Magnetizing quantum communication

Strengthening the brightness of single-photon light sources with magnetism

Kyoto University

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Magnetic field enhanced single-photon emission from defects in two-dimensional semiconductors

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Credit: Kyoto U / Matsuda lab

Kyoto, Japan -- As the demand for more secure data transmission increases, conventional communication technologies are facing limitations imposed by classical physics, and are therefore approaching their limits in terms of security. Fortunately, quantum communication may help us overcome these restrictions.

Quantum communication harnesses the quantum nature of light by utilizing single photons as information carriers. This is a fundamentally different approach from conventional communication technologies and has the potential to lead to the development of secure, high-performance communication systems.

These future quantum technologies will require new single-photon emission sources. Recently, extremely thin two-dimensional semiconductors with a thickness of only a few atomic layers have shown great potential due to their excellent electrical and optical properties. Although increasing the efficiency of such single-photon generation is extremely important, the capacity of these materials and its strategy had not been thoroughly explored.

This inspired a team of researchers at Kyoto University to investigate what they predicted may be a functional single-photon emission source. They hypothesized that a semiconductor in single-layer tungsten diselenide, in which they introduced a single defect, would bind excitons -- electron-hole pairs -- to the defect and emit only a single photon.

To realize this idea, the team prepared a sample of monolayer tungsten diselenide, heating it to introduce a small number of defects and to artificially break the crystal symmetry, which resulted in two distinct luminescence peaks representing bright excitons and dark excitons.

The researchers then measured the luminescence and photon correlation at a temperature of about -265°C, applying an external magnetic field to control the emission, revealing that the emission intensity significantly increased even when they applied a relatively weak magnetic field.

Using photon correlation measurements, the team also observed that emitted light demonstrated photon antibunching, indicating that photons are emitted one by one. This suggests that, even under a magnetic field, it can function as a single-photon source, and that the magnetic field can enhance the efficiency of single-photon generation.

"This is significant because it shows that single-photon emissions can be generated and manipulated with an external magnetic field in a two-dimensional semiconductor, revealing it to be a promising platform for the development of secure, efficient, and compact quantum information devices," says team leader Kazunari Matsuda.

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The paper "Magnetic brightening and its dynamics of defect-localized exciton emission in monolayer two-dimensional semiconductor" appeared on 4 June 2025 in Science Advances, with doi: 10.1126/sciadv.adr5562

About Kyoto University

Kyoto University is one of Japan and Asia's premier research institutions, founded in 1897 and responsible for producing numerous Nobel laureates and winners of other prestigious international prizes. A broad curriculum across the arts and sciences at undergraduate and graduate levels complements several research centers, facilities, and offices around Japan and the world. For more information, please see: http://www.kyoto-u.ac.jp/en

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Journal

Science Advances

DOI

10.1126/sciadv.adr5562 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Magnetic brightening and its dynamics of defect-localized exciton emission in monolayer two-dimensional semiconductor

 

Cultural values shape tourists’ view of eco-friendly B&Bs

University of South Australia

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The demand for ‘greener’ bed and breakfast (B&B) accommodation is gaining traction worldwide, but operators should heed cultural differences when marketing their sustainable facilities, according to a new international study.

Led by Hong Kong Shue Yan University and the University of South Australia, the survey of 800 people from 37 countries examined how cultural values, age and education levels influenced tourists’ acceptance of environmentally sustainable features in B&Bs.

Previous global studies have indicated that many tourists are willing to pay more for environmentally friendly accommodation, but this is the first time that researchers have focused specifically on cultural attitudes towards B&B sustainable practices.

The study focused on five categories of sustainable facilities: water treatment systems (rainwater harvesting systems, greywater); greenery systems (sky gardens and vertical green walls); sanitation (hand sanitiser and air purification units); ventilation (natural air or air conditioning); and eco-friendly facilities (LED lights, organic composting bins).

Tourists from rules-based, autocratic and hierarchical countries such as China, India and Malaysia expressed the strongest support for all types of green features in B&Bs. Deemed ‘high-power distance’ cultures, citizens of these countries were more likely to use energy-saving products and choose natural ventilation over air conditioning, the survey revealed.

University of South Australia (UniSA) researchers Dr Li Meng and Professor Simon Beecham, who co-authored the study published in Consumer Behaviour in Tourism and Hospitality, say other cultural dimensions were less clear cut.

“Western cultures such as Australia, the United Kingdom and United States, appreciated rooftop gardens and vertical green walls, but these features were not strong factors in whether they chose a bed and breakfast,” according to the UniSA researchers.

Tourists from risk-averse cultures such as Japan, France and Greece were less likely to embrace B&Bs with natural ventilation, preferring to control their environment with air conditioning, the researchers say.

Highly-educated travellers rated sanitation and eco-friendly features more favourably, and younger tourists placed greater value on green systems than older people.

“These findings challenge assumptions that all green tourists are alike,” says lead author Professor Rita Yi Man Li from Hong Kong Shue Yan University.

“Many accommodation providers want to operate more sustainably, but few have considered how cultural values affect guest preferences,” Prof Li says.

“This research shows that guests from different cultural backgrounds respond differently to the same green features. Understanding these nuances can help B&B owners tailor their sustainability investments more effectively depending on their most important tourism markets.”

Dr Meng says younger guests may be drawn to visible features like rooftop gardens, while more educated visitors may look for practical elements like composting, LED lighting, or air purification systems.

The researchers say that governments also have a role to play in supporting the development of sustainable B&Bs.

By offering incentives, investing in sustainable infrastructure, and developing policies such as easing travel restrictions and visa policies, governments can help expand the international customer base for eco-friendly B&Bs, the study recommended.

‘Does culture really matter? A cross-cultural study of demand for B&B sustainable facilities’ is published in Consumer Behaviour in Tourism and Hospitality. DOI: 10.1108/CBTH-04-2024-0135. The study involved a cross-disciplinary team of researchers with expertise in economics, real estate, literature and environmental science.

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Journal

Consumer Behavior in Tourism and Hospitality

DOI

10.1108/CBTH-04-2024-0135 

Method of Research

Survey

Subject of Research

People

Article Title

Does culture really matter? A cross-cultural study of demand for B&B sustainable facilities

Article Publication Date

27-Jul-2025

 

New research reveals diverse survival strategies of reef-building corals in response to ocean acidification

Research

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Figure 1. 3D reconstructions of polyp–canal systems visualized the corrosion process in reef-building corals under acidic stress.

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Credit: Copyright © 2025 Yixin Li et al.

As global climate change intensifies, ocean acidification is becoming a ‘relentless killer’ threatening coral reef ecosystems. Recently, a research paper published in the international authoritative journal Research has revealed diverse survival strategies of reef-building corals in response to ocean acidification, providing a new perspective for understanding and protecting this fragile marine ecosystem.

Survival crisis under ocean acidification

Since the Industrial Revolution of the Anthropocene, human activities have led to a continuous decline in global ocean pH levels. According to predictions, by the end of this century, the global average seawater pH may drop from 8.0-8.2 to 7.6-7.8, posing a lethal survival crisis for marine organisms that rely on calcium carbonate skeleton systems, especially reef-building corals. While existing research has confirmed that ocean acidification reduces skeletal density and growth rates of reef-building corals, there have been no reports on the survival strategies of different coral species in response to acidified marine environments, particularly the precise dynamic changes of their internal skeleton and canal structures.

To explore these issues in depth, the research team simulated an acidified marine environment with pH values of 7.6-7.8 in the laboratory. They selected four species of reef-building corals widely distributed in the Indo-Pacific region: Acropora muricata, Pocillopora damicornis, Montipora capricornis, and Montipora foliosa. Using high-resolution micro-computed tomography (micro-CT), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and transcriptome sequencing (RNA-seq) detection technologies, the researchers conducted multidimensional integrated analysis of the skeletal erosion process, elemental dynamic changes, and gene expression states of these reef-building corals under acidified marine environments (Figures 1, 2).

Species-specific survival strategies: unique ‘cavity-like’ and universal ‘osteoporosis’

The results suggest that different reef-building coral species have diverse growing strategies in lower pH conditions. A. muricata demonstrated its unique ‘cavity-like’ acid erosion strategy, while the other three species developed degradation characteristics similar to ‘osteoporosis’ in human aging processes, exhibiting disordered skeletal structures, insufficient synthesis of adhesion proteins, and low bone mass, correspondingly.

1) A. muricata: ‘cavity-like’ strategy of sacrificing internal structure to preserve the colony

The acidification damage in A. muricata does not start from the surface of skeleton, but firstly occurred inside the coral skeletons. During the erosion process, there were no obvious cracks on the surface of skeleton and the polyp-canal system regulating coral growth was minimally affected. Since the polyp-canal system is the basis for the sustainable growth of reef-building corals, this survival strategy of sacrificing internal structures inside the skeletons to protect the basic canal network, helps A. muricata maintain its growth patterns. Gene analysis revealed that this coral specifically up-regulates the expression of adhesion proteins (such as galaxin and collagen alpha-6 chain-like) under acidification stress, potentially to maintain skeletal toughness despite internal dissolution, thereby enhancing the protective capacity of the coral colony like ‘super glue’ (Figures 2, 3). This strategy of prioritizing protection of vital centers demonstrates the unique adaptive potential of A. muricata.

2) Other three reef-building corals: ‘osteoporosis’ like symptoms

In contrast, Pocillopora damicornis, Montipora capricornis, and M. foliosa exhibited characteristics similar to ‘osteoporosis’, where erosion begins from skeletal surfaces, leading to overall structural degradation. In M. capricornis, insufficient synthesis of adhesion proteins responsible for cementing calcium carbonate crystals makes its skeleton more ‘brittle’. M. foliosa shows overall bone mass loss, leading to decreased skeletal quality and hardness. The skeletal micro-structure of P. damicornis (especially in corallite regions) becomes disordered, with newly formed skeletons even irregularly squeezing the living space of coral polyps, damaging mechanical strength and long-term survival ability.

Mechanistic insights: polyps create ‘life barriers’ in acidified oceans

The study also discovered an important mechanism: ocean acidification primarily damages pre-existing ‘old’ skeletons of reef-building corals, while having relatively limited inhibitory effects on ongoing ‘new’ calcification near polyps. In all studied reef-building corals, polyps form natural protective shields within approximately 1 millimeter of their surroundings. Skeletons farther from polyps dissolve earlier, while skeletal regions near living polyps are damaged later and to a lesser extent, with new skeletal deposition even occurring in areas adjacent to polyps. This indicates that polyps can regulate their micro-environment to preferentially protect skeletal regions directly attached to them, overturning traditional understanding that acidification directly inhibits calcification.

Research significance: providing new scientific basis for coral reef protection

This study systematically reveals the unique response strategies of different reef-building coral species to ocean acidification. Particularly, the unique ‘cavity-like’ strategy of A. muricata provides new insights for understanding the stress resistance of reef-building corals. The ‘osteoporosis-like’ symptoms exhibited by other reef-building corals suggest that ocean acidification weakens coral reef structural stability at different levels. By identifying vulnerable points and potential recovery mechanisms of different reef-building corals, more targeted protection strategies can be developed. This interdisciplinary in-depth research provides a new theoretical foundation for protecting the ‘tropical rainforests’ of our blue oceans.

This research was completed through collaboration between research groups led by Zuhong Lu and Chunpeng He at Southeast University, Yuehuan Zhang and Yanping Qin at Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), and emerging scientist Yixin Li at Dalian University of Technology.

Sources: https://doi.org/10.34133/research.0736

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Journal

Research

DOI

10.34133/research.0736 

Method of Research

News article

Subject of Research

Not applicable

Article Title

Skeleton-Forming Responses of Reef-Building Corals under Ocean Acidification

 

‘Bone-ified muscles’ could be robots’ next flex

Bioinspired artificial muscles enable robotic limbs to push, lift and kick

Northwestern University

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A composite image of the robotic leg — with integrated artificial muscles — bending at the ankle and knee.

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Credit: Ryan Truby/Taekyoung Kim/Northwestern University

Future robots could soon have a lot more muscle power.

Northwestern University engineers have developed a soft artificial muscle, paving the way for untethered animal- and human-scale robots. The new muscles, or actuators, provide the performance and mechanical properties required for building robotic musculoskeletal systems.

To demonstrate the artificial muscle’s capabilities, the engineers implemented them into a life-size humanoid leg, complete with rigid plastic “bones,” elastic “tendons” and even a sensor that enables the robot to “feel” its movements. The leg used three artificial muscles — a quadricep, hamstring and calf — to bend its knee and ankle joints. The muscles are compliant enough to absorb impacts but still can apply enough strength and motion to kick a volleyball off a pedestal.

The new bioinspired materials innovation could change how robots walk, run, interact with humans and navigate the world around them.

The study was published on July 24 in the journal Advanced Materials.

“Robots are typically constructed from rigid materials and mechanisms that enable precise motion for specific tasks,” said Northwestern’s Ryan Truby, the study’s senior author. “But the real world is constantly changing and incredibly complex. Our goal is to build bioinspired robotic bodies that can be flexible, adaptable and embrace the uncertainty of the physical world. This includes bringing together not only practical artificial muscles, but also bone- and tendon- or ligament-like components to robotics. If we can do that, then robots won’t just become more resilient and adaptable. They will be able to harness the mechanics of softer materials to become more efficient.”

Truby is the June and Donald Brewer Junior Professor of Materials Science and Engineering and Mechanical Engineering at the McCormick School of Engineering, where he directs The Robotic Matter Lab. Taekyoung Kim, a postdoctoral scholar in Truby’s lab, is the study’s first author.

Current challenges in replicating muscle

Stiff, rigid and clunky, most current robots have difficulty smoothly adapting to uneven terrain or performingcomplex, delicate tasks without breaking other objects or injuring themselves. 

“It’s difficult to make robots without physical compliance smoothly respond or adapt to external changes and safely interact with humans,” Kim said. “To make future robots move more naturally and safely in unstructured environments, we need to design them more like human bodies — with both hard skeletons and soft, muscle-like actuators.”

More recently, roboticists have started developing soft actuators with muscle-like mechanical properties. But current approaches often need large, heavy equipment to power or drive them. And, even then, they are not durable enough and cannot generate enough force to complete real tasks.

“It’s really difficult to engineer soft materials to perform like muscle,” Truby said. “Even if you can make a material move like an artificial muscle, there are many other challenges like transmitting sufficient force with enough power. Interfacing them with rigid bone-like features presents even more problems.”

Making the artificial muscle

To overcome these challenges, the team looked to an actuator previously developed in Truby’s lab. At the heart of the actuator is a 3D-printed cylindrical structure called a “handed shearing auxetic” (HSA). The HSA has a complex structure that enables unique movements and properties, such as extending and expanding when twisted. The twisting motion needed to move the HSA can be generated by a small, integrated electric motor. Kim developed a method of 3D-printing HSAs from a common, inexpensive rubber often used in cellphone cases.

In their new design, the team encased the HSA in a rubber origami bellows structure that enables the rotating motor to drive the assembled actuators’ extension and contraction. The actuators now push and pull with impressive strength, performing as artificial muscles. The muscle can even dynamically stiffen when actuated — just like a human muscle.

Each muscle weighs about as much as a soccer ball and is slightly larger than a can of soda. It can stretch up to 30% of its length, shrink and lift objects 17 times heavier than itself. Perhaps most crucial to their use in robotic bodies, the muscle can be battery powered, bypassing the need for heavy, external equipment.

A human-scale leg that can ‘kick’ and ‘feel’

To demonstrate the muscle’s real-world potential, Truby, Kim and their team used 3D printing to build a human-sized robotic leg. The team constructed the leg’s “bones” from rigid plastic and tendon-inspired connectors from rubber. The elastic tendons connect the quadricep and hamstring muscles to the shank bone and the calf muscle to the foot structure. The tendons and muscles helped dampen movements and absorb shocks, similar to a biological musculoskeletal system.

The team also added a flexible, 3D-printed sensor that allows the leg to “feel” its own muscle. Designed like a sandwich, a conductive layer of flexible plastic is squished between two non-conductive layers. When the artificial muscle moves, the sensor does too. As it stretches, its electrical resistance changes, allowing the robot to sense how much its muscle extends or contracts.

The resulting leg is compact and battery powered. A single charge from a portable battery supplied enough energy to allow the leg to bend its knee thousands of times in an hour. Achieving similar capabilities with other soft actuator technologies would be difficult if not impractical. 

“By engineering new materials for robotics with the performance and properties of biological musculoskeletal systems, we can build robots to be more resilient and robust for real-world use,” Truby said. “We’re excited to see how these artificial muscles can drive new directions for humanoid and animal-like robots.”

Other authors on the study are Eliot Dunn, a high school student research intern in the Robotic Matter Lab, and Melinda Chen, a participant in the Research Experience for Undergraduates (REU) program run by the Northwestern University Materials Research Science and Engineering Center (NU MRSEC). The work was supported by the Office of Naval Research (grant number N00014-22-1-2447) and Leslie and Mac McQuown through Northwestern’s Center for Engineering Sustainability and Resilience.

This composite image shows how the soft actuator can bend and flex.

Credit

Ryan Truby/Taekyoung Kim/Northwestern University

Robotic leg demo [VIDEO] 

Robotic leg flexes its 'muscle' [VIDEO] 

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Journal

Advanced Materials

DOI

10.1002/adma.202501290 

Article Title

Architected Soft Actuators for Artificial Musculoskeletal Systems

Article Publication Date

28-Jul-2025

 

Tropical fishes on the move survive better with temperate neighbours

University of Adelaide

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As tropical fishes colonise new habitats in temperate oceans, those who shoal alongside neighbours that are native to the area learn behaviours that help them thrive.

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Credit: Courtesy of the University of Adelaide.

As tropical fishes colonise new habitats in temperate oceans, made available to them because of ocean warming, researchers have found that those who shoal alongside neighbours that are native to the area learn behaviours that help them thrive.

According to the study, performed jointly by researchers from the University of Adelaide and the University of Technology Sydney, tropical fish species that live in mixed shoals, not solely among other tropical fishes, became bolder and fed more, which may aid them in surviving longer and growing larger on temperate reefs.

“This result suggests that novel species interactions, which are often assumed to be stressful or competitive, can benefit some range-extending species,” says lead author Dr Angus Mitchell, from the University of Adelaide’s School of Biological Sciences.

“Shoaling with locals may help tropical fish learn about new predators, food sources, and environmental cues. This reduces uncertainty and boosts survival in unfamiliar ecosystems.”

This work builds upon previous University of Adelaide research that found tropical fish experience decreased physiological performance in temperate ecosystems.

“Our new work demonstrates that novel shoaling interactions could buffer against maladaptive physiological responses,” says co-author Dr Chloe Hayes, from the University’s School of Biological Sciences.

The new study, published in the Journal of Animal Ecology, found that while tropical fishes may thrive in these new environments, the temperate fishes whose habitat is being encroached upon do not enjoy a similar benefit.

“In the subtropics, we saw that temperate fish species, including the Australian Mado, suffered. They were more likely to flee and fed less when tropical species were present,” says co-author Professor David Booth, from the University of Technology Sydney.

These interactions may force temperate fish species out of their warmest native areas permanently.

“Subtropical reefs already sit at the thermal limits for many temperate fish. Added stress from tropical competitors could tip them over the edge,” says project leader Professor Ivan Nagelkerken, from the University of Adelaide.

Knowledge of the interspecies dynamics that occur due to climate change-induced migration will be important when designing conservation strategies.

“Our research shows that climate-driven species redistributions are not just about temperature. They are also about the new relationships formed in recipient ecosystems,” says Professor Nagelkerken.

“As the world’s oceans continue to heat up, understanding the outcomes of these novel interactions, whether friend or foe, will be critical for predicting how reef communities will be reshaped in a rapidly warming ocean.”

The University of Adelaide and the University of South Australia are joining forces to become Australia’s new major university – Adelaide University. Building on the strengths, legacies and resources of two leading universities, Adelaide University will deliver globally relevant research at scale, innovative, industry-informed teaching and an outstanding student experience. Adelaide University will open its doors in January 2026. Find out more on the Adelaide University website.

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DOI

10.1111/1365-2656.70100