaev, Sergey M. Novikov, Elena S. Zhukova, Ivan Kruglov, Andrey A. Vyshnevyy, Denis G. Baranov, Davit A. Ghazaryan, Aleksey V. Arsenin, Luis Martin-Moreno, Valentyn S. Volkov & Kostya S. Novoselov. Nature Communications volume 15, Article number: 1552 (2024) DOI: https://doi.org/10.1038/s41467-024-45266-3 Published: 06 March 2024
Unfortunately, there isn’t a punch line but I appreciate the effort to inject a little lightness into the description of a fairly technical achievement, from a February 12, 2024 news item on Nanowerk, Note: A link has been removed,
Electrons carry electrical energy, while vibrational energy is carried by phonons. Understanding how they interact with each other in certain materials, like in a sandwich of two graphene layers, will have implications for future optoelectronic devices.
Electrons carry electrical energy, while vibrational energy is carried by phonons. Understanding how they interact with each other in certain materials, like in a sandwich of two graphene layers, will have implications for future optoelectronic devices. Recent work has revealed that graphene layers twisted relative to each other by a small ‘magic angle’ can act as perfect insulator or superconductor. But the physics of the electron-phonon interactions are a mystery. As part of a worldwide international collaboration, TU/e researcher Klaas-Jan Tielrooij has led a study on electron-phonon interactions in graphene layers. And they have made a startling discovery.
What did the electron say to the phonon between two layers of graphene?
This might sound like the start of a physics meme with a hilarious punchline to follow. But that’s not the case according to Klaas-Jan Tielrooij. He’s an associate professor at the Department of Applied Physics and Science Education at TU/e and the research lead of the new work published in Science Advances.
“We sought to understand how electrons and phonons ‘talk’ to each other within two twisted graphene layers,” says Tielrooij.
Electrons are the well-known charge and energy carriers associated with electricity, while a phonon is linked to the emergence of vibrations between atoms in an atomic crystal.
“Phonons aren’t particles like electrons though, they’re a quasiparticle. Yet, their interaction with electrons in certain materials and how they affect energy loss in electrons has been a mystery for some time,” notes Tielrooij.
But why would it be interesting to learn more about electron-phonon interactions? “These interactions can have a major effect on the electronic and optoelectronic properties of devices, made from materials like graphene, which we are going to see more of in the future.”
Twistronics: Breakthrough of the Year 2018
Tielrooij and his collaborators, who are based around the world in Spain, Germany, Japan, and the US, decided to study electron-phonon interactions in a very particular case – within two layers of graphene where the layers are ever-so-slightly misaligned.
Graphene is a two-dimensional layer of carbon atoms arranged in a honeycomb lattice that has several impressive properties such as high electrical conductivity, high flexibility, and high thermal conductivity, and it is also nearly transparent.
Back in 2018, the Physics World Breakthrough of the Year award went to Pablo Jarillo-Herrero and colleagues at MIT [Massachusetts Institute of Technology] for their pioneering work on twistronics, where adjacent layers of graphene are rotated very slightly relative to each other to change the electronic properties of the graphene.
Twist and astound!
“Depending on how the layers of graphene are rotated and doped with electrons, contrasting outcomes are possible. For certain dopings, the layers act as an insulator, which prevents the movement of electrons. For other doping, the material behaves as a superconductor – a material with zero resistance that allows the dissipation-less movement of electrons,” says Tielrooij.
Better known as twisted bilayer graphene, these outcomes occur at the so-called magic angle of misalignment, which is just over one degree of rotation. “The misalignment between the layers is tiny, but the possibility for a superconductor or an insulator is an astounding result.”
How electrons lose energy
For their study, Tielrooij and the team wanted to learn more about how electrons lose energy in magic-angle twisted bilayer graphene, or MATBG for short.
To achieve this, they used a material consisting of two sheets of monolayer graphene (each 0.3 nanometers thick), placed on top of each other, and misaligned relative to each other by about one degree.
Then using two optoelectronic measurement techniques, the researchers were able to probe the electron-phonon interactions in detail, and they made some staggering discoveries.
“We observed that the energy vanishes very quickly in the MATBG – it occurs on the picosecond timescale, which is one-millionth of one-millionth of a second!” says Tielrooij.
This observation is much faster than for the case of a single layer of graphene, especially at ultracold temperatures (specifically below -73 degrees Celsius). “At these temperatures, it’s very difficult for electrons to lose energy to phonons, yet it happens in the MATBG.”
Why electrons lose energy
So, why are the electrons losing the energy so quickly through interaction with the phonons? Well, it turns out the researchers have uncovered a whole new physical process.
“The strong electron-phonon interaction is a completely new physical process and involves so-called electron-phonon Umklapp scattering,” adds Hiroaki Ishizuka from Tokyo Institute of Technology in Japan, who developed the theoretical understanding of this process together with Leonid Levitov from Massachusetts Institute of Technology in the US.
Umklapp scattering between phonons is a process that often affects heat transfer in materials, because it enables relatively large amounts of momentum to be transferred between phonons.
“We see the effects of phonon-phonon Umklapp scattering all the time as it affects the ability for (non-metallic) materials at room temperature to conduct heat. Just think of an insulating material on the handle of a pot for example,” says Ishizuka. “However, electron-phonon Umklapp scattering is rare. Here though we have observed for the first time how electrons and phonons interact via Umklapp scattering to dissipate electron energy.”
Challenges solved together
Tielrooij and collaborators may have completed most of the work while he was based in Spain at the Catalan Institute of Nanoscience and Nanotechnology (ICN2), but as Tielrooij notes. “The international collaboration proved pivotal to making this discovery.”
So, how did all the collaborators contribute to the research? Tielrooij: “First, we needed advanced fabrication techniques to make the MATBG samples. But we also needed a deep theoretical understanding of what’s happening in the samples. Added to that, ultrafast optoelectronic measurement setups were required to measure what’s happening in the samples too.”
Tielrooij and the team received the magic-angle twisted samples from Dmitri Efetov’s group at Ludwig-Maximilians-Universität in Munich, who were the first group in Europe able to make such samples and who also performed photomixing measurements, while theoretical work at MIT in the US and at Tokyo Institute of Technology in Japan proved crucial to the success of the research.
At ICN2, Tielrooij and his team members Jake Mehew and Alexander Block used cutting-edge equipment particularly time-resolved photovoltage microscopy to perform their measurements of electron-phonon dynamics in the samples.
The future
So, what does the future look like for these materials then? According to Tielrooij, don’t expect anything too soon.
“As the material is only being studied for a few years, we’re still some way from seeing magic-angle twisted bilayer graphene having an impact on society.”
But there is a great deal to be explored about energy loss in the material.
“Future discoveries could have implications for charge transport dynamics, which could have implications for future ultrafast optoelectronics devices,” says Tielrooij. “In particular, they would be very useful at low temperatures, so that makes the material suitable for space and quantum applications.”
The research from Tielrooij and the international team is a real breakthrough when it comes to how electrons and phonons interact with each other.
But we’ll have to wait a little longer to fully understand the consequences of what the electron said to the phonon in the graphene sandwich.
Illustration showing the control of energy relaxation with twist angle. Image: Authors
Here’s a link to and a citation for the paper,
Ultrafast Umklapp-assisted electron-phonon cooling in magic-angle twisted bilayer graphene by Jake Dudley Mehew, Rafael Luque Merino, Hiroaki Ishizuka, Alexander Block, Jaime Díez Mérida, Andrés Díez Carlón, Kenji Watanabe, Takashi Taniguchi, Leonid S. Levitov, Dmitri K. Efetov, and Klaas-Jan Tielrooij. Science Advances 9 Feb 2024 Vol 10, Issue 6 DOI: 10.1126/sciadv.adj1361
Apparently, the Morpho butterfly (or blue morpho butterfly) could inspire more balanced lighting, from an October 12, 2023 news item on phys.org,
As you watch Morpho butterflies wobble in flight, shimmering in vivid blue color, you’re witnessing an uncommon form of structural color that researchers are only beginning to use in lighting technologies such as optical diffusers. Furthermore, imparting a self-cleaning capability to such diffusers would minimize soiling and staining and maximize practical utility.
Now, in a study recently published in Advanced Optical Materials, researchers at Osaka University have developed a water-repelling nanostructured light diffuser that surpasses the functionality of other common diffusers. This work might help solve common lighting dilemmas in modern technologies.
…
Caption: Design and diffused light for the anisotropic (left) and isotropic (right) Morpho-type diffusers. It has high optical functionalities and anti-fouling properties, which until now have not been realized in one device. Credit: K.Yamashita, A.Saito
Standard lighting can eventually become tiring because it’s unevenly illuminating. Thus, many display technologies use optical diffusers to make the light output more uniform. However, conventional optical diffusers reduce the light output, don’t work well for all emitted colors, or require special effort to clean. Morpho butterflies are an inspiration for improved optical diffusers. Their randomly arranged multilayer architecture enables structural color: in this case, selective reflection of blue light over a ≥±40° angle from the direction of illumination. The goal of the present work is to use this inspiration from nature to design a simplified optical diffuser that has both high transmittance and wide angular spread, works for a range of colors without dispersion, cleans by a simple water rinse, and can be shaped with standard nanofabrication tools.
“We create two-dimensional nanopatterns—in common transparent polydimethylsiloxane elastomer—of binary height yet random width, and the two surfaces have different structural scales,” explains Kazuma Yamashita, lead author of the study. “Thus, we report an effective optical diffuser for short- and long-wavelength light.”
The researchers tailored the patterns of the diffuser surfaces to optimize the performance for blue and red light, and their self-cleaning properties. The experimentally measured light transmittance was >93% over the entire visible light spectrum, and the light diffusion was substantial and could be controlled into anisotropic shape: 78° in the x-direction and 16° in the y-direction (similar to values calculated by simulations). Furthermore, the surfaces both strongly repelled water in contact angle and self-cleaning experiments.
“Applying protective cover glass layers on either side of the optical diffuser largely maintains the optical properties, yet protects against scratching,” says Akira Saito, senior author. “The glass minimizes the need for careful handling, and indicates our technology’s utility to daylight-harvesting windows.”
This work emphasizes that studying the natural world can provide insights for improved everyday devices; in this case, lighting technologies for visual displays. The fact that the diffuser consists of a cheap material that essentially cleans itself and can be easily shaped with common tools might inspire other researchers to apply the results of this work to electronics and many other fields.
Caption: Physicists at Stevens Institute of Technology use a 350-year-old theorem that explains the workings of pendulums and planets to reveal new properties of light waves. Credit: Stevens Institute of Technology
An August 21, 2023 news item on phys.org revisits a 350-year old theorem, Note: Links have been removed,
Since the 17th century, when Isaac Newton and Christiaan Huygens first debated the nature of light, scientists have been puzzling over whether light is best viewed as a wave or a particle—or perhaps, at the quantum level, even both at once. Now, researchers at Stevens Institute of Technology have revealed a new connection between the two perspectives, using a 350-year-old mechanical theorem—ordinarily used to describe the movement of large, physical objects like pendulums and planets—to explain some of the most complex behaviors of light waves.
The work, led by Xiaofeng Qian, assistant professor of physics at Stevens and reported in the August 17 [2023] online issue of Physical Review Research, also proves for the first time that a light wave’s degree of non-quantum entanglement exists in a direct and complementary relationship with its degree of polarization. As one rises, the other falls, enabling the level of entanglement to be inferred directly from the level of polarization, and vice versa. This means that hard-to-measure optical properties such as amplitudes, phases and correlations—perhaps even these of quantum wave systems—can be deduced from something a lot easier to measure: light intensity.
“We’ve known for over a century that light sometimes behaves like a wave, and sometimes like a particle, but reconciling those two frameworks has proven extremely difficult,” said Qian “Our work doesn’t solve that problem — but it does show that there are profound connections between wave and particle concepts not just at the quantum level, but at the level of classical light-waves and point-mass systems.”
Qian’s team used a mechanical theorem, originally developed by Huygens in a 1673 book on pendulums, that explains how the energy required to rotate an object varies depending on the object’s mass and the axis around which it turns. “This is a well-established mechanical theorem that explains the workings of physical systems like clocks or prosthetic limbs,” Qian explained. “But we were able to show that it can offer new insights into how light works, too.”
This 350-year-old theorem describes relationships between masses and their rotational momentum, so how could it be applied to light where there is no mass to measure? Qian’s team interpreted the intensity of a light as the equivalent of a physical object’s mass, then mapped those measurements onto a coordinate system that could be interpreted using Huygens’ mechanical theorem. “Essentially, we found a way to translate an optical system so we could visualize it as a mechanical system, then describe it using well-established physical equations,” explained Qian.
Once the team visualized a light wave as part of a mechanical system, new connections between the wave’s properties immediately became apparent — including the fact that entanglement and polarization stood in a clear relationship with one another.
“This was something that hadn’t been shown before, but that becomes very clear once you map light’s properties onto a mechanical system,” said Qian. “What was once abstract becomes concrete: using mechanical equations, you can literally measure the distance between ‘center of mass’ and other mechanical points to show how different properties of light relate to one another.”
Clarifying these relationships could have important practical implications, allowing subtle and hard-to-measure properties of optical systems — or even quantum systems — to be deduced from simpler and more robust measurements of light intensity, Qian explained. More speculatively, the team’s findings suggest the possibility of using mechanical systems to simulate and better-understand the strange and complex behaviors of quantum wave systems.
“That still lies ahead of us, but with this first study we’ve shown clearly that by applying mechanical concepts, it’s possible to understand optical systems in an entirely new way,” Qian said. “Ultimately, this research is helping to simplify the way we understand the world, by allowing us to recognize the intrinsic underlying connections between apparently unrelated physical laws.”
Researchers have created a small device that ‘sees’ and creates memories in a similar way to humans, in a promising step towards one day having applications that can make rapid, complex decisions such as in self-driving cars.
The neuromorphic invention is a single chip enabled by a sensing element, doped indium oxide, that’s thousands of times thinner than a human hair and requires no external parts to operate.
RMIT University engineers in Australia led the work, with contributions from researchers at Deakin University and the University of Melbourne.
The team’s research demonstrates a working device that captures, processes and stores visual information. With precise engineering of the doped indium oxide, the device mimics a human eye’s ability to capture light, pre-packages and transmits information like an optical nerve, and stores and classifies it in a memory system like the way our brains can.
Collectively, these functions could enable ultra-fast decision making, the team says.
Team leader Professor Sumeet Walia said the new device can perform all necessary functions – sensing, creating and processing information, and retaining memories – rather than relying on external energy-intensive computation, which prevents real-time decision making.
“Performing all of these functions on one small device had proven to be a big challenge until now,” said Walia from RMIT’s School of Engineering.
“We’ve made real-time decision making a possibility with our invention, because it doesn’t need to process large amounts of irrelevant data and it’s not being slowed down by data transfer to separate processors.”
What did the team achieve and how does the technology work?
The new device was able to demonstrate an ability to retain information for longer periods of time, compared to previously reported devices, without the need for frequent electrical signals to refresh the memory. This ability significantly reduces energy consumption and enhances the device’s performance.
Their findings and analysis are published in Advanced Functional Materials.
First author and RMIT PhD researcher Aishani Mazumder said the human brain used analog processing, which allowed it to process information quickly and efficiently using minimal energy.
“By contrast, digital processing is energy and carbon intensive, and inhibits rapid information gathering and processing,” she said.
“Neuromorphic vision systems are designed to use similar analog processing to the human brain, which can greatly reduce the amount of energy needed to perform complex visual tasks compared with today’s technologies
What are the potential applications?
The team used ultraviolet light as part of their experiments, and are working to expand this technology even further for visible and infrared light – with many possible applications such as bionic vision, autonomous operations in dangerous environments, shelf-life assessments of food and advanced forensics.
“Imagine a self-driving car that can see and recognise objects on the road in the same way that a human driver can or being able to able to rapidly detect and track space junk. This would be possible with neuromorphic vision technology.”
Walia said neuromorphic systems could adapt to new situations over time, becoming more efficient with more experience.
“Traditional computer vision systems – which cannot be miniaturised like neuromorphic technology – are typically programmed with specific rules and can’t adapt as easily,” he said.
“Neuromorphic robots have the potential to run autonomously for long periods, in dangerous situations where workers are exposed to possible cave-ins, explosions and toxic air.”
The human eye has a single retina that captures an entire image, which is then processed by the brain to identify objects, colours and other visual features.
The team’s device mimicked the retina’s capabilities by using single-element image sensors that capture, store and process visual information on one platform, Walia said.
“The human eye is exceptionally adept at responding to changes in the surrounding environment in a faster and much more efficient way than cameras and computers currently can,” he said.
“Taking inspiration from the eye, we have been working for several years on creating a camera that possesses similar abilities, through the process of neuromorphic engineering.”
A June 5, 2023 news item on Nanowerk announced a paper which reviews the state-of-the-art of optical memristors, Note: Links have been removed,
AI, machine learning, and ChatGPT may be relatively new buzzwords in the public domain, but developing a computer that functions like the human brain and nervous system – both hardware and software combined – has been a decades-long challenge. Engineers at the University of Pittsburgh are today exploring how optical “memristors” may be a key to developing neuromorphic computing.
Resistors with memory, or memristors, have already demonstrated their versatility in electronics, with applications as computational circuit elements in neuromorphic computing and compact memory elements in high-density data storage. Their unique design has paved the way for in-memory computing and captured significant interest from scientists and engineers alike.
A new review article published in Nature Photonics (“Integrated Optical Memristors”), sheds light on the evolution of this technology—and the work that still needs to be done for it to reach its full potential. Led by Nathan Youngblood, assistant professor of electrical and computer engineering at the University of Pittsburgh Swanson School of Engineering, the article explores the potential of optical devices which are analogs of electronic memristors. This new class of device could play a major role in revolutionizing high-bandwidth neuromorphic computing, machine learning hardware, and artificial intelligence in the optical domain.
“Researchers are truly captivated by optical memristors because of their incredible potential in high-bandwidth neuromorphic computing, machine learning hardware, and artificial intelligence,” explained Youngblood. “Imagine merging the incredible advantages of optics with local information processing. It’s like opening the door to a whole new realm of technological possibilities that were previously unimaginable.”
The review article presents a comprehensive overview of recent progress in this emerging field of photonic integrated circuits. It explores the current state-of-the-art and highlights the potential applications of optical memristors, which combine the benefits of ultrafast, high-bandwidth optical communication with local information processing. However, scalability emerged as the most pressing issue that future research should address.
“Scaling up in-memory or neuromorphic computing in the optical domain is a huge challenge. Having a technology that is fast, compact, and efficient makes scaling more achievable and would represent a huge step forward,” explained Youngblood.
“One example of the limitations is that if you were to take phase change materials, which currently have the highest storage density for optical memory, and try to implement a relatively simplistic neural network on-chip, it would take a wafer the size of a laptop to fit all the memory cells needed,” he continued. “Size matters for photonics, and we need to find a way to improve the storage density, energy efficiency, and programming speed to do useful computing at useful scales.”
Using Light to Revolutionize Computing
Optical memristors can revolutionize computing and information processing across several applications. They can enable active trimming of photonic integrated circuits (PICs), allowing for on-chip optical systems to be adjusted and reprogrammed as needed without continuously consuming power. They also offer high-speed data storage and retrieval, promising to accelerate processing, reduce energy consumption, and enable parallel processing.
Optical memristors can even be used for artificial synapses and brain-inspired architectures. Dynamic memristors with nonvolatile storage and nonlinear output replicate the long-term plasticity of synapses in the brain and pave the way for spiking integrate-and-fire computing architectures.
Research to scale up and improve optical memristor technology could unlock unprecedented possibilities for high-bandwidth neuromorphic computing, machine learning hardware, and artificial intelligence.
“We looked at a lot of different technologies. The thing we noticed is that we’re still far away from the target of an ideal optical memristor–something that is compact, efficient, fast, and changes the optical properties in a significant manner,” Youngblood said. “We’re still searching for a material or a device that actually meets all these criteria in a single technology in order for it to drive the field forward.”
The publication of “Integrated Optical Memristors” (DOI: 10.1038/s41566-023-01217-w) was published in Nature Photonics and is coauthored by senior author Harish Bhaskaran at the University of Oxford, Wolfram Pernice at Heidelberg University, and Carlos Ríos at the University of Maryland.
Despite including that final paragraph, I’m also providing a link to and a citation for the paper,
Integrated optical memristors by Nathan Youngblood, Carlos A. Ríos Ocampo, Wolfram H. P. Pernice & Harish Bhaskaran. Nature Photonics volume 17, pages 561–572 (2023) DOI: https://doi.org/10.1038/s41566-023-01217-w Published online: 29 May 2023 Issue Date: July 2023
