UCLA engineers shrink powerful terahertz systems onto a single semiconductor chip

Approach could advance ultrafast wireless communication, imaging and remote sensing

University of California - Los Angeles

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Professor Mona Jarrahi (left) working with her doctoral student Yifan Zhao (right) on the terahertz photonic chip.

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Credit: Terahertz Electronics Lab/UCLA

High-frequency waves classified as terahertz occupy a relatively underused region of the electromagnetic spectrum between infrared light and microwaves. Researchers have long recognized its unique potential for applications including ultrafast wireless communication, security screening, remote sensing and medical imaging.

As technologies push toward higher operating frequencies and data rates, photonics-based terahertz systems, which use light at superspeed to generate and process terahertz signals, have emerged as a promising alternative to conventional electronic technologies because of their superior bandwidth and power efficiency. However, today’s terahertz optoelectronic systems, which are electronic systems that control light, remain bulky, complex and difficult to scale for widespread use. They typically rely on multiple separate components — including lasers, amplifiers, modulators, sources and detectors — that must be individually made, aligned and interconnected, limiting use outside specialized laboratory settings. 

Now, a UCLA-led research team has demonstrated a way to integrate these functions onto a single semiconductor chip compatible with modern photonic technologies. The breakthrough, published in Nature Communications, paves the way for compact, scalable terahertz systems for next-generation communication, imaging and sensing applications.

By adapting terahertz generation and detection to be compatible with photonic integrated circuits, the researchers from the UCLA Samueli School of Engineering demonstrate a path toward shrinking laboratory-scale terahertz systems into compact, mass-producible chips — much like electronic integrated circuits transformed computers from refrigerator-sized machines into modern microprocessors.

“Terahertz optoelectronic systems have been bulky, expensive, power-hungry and difficult to scale for widespread use,” said study leader Mona Jarrahi, a professor of electrical and computer engineering and holder of UCLA Samueli’s Northrop Grumman Chair in Electrical Engineering. “By demonstrating that many of these functions can be integrated onto a single chip using proven industry-standard fabrication platforms, our study opens the door to practical, scalable terahertz technologies for real-world applications.”

Earlier approaches to single-chip optoelectronic terahertz systems primarily relied on specialized materials and fabrication techniques incompatible with standard photonic chip technology.

The team’s breakthrough focused instead on quantum well semiconductor structures — extremely thin layers of material engineered to control light — tailored to simultaneously generate, detect, modulate and amplify terahertz signals on a single shared chip platform.

Quantum wells are already widely used in photonic integrated circuits. The researchers’ key innovation was demonstrating that these structures could also support terahertz signal generation and detection through a process called gain-enhanced interband photomixing, in which two laser beams combine to generate signals at a desired wavelength.

Using quantum well substrates in photonic integrated circuits, the team demonstrated highly efficient terahertz generation and highly sensitive terahertz detection relative to existing photomixer-based, or light interference-based, terahertz technologies. 

At UCLA, Jarrahi is also a member of the California NanoSystems Institute and faculty director of the Semiconductor Hub at UCLA Samueli, a $125 million, industry-backed initiative that aims to accelerate research and workforce development in AI-powered chip technologies.

Other authors on the paper include UCLA electrical and computer engineering doctoral students Yifan Zhao, Shahid-E-Zumrat and Szu-An Tsao — all members of Jarrahi’s research group, the Terahertz Electronics Lab. The study was funded by the U.S. Office of Naval Research, the U.S. Department of Energy and the Institution of Engineering and Technology Harvey Prize.

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DOI

10.1038/s41467-026-73080-6 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Terahertz generation and detection through gain-enhanced interband photomixing in quantum well structures

A chip-scale terahertz source leveraging gain-enhanced interband photomixing for high-efficiency terahertz signal generation.

Credit

Terahertz Electronics Lab/UCLA

 

A superconductor's hidden identity revealed

The Hebrew University of Jerusalem

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Shahar Simon 

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Credit: Avigail Ben Eliyahu

New study reveals that two widely studied ultrathin superconducting materials are more sophisticated than they appear. Although they seem to behave like simple superconductors with a single energy gap, they actually contain two strongly interacting superconducting states that work together and disguise themselves as one. This finding resolves a long-standing mystery about how these materials behave, providing new insight into superconductivity that could help scientists design better superconducting materials for future technologies such as quantum computers, ultra-efficient electronics, and advanced sensors.

Sometimes, the biggest scientific discoveries come from looking more closely at something we thought we already understood.

For decades, physicists have studied a remarkable class of materials called superconductors—materials that can carry electricity with zero energy loss. These materials could one day help power ultra-efficient electronics, quantum computers, and advanced medical technologies.

One of the most widely studied superconductors, niobium diselenide (NbSe₂), seemed straightforward when peeled down to just a few atomic layers. Experiments suggested it behaved like a superconductor with a single energy gap—a fundamental fingerprint that describes how electrons order in pairs, to flow without resistance.

But researchers suspected there was more to the story. The study, led by PhD. student Shahar Simon and MSc. student Maya Klang under the guidance of Prof. Oded Millo, and Prof. Hadar Steinberg of the Racah Institute of Physics and the Center for Nanoscience and Nanotechnology at the Hebrew University of Jerusalem, was published in Physical Review Letters.

Using extremely sensitive tunneling spectroscopy measurements, the team found that the material wasn't behaving like a simple, single-order superconductor at all. Instead, it was hiding two different superconducting orders that interact so strongly they appear as one. The same hidden behavior was also found in another closely related material, TaS₂.

"It's a bit like listening to what sounds like a single singer, only to discover it's actually a perfectly synchronized duet," said the researchers.

The discovery solves a long-standing puzzle. Previous experiments could not fully explain the detailed shape of the superconducting energy spectrum using traditional theories. By applying a more sophisticated model, accounting for the presence of two different superconduting orders, the Hebrew University team was able to accurately explain not only the measurements themselves, but also how the materials respond when exposed to magnetic fields.

The findings also suggest that the thicker, bulk version of NbSe₂ may actually contain three interacting superconducting orders, revealing an even richer picture of how superconductivity works in these materials.

Understanding this hidden complexity could help scientists design and engineer future superconducting devices with greater precision. As researchers work toward technologies such as quantum computers and ultra-efficient electronic devices, knowing exactly how electrons behave inside these materials becomes increasingly important.

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Journal

Physical Review Letters

DOI

10.1103/p836-tdgw 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Two-Band Superconductivity in Few-Layer NbSe₂ and TaS₂

 

Quantum materials discovery could advance electronics for extreme environments

University of Arizona researchers demonstrate a potential new use for graphene nanoribbons that could improve semiconductor technologies for fusion energy and space systems

University of Arizona

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University of Arizona Provost Postdoctoral Fellow Ali Habiboglu uses a molecular beam epitaxy system to synthesize graphene nanoribbons – a material Zafer Mutlu and collaborators are investigating for use in next-generation radiation-sensing devices and electronics.

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Credit: Photo by Leslie Hawthorne Klingler, University of Arizona Office of Research and Partnerships

TUCSON, Ariz. — University of Arizona researchers have demonstrated a promising new application for graphene nanoribbons, a nanoscale semiconductor material with the potential to withstand extreme environments. The team's findings could help clear a key hurdle to bringing fusion energy to the electric grid.

For the proof-of-concept study, published in the journal ACS Applied Materials & Interfaces, the researchers integrated the nanoribbons, known as GNRs, into semiconductor devices and exposed them to gamma radiation. Their results suggest that the ribbons could serve as radiation sensors for fusion reactors and in deep space, where intense radiation challenges existing technologies and close monitoring of material degradation could help keep critical systems operating reliably.

"The devices survive the exposure and still respond, but their electrical performance changes dramatically," said principal investigator Zafer Mutlu, University of Arizona assistant professor of materials science and engineering in the College of Engineering. "That's exactly the behavior we want from a sensor."

GNR-based sensors could help unlock fusion energy as a clean, near-limitless power source by improving how engineers monitor the condition of a reactor's first wall. This innermost barrier separates the superheated fuel from the reactor structure and gradually degrades under intense radiation, requiring periodic inspection and replacement. Engineers track that damage, but today's silicon-based sensors cannot survive inside the first wall. Instead, they must be placed outside the barrier, forcing reliance on indirect measurements during operation and physical inspection after shutdown.

Because the gamma exposure left the ribbons' atomic framework intact while producing a strong, measurable electrical response, the researchers suggest GNR-based sensors could eventually be engineered to operate closer to the reactor core than today's electronics can survive – potentially reducing costly shutdowns for inspection and maintenance and increasing the amount of time fusion power plants can remain in operation.

"Real-time monitoring is our vision for this project," Mutlu said.

Inside the discovery

While this is the first study of GNRs' response to gamma radiation, they're widely studied as leading candidates for pushing chip technology beyond the limits of silicon. Their microscopic size and durability could improve the speed and energy efficiency of chips used in everything from artificial intelligence systems to smartphones.

Mutlu and eight additional study authors, all from the U of A, synthesized the ribbons from the molecular level before embedding them in common semiconductor devices. They used emerging fabrication techniques Mutlu helped develop to make the ribbons exactly nine atoms wide and one atom thick and about 45 nanometers long on average – tens of thousands of times thinner than a human hair.

The minuscule ribbons behave according to the rules of quantum physics rather than classical physics, Mutlu said. In the absence of radiation, current flows in a well-defined way through GNRs, like the ones used in the study. The researchers' measurements indicate that gamma radiation passing through the surrounding air produces reactive molecules that subtly alter the ribbon edges without changing their overall structure. At this scale, quantum effects amplify the impact of small changes on electrical signal transport through the material.

The researchers propose that the changes trigger a quantum effect called Anderson localization, which traps charge-carrying electrons in place and sharply reduces current, producing the signal of radiation exposure that could provide more precise data for reactor maintenance planning.

Long considered a promising source of large-scale, carbon-free electricity, fusion has

reached key laboratory milestones, including experiments since 2022 that have produced more energy than the lasers delivered to the fuel they consumed, but still faces major engineering barriers. U of A researchers are collaborating with industry on efforts to scale enabling technologies and deliver fusion power to the grid. 

Similar to this fusion application, GNR sensors could provide state-of-health data for space systems – including communications satellites, Earth-observation satellites, and deep-space probes – and identify early signs of radiation-related wear before failures occur.

Pushing materials design at the nanoscale

The next step for Mutlu and his collaborators is to test the same device under different radiation doses. They also plan to explore GNRs of different sizes. After those investigations, Mutlu is confident the synthesis method used in the study will allow researchers to customize new forms of ribbons.

"You can design the material atom by atom, molecule by molecule. You can make it less sensitive, more sensitive, non-sensitive," said Mutlu, whose research has focused on quantum materials and semiconductor devices for more than a decade.

That level of control is important for future space systems, where both electronic components and monitoring devices must operate for long periods under continuous radiation exposure. The same ability to tailor the material at the atomic level could support radiation-resistant semiconductor chips as well as sensors that track system performance over time.

The paper's co-first authors were postdoctoral researcher Kentaro Yumigeta and doctoral student Muhammed Yusufoglu. University Distinguished Professor Jon T. Njardarson's group in the Department of Chemistry and Biochemistry, in the College of Science, synthesized the molecular building blocks for the ribbons. Mutlu's group carried out the nanoribbon synthesis, device fabrication and electrical characterization, and the gamma irradiation experiments were led by materials science and engineering professor Barrett G. Potter and University Distinguished Outreach Professor Kelly Simmons-Potter of electrical and computer engineering.

This research was supported by funding from the Semiconductor Research Corporation and the National Science Foundation.

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DOI

10.1021/acsami.6c02516 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Electrical and Structural Response of Nine-Atom-Wide Armchair Graphene Nanoribbon Transistors to Gamma IrradiationArticle link copied!

 

Depoliticization weakens AIDS activism in Brazil

After decades of playing a leading role in health policy, the social movement against the disease is fragmenting and losing momentum

Fundação de Amparo à Pesquisa do Estado de São Paulo

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Brazil’s HIV/AIDS response program is considered a success story. As early as 1987, Brazil became the first developing country to guarantee free treatment. The country is also known for its social activism, which helped build the Unified Health System (SUS) and shape public policies based on scientific evidence and human rights. 

Important milestones in the fight against AIDS emerged through the alliance between civil society, public health professionals, and the government, such as universal and free access to antiretroviral drugs and the domestic production of diagnostic tests. One notable decision was the patent waiver for the antiretroviral drug efavirenz in 2007.

However, after decades of success, this leading role has lost momentum. The field of activism, once guided by a certain political consensus, has become fragmented. This is due to the changing profile of people living with HIV (“pauperization” of the epidemic) and the reorientation of health policies, which has also led to a shift in civil society’s priorities. Consequently, anti-AIDS activism in Brazil has become depoliticized. Helena Achcar of the Center for Public Sector Policy and Economics at the Getulio Vargas Foundation (CEPESP-FGV) reached this conclusion in an article published in the journal Sociology of Health & Illness.
 
“The movement’s decline can’t be explained by a lack of funding alone, but above all by the changing profile of activists and the priorities imposed by the pauperization of the epidemic. Also contributing to this trend are technological advances and the growing medicalization of the response to HIV, which favor quick, biomedical solutions at the expense of public health and the fight against inequalities,” Achcar told Agência FAPESP.

“It’s important to emphasize that the idea that AIDS has been resolved is misleading, and therefore activism remains one of the pillars of the Brazilian response,” the researcher adds.

The study, supported by FAPESP, is based on the theory of practice (or field theory) developed by the French sociologist Pierre Bourdieu. 

Achcar examined the demobilization of the AIDS movement in Brazil through four main, interrelated concepts: the social space of struggle and competition among different actors (which Bourdieu calls the field); the actions internalized by movement members (habitus); the economic, social, cultural, and symbolic resources in contention (capital); and the dominant, naturalized discourse governing what is considered legitimate within the field (doxa).

“By analyzing the movement as a social field in which NGOs, networks, and the state compete for power and legitimacy to define legitimate activism, I sought to capture the field’s symbolic and internal dynamics and its interaction with changes in external environments,” she says.

A bit of history

Achcar explains that in the 1980s, leaders such as the sociologist Betinho and the writer and former guerrilla fighter Herbert Daniel (among others) developed a radical, intellectualized, deeply political form of activism. They framed AIDS as an issue of democracy and social justice. This movement originated in the middle class and formed strategic alliances with the public health movement.

However, starting in the 1990s, HIV began to spread among more vulnerable populations with lower levels of education and income. New participants joined the movement with urgent demands for food, housing, and access to basic services. These demands shifted priorities and fragmented the political culture that had been built in previous decades. 

“The thesis I advocate, inspired by Bourdieu, is that we all develop a kind of mental framework over the course of our lives [what Bourdieu calls ‘habitus’]. This habitus shapes our actions and the way we see the world. It isn’t individual but shared by social groups. When the AIDS epidemic began to affect people with a habitus associated with more disadvantaged classes, the political debate within the movement shifted as well, and basic issues such as access to food, housing, and income became central,” Achcar explains. 

Starting in the 2010s, the medicalization of AIDS policies gained momentum. “The ‘end of AIDS’ narrative reduced the disease to a biomedical issue and masked the structural inequalities that many policies and the movement sought to address,” states the researcher.

The study points out that the response to HIV was progressively absorbed by a neoliberal logic that prioritizes rapid biomedical solutions, technical management, and measurable results. “Historically politicized NGOs were pressured to professionalize in order to raise funds, becoming service providers and losing part of their activist capital,” she says.

Another significant change in the external landscape occurred in the late 2000s when Brazil ceased to be a priority for international donors, and when domestic budget cuts reduced opportunities for social participation. “The promise of an end to AIDS through a supposed magic formula reinforced the idea that the epidemic would be resolved solely through medication, downplaying debates about structural inequalities,” the researcher continues. 

Activists interviewed by Achcar describe the current movement as weak and unable to fight as it once did. “Tensions between long-standing NGOs and new identity-based networks have deepened the fragmentation. The former universalist identity that mobilized activism as a whole has given way to disputes over legitimacy and scarce resources,” she says.

She concludes, “This study shows that the future of Brazil’s response to HIV depends on the ability to rebuild alliances, restore the movement’s political character, and address the inequalities that continue to fuel the epidemic.”

About São Paulo Research Foundation (FAPESP)
The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe

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Journal

Sociology of Health & Illness

DOI

10.1111/1467-9566.70187 

Article Title

A Bourdieusian Approach to the Demobilisation of Brazil's AIDS Movement

 

And you thought a smart ring was discreet

Thread-based electronics that conform to the body could point toward softer, less obtrusive health monitors

Tufts University

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Flexible organic eutectogel transistors arranged in a complete thread-based circuit. The free-form circuits can easily conform to body contours to monitor health and movement

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Credit: Wenxin Zeng

Imagine using a wearable device that is so thin and discreet that you’d hardly be aware that you were wearing it. Now Tufts engineers have created flexible electronics that could do just that. Made of thread-based integrated circuits that can bend, coil, stretch, and conform to the body’s contours and movements, the devices are designed to exist in free form, sewn into clothing or wrapped around curved and moveable surfaces.

These kinds of devices worn on the body or adhered to the skin could potentially track a wide range of biomarkers or environmental conditions, while AI-driven applications could synthesize the resulting data into useful insights for fitness, healthcare, and recovery from injury or disease.

To accomplish this, Sameer Sonkusale, Jon A. Levy School of Engineering Professor, and his colleagues, including Matt Panzer, E Ink Professor of Engineering, created each of the components of complex integrated circuits—from transistors to sensors—in the form of threads. The devices are described in the journal Applied Materials and Interfaces.

Wearable devices like smartwatches and smart rings are popular—more than a third of U.S. adults use them—and many offer health tracking. Thread-based integrated circuits could help make wearable health monitors more comfortable and discreet, incorporated into clothing, soft interfaces, or skin-contacting threads that move naturally with the body. 

Other health-related applications could be sutures to track wound healing or monitoring for movement indicators of cognitive decline, fall risk for the elderly, and breathing in infants.

“By moving electronics from planar patches to free-form threads, we have opened a path toward wearable bioelectronics that are more like fibers than hardware,” said Sonkusale. “They will be soft, stretchable and able to follow the body’s shape rather than forcing the body to accommodate the device. They could even potentially be used like sutures to monitor processes inside the body.”

The researchers demonstrated circuits capable of amplifying signals from sensitive sensors, and as a proof-of-concept for wearable monitoring, they created a device that can be placed on the temple to detect blinking, and another device near the diaphragm to detect changes in breathing patterns and rates. These demonstrations suggest that the technology could one day support soft wearable systems for monitoring health, stress, and other conditions.

“The technology platform is still in early stages,” said Wenxin Zeng, Ph.D. candidate in electrical engineering at Tufts and lead author of the study, “but we expect to improve the speed and precision of fabrication, and the ability of the thread-based integrated circuits to carry out more complex functions.”

Transformative Materials  

Running throughout the device circuit are thin threads coated with gold. Tiny and entirely flexible transistors—the basis of any digital device—are attached to the thread, which includes a conducting plastic-like material that bridges the gold thread leading into and out of the transistor. The flow of electrons at the transistor can be turned on and off like a spigot, depending on a second current that controls a “gate,” which acts like a valve. 

An important innovation making the thread devices possible is something called a eutectogel. The gel can help create a gap, less than a millimeter, between two ends of the electronic thread where the flow of electrons can be controlled, whether in a thread-based resistor, capacitor, sensor or other component. Others have used hydrogels to connect the wires, which can dry up. In contrast, the eutectogel is stable, soft, and compatible with being in contact on or in the body. 

The eutectogel also gives the transistor a “self-repair” capability. If the gel breaks, the researchers showed that bringing the pieces back together and applying gentle heat can restore its mechanical and electrical function. The thread itself is not repairable if cut, but the gel components can be rejoined.

Unlike traditional integrated circuits that require photolithography—depositing patterned layers of material on a surface—or high temperature processing, no clean room is needed in their fabrication, making the approach more compatible with soft polymers and textile-like materials and making possible development with low-cost manufacturing.

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DOI

10.1021/acsami.5c25103 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Free-Form Three-Dimensional Integrated Circuits on a Thread Using Organic Eutectogel-Gated Electrochemical Transistors