August, 2023 - Technion - Israel Institute of Technology

Technion - Israel Institute of Technology > Articles by: 2023 > August

“I have a notebook where I have been drawing for the past year during any free time – like breaks, or in the morning. I draw with a pen, so you can’t erase it. My art is a place for imperfection. You can’t erase and go back, and that’s something that released me from the desire for perfection. It gave room to develop and make mistakes. I am glad that at the Technion, which is characterized by the pursuit of excellence and perfection, there is also a place for the imperfect. I never thought that the drawings from the notebook would be displayed on such a public platform. It’s very exciting that it happened, and more so in Ullmann.”

These remarks were made by Ofek Zur, a student in the faculties of physics and electrical and computer engineering, at the opening of a new exhibition at the Technion: “Charging Stations”. The exhibition opened in the Ullmann building, where students from all faculties study during their first year at the Technion.

Curator Valeria Geselev explained that “the exhibition was born from a perception of the academic campus as a public space. The Technion is a kind of city, and like a city, here too there is a tension between belonging and anonymity, between closeness and strangeness, and the question arises as to whose place this really is. The exhibitions in the Ullmann building are designed to strengthen the students’ feelings of belonging and ownership and to create collaborations and conceptual support between students, members of the academic staff, administrative staff and graduates.”

The exhibition began with a “call” that invited the students on campus to participate in the project. in the end, 14 students were selected from a variety of faculties, some in undergraduate studies and others in advanced degrees: Yoav Edelstein (physics), Ohad Aridor (materials science and engineering), Itay Chen (medicine), Joelle Khriesh (biomedical engineering), Mark Levit (physics), Sonia Metelitsa (mathematics), Sharon Nagosa (architecture and town planning), Tamar Nix (architecture and town planning), Johanna Sklar (materials science and engineering), Caroleen Ataria (data and decision sciences), Ofek Zur (physics and electrical and computer engineering), Aseel Qub (materials science and engineering), Alis Kalman (biology), and Alon Romano (architecture and town planning).

The executive committee of the exhibition includes Senior Executive Vice President Prof. Oded Rabinovitch, Dean of Students; Prof. Ayelet Fishman, Dean of Undergraduate Studies; Prof. Hossam Haick and representatives of the Office of the Dean of Students and the Department for Certification Studies. Prof. Rabinovitch said at the exhibition’s opening, “the entry of art into the Ullmann Building, and the Technion in general, invites us to an expression, a multidimensional experience, and a complement to the intellect, which is the central aspect of studies at the Technion. The Ullmann building is the Technion’s melting pot, the place that shapes Technion graduates during their studies. This is already the fourth exhibition in the building and today it seems natural to us, but none of this would have happened without the initiative of the Academic Secretary for Undergraduate Studies, Dr. Efrat Nativ Ronen. and the curator, Valeria Geselev, and without cooperation between the various departments.”

Dean of Students Prof. Ayelet Fishman said that “as dean, it is very important to me that our students feel that the Technion is a home, and there is no home without pictures, without a personal touch, and without the warmth of a home. This exhibition presents a wide variety of creators and subjects and reminds us that we all love people, and that art speaks to us all.”

Dean of Undergraduate Studies, Prof. Hossam Haick, said that “the exhibitions in Ullmann have given this building a new heart. The people who work in this building have developed an enormous attention for students and are partners in these artistic projects, which transmit creativity inside but also outwards, throughout the campus, and provide us an opportunity to observe and feel our humanity.”

Administrative Affairs Assistant to Undergraduate Studies Reuma Schwartz managed the project on behalf of the Technion. She said that “the project was born out of a desire to help create social relationships between male and female students, to strengthen the relationship between the academic and administrative staff, to create a supportive community at the Technion, to give a platform for the expression of creative students and provide them a unique student experience. In the end, the establishment of the project was a ‘charging station’ for all its partners. Following the exhibition, and thanks to the fruitful cooperation between the Office of the Dean of Students and the Certification Studies Department, there will be additional activities for all students and faculty: artist workshops, interactive activities and more.”

The “Charging Station” is a permanent exhibition that spans five different floors of the Ullmann building: between classrooms, the staircases, and the advisory offices. The exhibition is accessible during all campus operating hours. You can view the exhibition map here.

In the photos:

Reuma Schwartz and behind her is the work of Tamar Nix, “Cloudburst”

Ribbon cutting. From right to left: Dean of Students Prof. Ayelet Fishman, Senior Executive Vice President Prof. Oded Rabinovitch, and Dean of Undergraduate Studies Prof. Hossam Haick

גזירת הסרט. מימין לשמאל: דיקנית הסטודנטים פרופ' אילת פישמן, המשנה הבכיר לנשיא הטכניון פרופ' עודד רבינוביץ' ודיקן לימודי הסמכה פרופ' חוסאם חאיק

Executive Vice President of the Technion Dr. Rafi Aviram

Efrat (Efi) Barkai Goral, the “Israeli Hatikvah” at the Technion

Curator of the exhibit Valeria Geselev (right) with student Johanna Sklar and Sklar’s creation “Blue Bay”

Student Sharon Nagosa and her creation “Family Vacation”

Student Joelle Khriesh and her creation “I’m here for you”

Student Ofek Zur

Photos: Yair Schwartz

For more information and collaborations: Project Manager Reuma Schwartz Reuma@technion.ac.il

The Harvey Prize, the most prestigious award bestowed by the Technion – Israel Institute of Technology, will be presented this year in two fields:

In Science and Technology, the prize will be awarded to Professor Emerita Helen Quinn from SLAC National Accelerator Laboratory. In the field of Human Health, the prize will be awarded to Professors Katalin Karikó and Drew Weissman from the University of Pennsylvania, and to Professor Pieter R. Cullis from the University of British Columbia.

Human Health

The research of Profs. Karikó, Weissman and Cullis enabled the rapid development and delivery of effective COVID-19 vaccines. Their fundamental discoveries revolutionized the delivery of effective and safe vaccines, bringing about new types of therapeutics, as well as potential genetic therapies that contributed to the well-being of humans.

Professor Karikó is a biochemist focused on RNA biology. She earned her Ph.D. from the University of Szeged. For the past 24 years, she has worked at the University of Pennsylvania as a professor of neurosurgery. Prof. Karikó was noted for her exceptional persistence in working on mRNA, despite the academic establishment not seeing the potential of the field at the time. For her groundbreaking work, she has received numerous awards, including the Japan Prize, the Horwitz Prize, the Paul Ehrlich Prize, the Benjamin Franklin Medal, the Kovalenko Medal, the Tang Prize, the Warren Alpert Prize and the Lasker-DeBakey Clinical Medical Research Award.

Professor Katalin Karikó. Courtesy of István Sahin-Tóth

Professor Weissman is an immunologist focused on RNA biology. He received his MD and Ph.D. from Boston University. He opened his lab 1997 at the University of Pennsylvania, focusing on RNA and vaccines. Currently, he is developing methods to replace genetically deficient proteins, edit the genome, and specifically target cells and organs, all relying on RNA. He is the recipient of multiple awards, including the Rosenstiel Award, the Lasker-DeBakey Clinical Medical Research Award, and the VinFuture Prize. Together with Prof. Karikό, he is recognized for his pioneering work in developing nucleoside-modified mRNA, thereby successfully suppressing the inflammatory response to mRNA molecules and opening the door to RNA-based therapeutics.

Professor Drew Weissman. Photo credit: University of Pennsylvania School of Medicine

Professor Cullis, of the Department of Biochemistry and Molecular Biology at the University of British Columbia, has made fundamental advances in the development of nanomedicines employing lipid nanoparticle (LNP) technology for cancer therapies, gene therapies and vaccines. He developed unique lipid nanoparticles that protect and deliver mRNA into cells – the platform that was later adapted for RNA-based vaccines.

Professor Pieter R. Cullis. Photo credit: The University of British Columbia

Prof. Cullis received his Ph.D. in physics from the University of British Columbia, where he later established his own lab. He co-founded two Canadian National Centre of Excellence networks, the Centre for Drug Research and Development (now AdMare) and the NanoMedicines Innovation Network. He has received many awards, including the Order of Canada, the Prince Mahidol Award, the Canada Gairdner International Award, and the Tang Prize. In 2023, he was elected a Fellow of the Royal Society.

Science and Technology

Professor Quinn is a particle physicist and an educator. Together with the late Roberto Peccei, she introduced the Peccei–Quinn Symmetry, which explains the invariance of the strong interactions under the combination of parity and charge-conjugation. The particles predicted by this symmetry, known as axions, may furthermore constitute the dark matter, which makes up most of the matter in the Universe according to gravitational measurements. Prof. Quinn also showed, together with Howard Georgi and the late Steven Weinberg, that despite their different strengths at low energies, the strong, weak, and electromagnetic interactions may originate from a single force at high energies, leading to the theoretical framework known as grand unification. Her scientific discoveries broke new ground in theoretical physics, generated new research paths in both theoretical and experimental physics and may constitute a major advancement in understanding the basic structure of the universe.

Prof. Quinn received her Ph.D. from Stanford University. She was a professor of physics at SLAC and President of the American Physical Society. She is a member of the U.S. National Academy of Sciences. Her list of awards includes the Dirac Medal, the Oskar Klein Medal, the Karl Taylor Compton Medal, the Benjamin Franklin Medal, and the J. J. Sakurai Prize.

Professor Emerita Helen Quinn. Photo credit: Dan Quinn

The $75,000 Harvey Prize was established in 1971 by Leo Harvey (1887-1973), an industrialist and inventor, and an ardent friend and supporter of the Technion and the State of Israel. It is awarded by the Technion each year for outstanding achievements in science and technology, human health, and significant contributions to humankind. Over the years, the Harvey Prize has become a predictor of the Nobel Prize, with more than 30% of Harvey laureates ultimately receiving the Nobel. The most recent Harvey Laureates to receive the Nobel Prize were Professors Emmanuelle Charpentier, Jennifer Doudna, and Reinhard Genzel, in 2020.

The prizes will be awarded in June 2024 at a festive event as part of the Technion Board of Governors meeting during Technion’s Centennial Year.

Prof. Israel Cidon

NEW YORK (August 22, 2023) – Cornell Tech announced today that Prof. Israel Cidon – entrepreneur, renowned leader in network engineering and former faculty member and Dean at the Andrew and Erna Viterbi Faculty of Electrical and Computer Engineering at Technion–Israel Institute of Technology – joins Cornell Tech as director of the Joan & Irwin Jacobs Technion-Cornell institute. Cidon will succeed Ron Brachman whose appointment began in 2016.

The Jacobs Technion-Cornell Institute at Cornell Tech pushes the boundaries of academia at Cornell Tech, with dual-degree programs in Health Tech, Connective Media, and Urban Tech. Since its founding, the Jacobs Institute has incubated 42 new startup companies, which have filed almost 50 patent applications and secured more than $200 million in private funding. More than 80% of these companies are still operating and, in aggregate, they employ well over 200 employees in New York City.

As the new Director, Cidon will lead the Jacobs Institute’s strategic vision as it continues to grow its interdisciplinary, translational research focused on grand challenges in the digital realm; its innovative dual-degree programs; and its commitment to inclusive entrepreneurship.

“Professor Cidon has led groundbreaking research, co-founded several successful start-ups and developed 65 U.S. patents covering aspects of data networks including mobility, packet switching, security, Internet, and beyond,” said Cornell Tech Dean and Vice Provost Greg Morrisett. “His extensive expertise, start-up and industrial research experience – including at VMWare, one of Silicon Valley’s leading companies – will be fundamental to advancing the Jacobs Institute’s mission of offering a global perspective on research, education, technology transfer, commercialization and entrepreneurship.”

“Professor Israel Cidon is an esteemed computer networking researcher with extensive management experience at the Technion,” said Technion President Professor Uri Sivan. “As Dean he led the Andrew and Erna Viterbi Faculty of Electrical and Computer Engineering to significant achievements. Professor Cidon has a rich and successful background in entrepreneurship, and he maintains close relationships with the industry. I am confident that he will contribute significantly to strengthening the collaborations between Technion and Cornell University and advancing research and development at the Jacobs Technion-Cornell Institute.”

“The Jacobs Institute represents the academic partnership between Cornell University and the Technion–Israel Institute of Technology at Cornell Tech,” said Israel Cidon, Head of the Jacobs Technion-Cornell Institute. “It’s a privilege to succeed Ron Brachman as director of the Jacobs Institute and build upon Ron’s leadership, furthering the institute’s innovative approach to research and industry partnership.”

Cidon comes to the Institute from VMware Research, where for over six years he served as Vice President and Researcher working on high-performance, world-wide networks that bridged IoT, data centers, public clouds and more, enabling and optimizing geo-distributed modern applications. Prior to his time at VMware, he worked as a faculty member at The Technion–Israel Institute of Technology, published over 180 peer reviewed papers and served as Dean of Electrical and Computer Engineering from 2006 to 2010. Cidon has cofounded a number of technology companies, including Micronet Ltd., an early mobile data entry pioneer; Actona Technology, which introduced the basic technology for WAN optimization; Viola Networks, a network quality of service testing and diagnosis; and Sookasa, an organizational SaaS security platform.

About Cornell Tech

Cornell Tech is Cornell University’s groundbreaking campus for technology research and education on Roosevelt Island in New York City. Our faculty, students and industry partners work together in an ultra-collaborative environment, pushing inquiry further and developing meaningful technologies for a digital society. Founded in partnership with the Technion-Israel Institute of Technology and the City of New York, Cornell Tech achieves global reach and local impact, extending Cornell University’s long history of leading innovation in computer science and engineering.

About Technion – Israel Institute of Technology

The Technion – Israel Institute of Technology celebrates its first centennial this year. The impact of the Technion on Israel’s economy, society and defense is unmatched. It has long leveraged boundary-crossing collaborations to advance breakthrough research and technologies that impacted the world. Now, with a presence in three countries, the Technion prepares the next generation of global innovators. Technion people, ideas and inventions made immeasurable contributions to the world, innovating in fields from cancer research and sustainable energy to communication theory, quantum technologies, nanotechnology, and computer science.

Haifa, Israel – August 15, 2023 –The Technion was ranked in 79^th place on the list of the world’s top 100 universities according to the Shanghai Ranking, the foremost index in the world for ranking institutions of higher education.

The recently unveiled ranking places the Technion at the 79th position among the world’s top 100 universities, as per the Shanghai Ranking. This achievement marks a noteworthy ascent from its placement at 83rd position last year and the 94th position two years ago. Notably, the Technion has secured the 5th rank among European technological universities.

Prof. Uri Sivan, the President of the Technion, expressed that the Technion’s placement on the Shanghai Ranking underscores the institution’s robust standing among the global top 100 universities and its substantial advancement in recent years. Prof. Sivan emphasized that this international recognition underlines the Technion’s excellence in research, reaffirming its continuous success.

The President further stated, “The presence of three Israeli academic institutions within the world’s top 100 universities is a testament to the excellence of Israeli academia and science. This achievement fills us with pride.”

The Technion’s upward journey in recent years reflects its dedicated efforts in fostering interdisciplinary research collaborations, spearheading new research directions at the cutting edge of global research, and promoting research partnerships with industry. The institution’s accomplishments are the result of the tireless contributions of its faculty and staff members, administrators, department heads, and university deans.

2023 marks the centenary of the Technion’s establishment, a milestone that underscores the institution’s impressive accomplishments since its inception. “By addressing the grand challenges of the 21st century, the Technion will continue to pursue its historic role in driving the State of Israel and the world at large towards prosperity and well-being” says Sivan.

The Academic Ranking of World Universities (ARWU), responsible for publishing the Shanghai Ranking annually since 2003, evaluates universities based on the number of Nobel Laureates, Fields Medalists, Highly Cited Researchers, and publications in journals like Nature and Science. Universities with a substantial number of papers indexed by Science Citation Index-Expanded (SCIE) and Social Science Citation Index (SSCI) are also considered. In total, over 2500 universities are evaluated, and the top 1000 are published in the ranking.

The research group of Professor Yoav Shechtman from the Technion – Israel Institute of Technology Faculty of Biomedical Engineering has developed groundbreaking technology enabling scientists to see dynamic processes in living cells. Their study was recently published in Nature Methods.

Prof. Yoav Schectman

Until now, high-resolution microscopy enabled researchers to observe sub-cellular structures such as organelles, but at the cost of a long acquisition time – a minute or more per image – so whatever was being looked at needed to be held perfectly still.

This posed a real problem for biologists, since living cells, and the organelles inside them, are naturally in constant motion. One can fix them in place artificially, but then they are not in their natural state.

A study led by Ph.D. student Alon Saguy and Prof. Yoav Shechtman offers an innovative solution that uses artificial intelligence (AI) to enable scientists to see sub-cellular dynamics without being compromised by long acquisition times.

Ph.D. Student Alon Saguy

How does one find what they are looking for under a microscope? In biology, scientists commonly use fluorescent dyes to stain specific structures of interest. This creates high-contrast images of the labelled structures, which can then be seen clearly. There is, however, a physical limit on how good a resolution one can achieve using this methodology. It cannot resolve objects smaller than 200nm – approximately half the wavelength of visible light.

For some uses, a resolution of 200nm is good enough. But many structures in the cell are much smaller. Microtubules, which form the cell’s “skeleton,” for example, are only ~25nm thick. For the methodology to make such structures visible, Professors Eric Betzig, Stefan Hell, and William E. Moerner received the Nobel Prize in Chemistry in 2014.

The technique Betzig developed, called single-molecule localization microscopy (SMLM) relies on making not a single image, but a video recording of the fluorescently labelled sample. In each frame, only a few individual molecules emit light, creating a sparse speck pattern. Each speck of light is localized in high resolution and the localizations of the entire video are stacked together to form a high-resolution image.

SMLM has a significant drawback: since exposures of over a minute are required to generate a single high-resolution image, the cell must be fixed, like old photos, which required subjects to stand still for a long time, lest the image come out blurry.

And just as a photo – or even more so, a video – of a child in play or an athlete mid-jump is truer to life than the postured old photographs, scientists need to see the cell and the organelles within it move, respond to stimuli, and do the things that they naturally do.

The Technion team developed a clever solution. “Things move in a living cell, but they move with a certain regularity,” Prof. Shechtman explained. “If we look at microtubules, for example, they are sort of like threads, bound together into a mesh. They move, but you don’t have bits of them randomly hopping about. There’s a pattern to the movement.”

Artificial Neural Networks (ANNs) are powerful AI tools that are very good at finding patterns. Prof. Shechtman and his team trained their ANN to find patterns in SMLM videos. The ANN would receive the recording frame by frame, each frame showing only a few spots of light and produce a continuous video of the structures behind those spots. Using this methodology, the group was able to visualise multiple cell structures and their natural movement. They achieved a resolution of 30nm and temporal resolution of 15ms – an improvement of four orders of magnitude in the temporal resolution relative to the original SMLM method.

This new technology constitutes a major leap in biologists’ ability to study living cells, a tool that will enable them to make new discoveries.

The study was done in collaboration with Dr. Onit Alalouf and Nadav Opatovski from the Technion, and Prof. Mike Heilemann and Soohyen Jang from Goethe University, Frankfurt, and was generously supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation), the European Union’s Horizon 2020 research and innovation program, and the Zuckerman Foundation.

In the two large squares on the left, different biological structures can be seen that were scanned under a microscope. The squares on the right show the results of the scan as obtained by different methods, and it is clear that the highest resolution was achieved with DBlink technology – the rightmost square in each column

Video demonstration of the research

Click here for the paper Nature Methods

Click here for photos

For more information: Doron Shoham, Spokesperson

Researchers from the Technion have won the prestigious EIC Pathfinder grant from the European Union. The entire grant totals some 4 million Euros, of which 1.5 million Euros will be allocated to research done at the Technion.

Prof. Eitan Yaakobi

The research is led by Professor Eitan Yaakobi and Professor Zohar Yakhini, who are the research coordinators of the project. Both are members of the Henry and Marilyn Taub Faculty of Computer Science. Profs. Yaakobi and Yakhini are both experts in DNA data storage, a field that is considered one of the most promising directions in the world of information, since a single gram of DNA may serve to store enormous amounts of information when properly encoded. Considering the dizzying increase in the volume of information in the world, there is a constantly increasing need for a cheap, compact, and non-polluting alternative.

Prof. Zohar Yakhini

Server farms (the “cloud”) not only consume about 3% of global electricity today, but also “contribute” about 2% overall carbon emissions to the atmosphere. The DNA alternative, on the other hand, provides significant miniaturization (six to ten orders of magnitude), retention of the information for a much longer time and negligible energy cost.

The basic idea is as follows: in an artificial process (synthesis), DNA molecules are produced that contain information in different sequences of the four letters of the language of heredity – the nucleotides, marked with the letters, G, C, A, and T.

To read the information, sequencing of the DNA is required, a relatively simple process whose cost decreases year by year. The research of Profs. Yakhini and Yaakobi addresses the synthesis process itself, which is the main challenge in the field. The grant is intended to support the two researchers and their partners in the development of advanced methods for the synthesis of artificial DNA that will be faster, cheaper, and more accurate. In addition, the research will also address issues such as privacy and information security and applications in the field of cryptography.

The other researchers on the project are Antonia Wachter-Zeh and Prof. Reinhard Heckel from TUM, Prof. Mark Somoza from the LSB Institute at TUM, Prof. Robert Grass from ETH Zurich, and Prof. Kunal Masania from TU Delft.

The EIC Pathfinder grants support researchers who develop new and ground-breaking technologies that carry significant impact potential, as well significant risk (High Risk, High Gain). Last year, Technion researchers Prof. Boaz Pokroy and Prof. Ester Segal won the grant for the development of technology that will protect agricultural crops.

For a video on the subject click here.

Congratulations to the Israeli Chemistry Olympic team, which came back from the IChO (International Chemistry) Olympiad in Zurich, Switzerland with four medals! 356 students from 90 countries took part in the competition. The Israeli team was trained at the Technion – Israel Institute of Technology by Prof. Zeev Gross from the Schulich Faculty of Chemistry.

The medallist students are: Neta David Eiger from Emek HaMaayanot – silver medal; Shoham Assis from Karmiel – silver medal; Yonatan Gontmaher from Rishon LeTsiyon, silver medal; Shon Hentz from Gan Yavne – bronze medal.

Prof. Zeev Gross, Schulich Faculty of Chemistry, team supervisor: “The experience of an international Olympiad, with the participation of students from 90 countries, was amazing. Our students, assisted by the dedicated training personnel, succeeded in proving their skills, the four medals they won are a testimony to that. We are very proud of them!”

Yoav Kisch, Minister of Education: “I congratulate our students on their impressive achievements. They make us proud and give us hope. These students are Israel’s next generation, investment in them is investment in the future of Israel.”

Yarom Ariav, CEO Maimonides Fund: “Congratulations to Israel’s science teams, who demonstrated impressive accomplishments in the international Olympiads. The team members give us an opportunity for national pride and optimism in all that concerns the outstanding skills of Israeli youth.”

Eli Fried, Director General of the Maimonides Fund: “A great thank you, and our deepest esteem to the Israeli teams for the pride and inspiration they give us all. The Maimonides Fund will continue to provide advanced training and high-quality tools, in collaboration with the Ministry of Education and the academic institutions, to help the next generation become trailblazers in all walks of life.”

Researchers at the Technion – Israel Institute of Technology have developed a coherent and controllable spin-optical laser based on a single atomic layer. This discovery is enabled by coherent spin-dependent interactions between a single atomic layer and a laterally confined photonic spin lattice, the latter of which supports high-Q spin-valley states through the photonic Rashba-type spin splitting of a bound state in the continuum.

Published in the prestigious journal Nature Materials and featured in the journal’s Research Briefing, the achievement paves the way to study coherent spin-dependent phenomena in both classical and quantum regimes, opening new horizons in fundamental research and optoelectronic devices exploiting both electron and photon spins.

The study was conducted in the research group of Professor Erez Hasman, head of the Atomic-Scale Photonics Laboratory, in collaboration with Professor Elad Koren, head of the Laboratory for Nanoscale Electronic Materials and Devices in the Department of Materials Science and Engineering, and Professor Ariel Ismach at Tel Aviv University. The two groups at the Technion are in association with the Helen Diller Quantum Center and Russel Berrie Nanotechnology Institute. Dr. Kexiu Rong conducted and led the research, and collaborated with Dr. Xiaoyang Duan, Dr. Bo Wang, Dr. Vladimir Kleiner, Dr. Assael Cohen, Dr. Pranab K. Mohapatra, Dr. Avinash Patsha, Dr. Subhrajit Mukherjee, Dror Reichenberg, Chieh-li Liu, and Vladi Gorovoy.

Prof. Erez Hasman

Can we lift the spin degeneracy of light sources in the absence of magnetic fields at room temperature? According to Dr. Rong, “Spin-optical light sources combine photonic modes and electronic transitions and therefore provide a way to study the exchange of spin information between electrons and photons and to develop advanced optoelectronic devices. To construct these sources, a prerequisite is to lift the spin degeneracy between the two opposite spin states either in their photonic or electronic parts.

This is usually accomplished by applying magnetic fields under a Faraday or Zeeman effect, although these approaches generally require strong magnetic fields and cannot produce miniaturized sources. Another promising way takes advantage of artificial magnetic fields for photonic spin-split states in momentum space, underpinned by a geometric phase mechanism.

Unfortunately, previous observations of spin-split states have relied heavily on propagation modes with low quality factors, which impose undesired limitations on spatial and temporal coherence of the sources. This approach is also hindered by the spin-controllable properties of a bulk laser gain material being unavailable or nontrivial to access for active control of the sources, especially in the absence of magnetic fields at room temperature.”

To achieve high-Q spin-split states, the researchers constructed photonic spin lattices with different symmetry properties, which comprise an inversion-asymmetry core and inversion-symmetry cladding integrated with a WS₂ monolayer to create laterally confined spin-valley states. The essential inversion-asymmetry lattice the researchers use has two important properties. (1) A controllable spin-dependent reciprocal lattice vector due to space-variant geometric phases from its constituting inhomogeneous-anisotropic nanoholes.

This vector splits a spin-degenerate band into two spin-polarized branches in momentum space, being referred to as the photonic Rashba effect. (2) A pair of high-Q symmetry-enabled (quasi-) bound states in the continuum, that is, ±K (corners of the Brillouin zone) photonic spin-valley states, at the band edges of the spin-split branches. Moreover, the two states form a coherent superposition state with equal amplitudes.

Professor Koren noted that, “We used a WS₂ monolayer as the gain material because this direct-bandgap transition metal dichalcogenide possesses unique valley pseudospins, which have been widely investigated as an alternative information carrier in valleytronics. Specifically, their ±K’ valley excitons (radiated as in-plane spin-polarized dipole emitters) can be selectively excited by spin-polarized light according to a valley-contrasted selection rule, thus enabling active control of spin-optical light sources without magnetic fields.”

Some of the researchers involved in the research in the laboratory of Prof. Erez Hasman

In the monolayer-integrated spin-valley microcavities, ±K’ valley excitons couple to ±K spin-valley states owing to polarization matching, and spin-optical excitonic lasing is achieved at room temperatures through strong optical feedback. Meanwhile, ±K’ valley excitons (initially without a phase correlation) are driven by the lasing mechanism to find the minimum-loss state of the system, which leads them to re-establish a phase-locked correlation according to the opposite geometric phases of ±K spin-valley states.

This lasing-mechanism-driven valley coherence removes the need for cryogenic temperatures to suppress the intervalley scattering. Moreover, the minimum-loss state of the Rashba monolayer laser can be regulated to be satisfied (broken) via a linear (circular) pump polarization, which provides a way to control the lasing intensity and spatial coherence.

“The unveiled photonic spin valley Rashba effect provides a general mechanism to construct surface-emitting spin-optical light sources. The demonstrated valley coherence in the monolayer-integrated spin–valley microcavity makes a step towards achieving entanglement between ±K’ valley excitons for quantum information by means of qubits,” explains Professor Hasman.

“For a long time, our group has been working on developing spin optics to harness photonic spin as an effective tool to control the behavior of electromagnetic waves. In 2018, we were attracted by valley pseudospins in two-dimensional materials, and therefore began a long-term project to study the active control of atomic-scale spin-optical light sources in the absence of magnetic fields.

We initially tackled the challenge of coherent geometric phase pickup from individual valley excitons by using a non-local Berry-phase defect mode.

However, the underlying coherent addition of multiple valley excitons of the realized Rashba monolayer light sources remained unsolved, owing to the lack of a strong synchronizing mechanism between the excitons.

This issue inspired us to think about high-Q photonic Rashba modes. Following innovations in new physical approaches, we achieved the Rashba monolayer laser described here.”

Artist illustration of a spin-valley Rashba monolayer laser. The spin-valley optical microcavity is constructed by interfacing an inversion-asymmetric (yellow core region) and an inversion-symmetric (cyan cladding region) photonic spin lattice. By virtue of a photonic Rashba-type spin splitting of a bound state in the continuum, this heterostructure enables a selective lateral confinement of the emergent photonic spin-valley states inside the core for high-Q resonances. Consequently, the coherent and controllable spin-polarized lasing (red and blue beams) is achieved from valley excitons in an incorporated WS2 monolayer (purple region). (Credit: Scholardesigner co, LTD)

The research was supported by the Israel Science Foundation (ISF), the Helen Diller foundation and the joint Technion NEVET grant by RBNI. The fabrication was performed at the Micro-Nano Fabrication & Printing Unit (MNF&PU) of the Technion. Laboratory sites: https://hasman.technion.ac.il/, https://koren.net.technion.ac.il/.

The paper ‘Spin-valley Rashba monolayer laser‘, Nature Materials, DOI number: 10.1038/s41563-023-01603-3, https://www.nature.com/articles/s41563-023-01603-3