An international research team, led by scientists from the EMPA (Zurich) and the International Iberian Nanotechnology Laboratory, which has researchers from the UPV/EHU, has succeeded in building chains of quantum magnets made of nanographene that capture the essence of one of the core models of quantum magnetism. The team’s results (Nature, “Observation of fractional edge excitations in nanographene spin chains”) have implications for understanding quantum magnetism on the nanoscale and may open the door to building quantum computers. | |
We are all used to the idea that simple units combine to form more complex structures. So atoms combine to form molecules, which in turn combine to form cells, and cells form tissue, ultimately giving rise to living beings. | |
In the quantum world, this process may take place in reverse in such a way that the interaction between complex particles results in simpler particles. So, under certain circumstances, the interaction between electrons, indivisible particles with electric charge e, gives rise to the emergence of particles with charge e/3. This phenomenon is known as fractionalization. | |
Quantum magic: fractionalizing spins |
|
All elementary particles have intrinsic properties such as mass or charge that are intuitive to us, and others such as spin, which can be visualised like a compass. However, unlike normal compasses, which can point in any direction, the spin of quantum systems is quantized, and can only assume a discrete set of values. For example, we say that the spin of an electron is ½ and can only take two values. Particles with spin 1 can take three values. | |
In the 1980s the British physicist Duncan Haldane built a mathematical model for spin 1 particles in which the fractionalization of the spins took place. So when a one-dimensional chain of indivisible spin 1 particles interacted with their neighbours, they gave rise to the emergence of spin ½ particles on the edges of the chain. | |
Like the magic trick in which the magician saws a person in half and pulls the two halves apart, the Haldane model allows spins 1 to be fractionalized and separated. It is one of the core models of quantum magnetism, and his work earned him the Nobel Prize in 2016. | |
One-dimensional chains of magnetic molecules assembled from graphene |
|
Experimental confirmation of this prediction was challenging for various reasons, chief among them being the fact that one-dimensional materials do not exist. Indirect evidence of the phenomenon of spin fractionalization in organometallic materials containing chains of magnetic atoms existed, but direct observation remained elusive. | |
Now, however, that observation has been made by an international team of researchers, including the Ikerbasque researcher David Jacob of the Department of Polymers and Advanced Materials: Physics, Chemistry and Technology at the UPV/EHU; he has collaborated in this work with the INL, the University of Alicante, the EMPA in Zurich and the University of Dresden. | |
To accomplish this difficult feat, the researchers combined organic chemistry techniques with ultra-high vacuum surface science in order to synthesise graphene molecules with spin 1 that form unidimensional chains. Using a tunnelling microscope, the team of researchers were able to study, with atomic resolution, the quantum states of the chain adsorbed on a gold surface, compare them with those predicted by the theory, and establish that the system did in fact behave like the Haldane model. | |
In particular, in chains with a sufficiently high number of magnetic molecules, the researchers found Kondo resonances at the tips of the chain, a phenomenon that occurs when spin ½ particles interact with the electrons in a conductor such as gold. From one-dimensional chains to two-dimensional networks and quantum computers | |
The researchers say that this work “shows the potential for using nanographenes to form two-dimensional networks of nanomagnets, enabling predictions analogous to Haldane’s to be confirmed, such as, for example, the existence of quantum states that would allow quantum computation to be carried out”. |
News
X Marks the Spot: AI’s Treasure Maps Lead to Early Disease Detection
Medical diagnostics expert, doctor’s assistant, and cartographer are all fair titles for an artificial intelligence model developed by researchers at the Beckman Institute for Advanced Science and Technology. Their new model accurately identifies tumors [...]
Scientists Discover Method To Identify Alzheimer’s Disease Before It Progresses to Dementia
Researchers at Aarhus University have discovered a method to identify Alzheimer’s disease before it progresses to dementia, potentially opening up new avenues for treatment. A groundbreaking study could pave the way for early detection [...]
Startling Discovery: COVID-19 Virus Can Stay in the Body More Than a Year After Infection
The COVID-19 virus can persist in the blood and tissue of patients for more than a year after the acute phase of the illness has ended, according to new research from UC San Francisco that offers potential [...]
New bioengineered protein design shows promise in fighting COVID-19
In the wake of the COVID-19 pandemic, scientists have been racing to develop effective treatments and preventatives against the virus. A recent scientific breakthrough has emerged from the work of researchers aiming to combat [...]
Sugar-coated gold nanoparticles can quickly eliminate bacterial infections, no antibiotics required
If left to their own devices, bacteria on our teeth or wounded skin can encase themselves in a slimy scaffolding, turning into what is called biofilm. These bacteria wreak havoc on our tissue and, [...]
Liquid Lightning: Nanotechnology Unlocks New Energy
EPFL researchers have discovered that nanoscale devices harnessing the hydroelectric effect can harvest electricity from the evaporation of fluids with higher ion concentrations than purified water, revealing a vast untapped energy potential. Evaporation is a natural [...]
Unmasking the Illusion: AI-Generated Faces Challenge Perceptions
Research shows survey participants duped by AI-generated images nearly 40 percent of the time. If you recently had trouble figuring out if an image of a person is real or generated through artificial intelligence [...]
New Discovery Reveals How Cells Defend Themselves During Stressful Situations
Stress granules play a crucial role in the stress response, arising from the aggregation of non-translating mRNAs and proteins. Although significant knowledge exists about stress granules, the mechanisms behind their mRNA localization remain partially [...]
Scientists use a new type of nanoparticle that can both deliver vaccines and act as an adjuvant
Many vaccines, including vaccines for hepatitis B and whooping cough, consist of fragments of viral or bacterial proteins. These vaccines often include other molecules called adjuvants, which help to boost the immune system's response [...]
Not Science Fiction: How Optical Neural Networks Are Revolutionizing AI
A novel architecture for optical neural networks utilizes wavefront shaping to precisely manipulate the travel of ultrashort pulses through multimode fibers, enabling nonlinear optical computation. Present-day artificial intelligence systems rely on billions of adjustable [...]
Turning skin cells into limb cells sets the stage for regenerative therapy
In a collaborative study, researchers from Kyushu University and Harvard Medical School have identified proteins that can turn or “reprogram” fibroblasts — the most commonly found cells in skin and connective tissue — into [...]
AI reveals prostate cancer is not just one disease
Artificial Intelligence has helped scientists reveal a new form of aggressive prostate cancer, which could revolutionise how the disease is diagnosed and treated in the future. A Cancer Research UK-funded study, published in Cell Genomics, has revealed [...]
New Study Finds That Persistent COVID-19 Infections Are Surprisingly Common
Recent research conducted by the University of Oxford has found that a high proportion of SARS-CoV-2 infections in the general population lead to persistent infections lasting a month or more. The findings have been published in the journal Nature. [...]
Innovative nanosheet method revolutionizes brain imaging for multi-scale and long-term studies
The human brain has billions of neurons. Working together, they enable higher-order brain functions such as cognition and complex behaviors. To study these higher-order brain functions, it is important to understand how neural activity [...]
Scientists Have Discovered a Potential Universal Antivenom
Scientists at Scripps Research identified antibodies that protect against a host of lethal snake venoms. Scripps Research scientists have developed an antibody that can block the effects of lethal toxins in the venoms of [...]
Scientists discover the human brain is even more powerful than we thought
The human brain could be far more powerful than we ever imagined, scientists have discovered. Researchers have identified cell messaging which have never been uncovered before, which suggests our brains are capable of more than previously realised. It’s [...]